Sunday 16 October 2011

What to do with one of those huge lenses

What to do with one of those huge lenses? I don't mean the modern very long telephoto lenses designed for your DSLR that probably cost £thousands. I mean those interesting and very impressive pieces of glass that were designed for specialist antique cameras that are not seen any more, and look so good and so tempting that you might just buy one at a fair or car-boot or on the *bay. After all, they are very large and were once very expensive, and that must mean they are very good, right?

The lenses I am thinking of are often 4-6 inches across, a similar length, weigh 1-2 kilos, and either came from an old process camera (which means they were used once for copying maps or making prints or posters or adverts or suchlike), or came from a aeroplane (where they were used for aerial reconnaissance), or possibly came from a very large projector, or epidiascope (a bit like an overhead projector) or something similar. All these are industries of yesteryear, so the lenses are being sold off on second-hand markets, and and currently available and often inexpensive.

Actually, lots of people (myself included) seem to be tempted into spending money on large lenses, though if you are tempted have a good think beforehand, what it is worth and what you will do with it. It is not so easy to think of uses for these old lenses.

Applications and problems

The main problems with these lenses are their size, focal length, and design. They may have been designed for huge cameras, or for copying at 1:1, which may limit their use to normal pictorial photography. But the main thing is they are heavy, typically with long focal length, and are not telephoto in design which makes them more difficult to operate on a small camera.

Telephoto lenses are lenses that have been specially designed to be small and compact for their focal length. A telephoto 500mm lens is less than 500mm in length. This is good as you don't want half a metre of lens in front of your camera. But a non-telephoto of focal length 500mm will have to have its centre 500mm away from the film or CCD in your camera. And that may be a long way to hold a very heavy lens. The mount will have to be very strong to hold the lens at one end and the camera at the other without sagging.

So unless your building skills are very good, these heavy long lenses are likely to be difficult to mount on your DSLR. I will show you an idea on how to mount such a lens soon, but first here are some other ideas.

Build a very large camera. These big lenses are big not so much because their focal length is long but because they make a very big image. It makes sense to use them this way. But building and using ultra large format (ULF) cameras is a bit of a specialists art, and not for the faint of heart.

Modify the lens. Inserting a "reducing" element between the lens and film (usually a positive achromatic lens) is a good idea. It makes the lens behave like a shorter focal length lens, and that size is used less for coverage but more for brightness of image. In other words you can get a super-fast lens this way. Unfortunately reducers reduce image quality, and you can only go so far this way. But it is worth trying.

Mount the lens anyway on your DSLR, perhaps for some specialist use only where the size and weight and complexity is less of a problem. This is what I will do here.

Telescopes from old camera lenses

I had a large 450mm f/4.5 lens from a wartime epidiascope and decided to try to mount it for my DSLR for astronomical use. This made sense as the size of the lens equates to light-gathering power, highly desirable in astronomy. I am not a serious amateur astronomer, I just wanted to make a telescope myself quickly and cheaply from parts I happened to have available. If you want to make yourself a really good telescope, this is unlikely to be the best way to go about it, but it is fun.

The main problem is how to hold a kilo of glass and aluminium rigidly half a metre from the camera. I decided to make a mount from lots of plywood and glue. (I have limited time, so like to put together my projects quickly. Modern glues are very strong, and plywood is light, strong and I had some available.)

So I measured and cut out my plywood. Making the holes to accept the lens was the hardest part.

4 inch telescope project (1)

It is important not just to know the focal length of your lens, but where this should be measured from. In fact the back focal length is a more useful parameter for construction - this is the distance between the back of the lens and the image when focussed at infinity. The best way to measure this is project a sharp image of the sun onto something. The focal length is useful to know too - this is essentially the magnification of the image at infinity, and will normally be written on the lens. It's a bit harder to measure unless you have some other lens to compare against.

After some more work, and quite a lot of glue, my lens was starting to take shape.

4 inch telescope project (2)

Now comes the hardest bit - making sure everything is in the correct position. This has to be accurate to a fraction of a millimetre, and even worse the lens must be central and square on, not at an angle. As you can see, my construction is not this accurate, and few DIYers' will be. The important thing is to devise something that will allow you to set up the mount accurately and that what all those screws on mine are for. They are for collimation - putting the lens and camera in a straight line. I did worry too much about the lens being exactly central (this is not so critical it turns out) but the screws enable the angle of the lens to be altered and for fine focus to be set up.

4 inch telescope project (3)

It is important that collimation is done by adjusting three screws only. (The reason is the same as why a three legged stool never rocks, but four-legged chairs often do unless you put a beer mat under one leg.) But I was worried that my three adjustable screws couldn't carry the large weight, so I added three more - not for adjustment but to secure everything when it is all set up. In fact the weight is not so much of a problem as I will set the lens on the tripod, so the screws only have to hold the weight of my DSLR (a rather light model), but even so I wanted to be safe.

That was a week-end's work. I have also mounted the lens on a tripod, and checked that I can focus the lens by roughly focusing against something on the horizon. (For these large lenses, this focus might be a millimetre or two different from the focus point for an astronomical object.) All the gluing is setting and I need to tidy up and try it out sometime soon. More in this blog soon.

Friday 9 September 2011

An easy swirly mod with extras

Yesterday I blogged about some of my attempts to get the Petzval swirl effect using home-made lenses in all formats from 4/3, 135 (35mm) to larger formats. The swirl effect is certainly possible with care in all formats, though generally speaking works better on larger formats. The lens-build is a bit involved, and needs some fiddling with sizes to get it right. It occurred to me when writing it that there might be an easier mod that anyone can do to get a lens to swirl on a DSLR or 35mm SLR. So I tried it, and it works. And, to my surprise there a pleasant "extra" waiting for anyone that has a go.

I've not seen this mod anywhere else, so if you mention it to anyone do say you found it here.

Modifying a standard lens

For this mod you need a camera (a 35mm SLR or a DSLR) that takes old fashioned 35mm SLR lenses. Most DSLRs have adapters to do this, or you can use a 35mm SLR. As far as I can see any sensible focal length should work, though some may be more useful than others. I used a 50mm lens on an Olympus 4/3 DSLR. This would be good for portaits and close-up details. It is quite important that the lens has some "depth" i.e. is reasonably long and complicated. A simple meniscus lens may not work.

The idea is, just as in the previous blog to add apertures at the front and rear. They don't have to be the same size, but they do have to be circular and central. I cut out some stiff black paper and glued it on the rear. The hole is about 5mm in diameter. Warning: you don't want paper fouling up your mirror, film or CCD sensor! Make sure the rear one is very firmly in place and it doesn't foul the focusing mechanism of the lens. You'll have to cut it very carefully.

50mm M42 standard lens with new aperture at rear

The one on the front was a good fit so it stays on by itself without any glue. This hole is about 16mm in diameter.

50mm M42 standard lens with new aperture at front

To cut paper, I use a Stanley knife. Then I sand it down with emery paper. Sorry, these are old-fashioned English terms for the tools in question, but I don't know the words in other languages.

The sizes (diameters of the holes) are quite critical and depend on your lens, in particular how long it is, its focal length, and what format you are shooting. I was shooting 4/3 with an image size about 1/2 that of a 35mm negative. For 35mm or "full frame" you might double my sizes. If you get vignetting your holes are too small. If you don't get vignetting they are too large. You want it so that you only just don't get vignetting, or you only get a little. That's for both holes.

Testing it

That's it! Now for the testing. As I said before, this "new" lens will behave just like a normal one most of the time, except that the aperture control won't have much effect except when it is very small. You need the right conditions, in particular to open up wide, focus close and have interesting background. When I tried it it worked straight away.

Evening sun in the woods

Don't look at the flare for a moment - look at the corners, and see how they swirl?

But the flare is a feature of this mod and I wasn't expecting it, but like it a lot. (I don't mean the orange and purple patch - that is due to the glass I was using and I'd seen that before. I mean the obvious white flary thing.) I have seen flares like this before - on roughly cut home-made pinhole cameras. The rough edge of the paper is making the flare. I don't fully understand how it works, and especially don't understand why colours appear. It's something to do with the rough edges behaving like a diffraction grating. But does it matter? Go out and enjoy it!


For the purists, this isn't the true Petzval swirl. These lenses are too good. For the real thing you need to add astigmatism or aberrations. I am not sure how to do that in the context of this "easy" mod. If you have any ideas do let me know.

Thursday 8 September 2011

The Petzval swirlies

A certain kind of lens (called "Petzval Lenses") are very much in vogue because of the swirly effects they produce. You'll have to make up your mind what you think, but when used tastefully and subtly I rather like the effect .

Here's a Flickr gallery I made of some images with the Petzval swirl, and a few that claimed to have swirl but which are definitely not the real thing:

Does your camera swirl?

Obviously the first thing is to try it and see. You may be surprised. I was when I took a Tokina wide angle lens out a few months ago. This was a lens I had had for years and years, quite liked, but thought I knew it very well, what it could and couldn't do. But I just took some close-up shots of blossom and didn't think anything of it until I had scanned the negatives. I didn't see anything special in the (TTL) viewfinder when I took the shot, but to my astonishment when I looked at the scans, I got lots of swirl:


You need to know what sort of conditions to try, to get the swirlies. When your eye is "in" it gets a bit easier, but to start with make it easy for yourself. You need to focus on something close - so twist the focus right out and get in close to something interesting. You need to have lots of interesting background all out of focus. And you want that background to have lots of tiny points of bright light. Go into the woods on a sunny day, take someone to photograph, or photograph the leaves and branches but always keep an eye on the background for the light coming in between the leaves. To make the background really out of focus open the lens right out to its fastest aperture.

Home-made swirly lenses

So maybe your lens doesn't swirl. You may have noticed that the best swirlies come from very big large format cameras with these old Petzval lenses. (This is, I think true.) What do you do? Buy such a camera and lens?

Well maybe. But it will cost you a lot, and not just money: these cameras are expensive and complicated to use, and the really good swirly lenses are pricey too, and you must have the right lens for the right camera. (With a swirly lens on a camera that's too small you just don't see the swirl.) All this means there's a lot to learn.

Lot of people say Petzval swirl is impossible on small cameras such as 35mm SLRs and DSLRs. I beg to differ. I have done it. But it is harder.

Why does it swirl?

The popular opinion is that a lens fault called astigmatism causes swirls. This may be true. Petzval lenses do have astigmatism. In fact it is certainly true, to some extent: astigmatism does make a lens swirl under certain conditions, but it is not the only reason, and possibly not the main reason.

My theory is that, in most cases, the lens swirls because it has the shape of a long barrel and the swirls are caused by the circular aperture at one end mismatching the circular aperture at the other end. Petzval lenses always had a slot for an aperture in the middle to avoid this problem. (And it's only the crazy people that want the swirls that leave this out.) Other effects like spherical aberration and astigmatism then might help more and make the swirls more pronnounced or change them slightly.

This means to make a lens that swirls you need to make it in a long barrel. Also make the barrel just the right length and the diameter just right too.

The geometry of a long barrel can be simulated by a long tube with two apertures at each end. I made apertures by cutting black card into circles and cutting holes in them. (Be careful: they have to be exactly circular and central.) Otherwise the lens is just like the one I talked about before on this blog. You just need two (roughly equal) close-up filters at the ends of the tube, with an aperture on each.

Here are some examples.

Olympus E-420 with homemade  Petzval-style lens Praktica MTL5B with homemade  Petzval-style lens Home-made Petzval-style lens

They all work. But it is not easy to get these lenses right. As I said, the holes at each end have to be just the right size. Too small and you only see a circular image, too big and you miss the swirls. The focal length of the glass and the length of the tube is important too. Keep experimenting and you'll get there.

This was done with a home-made lens on a 35mm SLR. I got my 4/3 DSLR to swirl too.


Thursday 25 August 2011

Focal-plane shutters and camera-phone slit scan

The principle of slitscans explained and done deliberately in the last post also applies to "ordinary cameras" under certain circumstances. In the "old days" of film photography, this meant focal plane shutters.

Focal plane shutters

Most 35mm film SLR cameras have focal plane shutters. A few compact 35mm cameras have them too (usually the ones like Leicas or Zorkis with interchangeable lenses.) Some medium format cameras have focal plane shutters, and a small number of large format cameras have them. Focal plane shutters have two moving blinds next to the film - one blind opens and the other closes. The advantage for the camera manufacturers is that the closing blind can start to close before the opening blind has finished opening. This makes the shutter look like a slit moving across the film. The slit is narrower the "faster" the shutter is. That's why the manufacturers like these shutters: they don't have to make anything actually move fast, just make the slit narrower. Of course moving slits play havoc with other aspects of photography: they are not good if you want to take pictures with flash, but they are cheaper.

The famous picture by Lartigue is an old one taken with a rather slow focal plane shutter set so the slit is rather narrow. In this picture he captures the car quite sharp (but not the wheels) but it is "slanted" as the shutter or slit is moving from top to bottom. In fact to make it more complicated, Lartigue also pans the camera in the picture, but not enough to capture the car vertically.

If you own a camera with a focal plane shutter you might experiment with it: set it to its fastest speed and take photographs of rapidliy moving objects. Helicopter blades or aeroplane propellers are good subjects. Try holding the camera the nomal way, on its side, or even upside down. Some focal plane shutters (the majority, probably) go from side to side, and some go up and down. For example my Olympus OM1 has a side-to-side movement, whereas my Praktica MTL has an up-and-down movement. (Because of the vertical shutter Prakticas of the 1970s are ideal for these experiments.) I must try this again, but unfortunately I haven't got any nice images from these cameras to show here right now.

Digital slitscans

But in the modern age, some digital cameras work as slitscans too. In this case there is no slit moving but the camera's processor is so slow and is programmed to grab the scene a line at at time, that this moving line as it is "grabbed" is similar to a slit. Try the camera attached to your phone. Or even better get a very old phone and try that. My phone is quite old, and I was pleased to get this image out of the window of a moving car.

Lance charge

With some panning you might get a nice artistic illusion of speed.

Moving bus

Try to work out which way your phone or digital camera scans. I find my images are much better if I hold my phone upside down!

Sunday 21 August 2011

Slit scans on 35mm film

A while ago I wrote about multiple exposures and particularly about multiple exposure while winding film and panning or moving the camera. I promised I would explain the principle of the slitscan and how this evolves from the multiple exposure device. You may want to read the previous post at before going any further with this one.

To start with, take a camera which can take very long narrow images. The way I do this is I glue cardboard or metal directly onto the focal plane, just in front of the film, to stop light getting to any part of the film except the thin slit in question. A picture of a modified camera was on the previous post where it was pointed out that simple inexpensive point-and-click 120 film cameras are ideal.

With some practice, pointing the camera and winding on the film at coordinated rates, such a camera can produce pictures that are rather representational, because the panning and the winding on are both about the same amount.


A slitscan camera

If it wasn't for those nasty hard lines and rather clunky appearance this is almost a normal picture taken in a different way. Well how do we get rid on the lines? The idea is to arrange that the "slit" gets narrower and narrower until it is only a few pixels or so wide and the film is wound on smoothly past the slit by some mechanism. This is actually not too difficult to arrange. Here is a normal 35mm camera with a slit added

Petri TTL with focal plane slit 1

The process is likened to a flatbed computer scanner: this can only "see" a thin line at a time but with the line moving it can actually put together quite complex images. In fact flatbed scanners have been converted to slitscan cameras too, but not by me. Not yet at least.

My preferred material to build these slits is the metal from an aluminium drinks can. This can actually be cut quite accurately with a sharp knife and steel rule. The technique is to cut the metal to size and then cut it in half, and it's important to ensure that you don't swap or turn over either piece after it's cut - any imperfections in the cut on one side should match the other side. The width of the slit should be as small as possible and very even - don't allow the slit to be wider at one end that the other as this will give different exposures and sharpness. A with of below 1mm is ideal. I estimated mine were about 0.2mm.

The next things to arrange are the shutter, which must be held open, and some mechanism to wind the film past the slit. For my early attempts I wound the film by hand using a home-made rewind crank of very exaggerated size.

Modified Petri TTL

This works pretty well. The main disadvantage is the camera must be on a tripod. But there is something quite satisfying about winding and panning the camera with one smooth motion both about the same speed. Since most cameras have nasty wind-on locks and double exposure prevention devices, the technique I used was to shoot the whole film blank with a lens cap on the lens, then somehow arrange the shutter to be open (on B perhaps) with the rewind button pressed, and rewind and pan the camera simultaneously. Some photographs taken this way are almost normal.


As an alternative to panning the camera, you can arrange the camera is still and the subject moves. That's how these two cars were shot.

Two cars

The same principle is used commercially for cameras that take photographs of horses, greyhounds etc as they pass the winning post. Notice that as the camera is fixed the background is blurred in a characteristic "horizontal" way as the camera only sees a very thin slice of background repeated.

A combination of panning and taking pictures of moving objects can give surprising results. For example, one of the cars was moving here, making it appear much shorter than the car behind. In fact you can see both the front and rear of the car behind, with the car infront only covering the middle.


You'll find plenty of other very wacky photographs of this type on the web.

Conclusions and further developments

There are some problems with this method.

The exposure is governed by: the speed of the film as it goes past the slit and the width of the slit. It is quite easy to calculate that if the speed of the film is V mm-per-second and the width of the slit is W mm then the effective exposure is W/V seconds. For this to be something "sensible" like 1/100 the slit needs to be very narrow.

The slit should be narrow for another reason: the narrower it is the sharper the images will be. Sometimes the panning and the speed of film match exactly, and the images are unexpectedly sharp, but more often one gets slightly blurry images which may be good enough or not, depending on what you want.

I find it is difficult to cut any slit completely evenly, which accounts for the horizontal lines seen in many of my pictures. It is also difficult to wind film evenly, and unevenness in this accounts for vertical lines.

The slit does introduce the chance for the film to get scratched. In fact this is a minimal problem compared to the others, but it is a problem.

Finally, as I have described it, these cameras need a tripod.

On the other hand, these cameras have the advantage that the pictures they take are not limited to the width of a normal frame on 35mm film, but can be as long as you want. Panoramic photographs are very much possible.

I future posts I will give some other ideas that simplify the process and make the cameras easier to use. This involves perhaps using a motor to wind the film. There are also ways to simulate slitscans with a digital camera that can take video. You may also find that your camera's focal plane shutter already behaves as a slitscanner, or that your digital camera (especially phone camera) works so slowly it too behaves as a slit scan. Watch this space!

Wednesday 17 August 2011

Gum Bichromate

If photography is art, the qualities of the media used in the final print are as much part of that art as the subject. In fact I would go further - the subject and whatever it is provided it is looked at freshly with an interesting eye is not important for "art". One does not have to take a photograph of a pretty girl or a cute puppy for it to be art: in such cases these cutsie subjects are more likely to be distracting from the purpose of the image than complementing it.

So other methods for making a photographic image on paper must be explored by any serious photographic artist. Or so my humble opinion goes. I am only at the beginning of this exploration, but I hope to share some of it here, and some details of the experiments I made.

The gum bichromate process appeals to me for a number of reasons: one uses real-art paper, and real-art paints (watercolours). The choice of colour is available in a bewildering range, and it is even possible to layer several colours on each other. The theory is that the dichromate chemical when exposed to ultraviolet light, hardens many natural and artificial gum or glue-like substances, and this can be used as the basis for making a print from a negative. An introduction to gum-bichromate is available at The Alternative Photography site and this site has much more than I can say here. However my personal experiences may be helpful.

The recipe

The recipes I read on the web were mostly of the sort "take a dollop of this and a small amount of that..." and were too imprecise for anything but experiment, not that there is anything wrong with that, but some precision is needed to help make the process more predictable.

I took some "half-pan" watercolours, student grade from an art shop, and chose one (for the first attempt, the black) and cut it into half. It makes a very thick gummy cube, rather difficult to spread without water, but I really don't want to add too much water as it is the reaction between the dichromate and the gum that is important. Ideally, the watercolour should go in a dedicated pestle-and-mortar. You might be able to improvise some alternative holder, or use paint from a tube which is easier to mix but less concentrated.

I dissolved 13g of potassium dichromate crystals in 100ml of de-ionised water. They don't dissolve very easily: what I did was put the crystals and water in a bottle, put the top on, then immersed the whole thing under the hot tap, shaking occasionally, until it had dissolved. See warnings on dichromate below.

I took 6ml of gum arabic solution (from a bottle supplied by Windsor and Newton, available in art shops) and mixed it and pounded it with the water colour. Gum arabic is from the acacia tree and is also available as powder - you could dissolve this in (very little very hot) water and use this instead. My notes say to use 30g in 90ml water, though I didn't test this.

In a darkened room - with definitely no daylight though some tungsten light should be OK - I mixed the watercolour and gum mixture with 6ml of the dichromate solution. This made a thick watercolour paint which just covered a sheet of A2 paper, using a good soft flat brush. The paper was stored in the dark to dry, and when dry cut into small pieces as required. I used medium quality watercolour paper. The textures in the paper will remain and add to the print, though very smooth paper will show more detail.

Printing out

Like most printing-out processes, the best source of light is the sun, but a UV light (from a fluorescent tube or mercury vapour lamp) is possible. The negative is place on top of and in contact with the paper, and the whole sandwich is held tightly under glass. There are special frames to hold all this together. I found that even on a rather dull overcast day, 2-5 minutes was sufficient exposure. In bright sun it will be less. This is much less exposure than is needed for printing out using silver-based emulsions.

Printing-out frames

Special printing-out frames are available to allow you to check the process as it happens. If you have them (I did) by all means use them, but in this process nothing appears to be happening and it is pointless checking anything. You just have to do a trial, develop it, and modify the time for the second attempt.

The UV light should have hardened the gum in certain areas of your paper, but as I said, at this stage nothing can be seen. To "develop" the picture you need to wash away the non-hardened gum revealing the white paper beneath. Run the paper gently under a stream of water from a tap for a minute of so. Then soak the paper image-side down in a tray of clean water for 5 minutes. Then change the water and repeat 2 times. I found that the paint needed some help to come away and I brushed the paper very lightly and evenly all over with the same soft flat brush I used for coating. When this works (and for me, it always worked, though some prints were better than others) it was wonderful to see how some paint comes away leaving the image.

After washing thoroughly (all of the orange dichromate colour should go) leave it to dry.

Study of yucca (gum bichromate)


The gum and modern pigments are safe to use but dichromate is toxic and probably carcinogenic. When handling crystals or powder wear rubber gloves, eye protection and a face mask so there is no possibility of breathing in dust. When handling solution or prepared paper use rubber gloves. If you use containers to handle chemicals don't use them later on for food. If you think you may have accidentally touched something with chemicals wash in plenty of running water immediately.

The paralysed cyclops

Just every so often a project - or even a single picture - is finished.

In most of the photography world, "finishing" a picture is (almost) just clicking the shutter button. The rest of the processing is a formality - whether it be film or digital. In the art world, finishing a picture can be a major event. In fact, many people say a picture is never finished, just "good enough". What is the difference?

Real art, I believe, is, as well as about looking and recording what is there, is about the processes of evaluating the marks placed on the paper, or canvas, and repeating them or re-doing them until they are right. This process of evaluation and development is what makes the difference between the fine qualities of marks or whatever seen in true art, and bad art or (sigh) most photography. One of my artistic heroes is Frank Auerbach who would paint over and over a painting perhaps a hundred times, most times each being only loosely based on what came before, but always looking for that elusive "finished" painting.

I have set up a companion blog for my "finished" work, The title comes from a statement by David Hockney, saying that photography cannot be art because it only has one eye (the lens). In saying this, I think he is wrong occasionally, but (sadly) this is right most of the time. I hope my finished photographs are the exception rather than the rule. Please look at it. All this talk of camera mods and hacks would be quite empty if there was not an objective, and it gives my best attempt at showing that objective.

Wednesday 10 August 2011

Distressing pineapple

I have talked about distressing negatives using bleach (hypochlorite) and also with wire wool already in this blog. Here is an alternative method that promises better control than either: pineapple.

Actually papaya would probably work as well. Both these fruits contain an enzyme that rather slowly dissolves gelatine. Gelatine of course is that jelly-stuff made from boiling skins and bones of animals, and is in fact the stuff that the business-end of a piece of film - the emulsion, that carries the actual image - is made from.

Apologies to vegetarians: film photography is not vegetarian. Non-animal products were tried at some point but obviously were not good enough. In the distant days of photography 100 years ago or more, albumen from eggs was used as an alternative, but that isn't vegan. I am reminded of the story of some very precious waif-like model who turns up at a photo-shoot with her nose in the air, prattling on about how important it is to be kind to animals. When she hears the photographer is using film she complains about the cruelty involved in making film, and refuses to have her photo taken, storming off in a huff. She doesn't even stay long enough to take her coat off (which is very expensive, made from real fur).

Anyway, and back to topic. Pineapple on film. It should work equally well with colour or black and white, slide or print film. I never heard anyone else try this, so it's all very experimental. Try it your own way, but use my suggestions or experience here as a guide if it helps. Here is what I did today.

I got a small very ripe pineapple and took about a quarter. (I eat the rest!) I turned the flesh to pulp in a liquidiser. I taped some negatives emulsion side up to a sheet of glass (any flat surface will do) and got a very soft flat brush.

Liquidised pineapple

Now the idea is to brush the pineapple onto the film so that only a very small amount of the emulsion layer comes away, and you can put textures in the image. With the film I had, I discovered leaving pulped pineapple on the film for about 30 minutes removed a bit more than half of the emulsion. Some emulsions are thicker than others, so you may get a different effect. You know when something is really happening fast when the pineapple starts to go a greenish black from the silver in the film. (This is for black and white film. Colour film will behave differently.)

This was the best technique I found. I dolloped pineapple onto the negatives very thickly and spread it round, left it for 5 minutes to let it start working. Then I brushed the emulsion very gently to remove almost all the juice. At this stage the negatives dried quite quickly and the emulsion was soft. I brushed in alternate directions with a brush dipped into a small amount of pineapple, and left it to nearly dry each time. I did this for perhaps 5-10 minutes. Then I washed very carefully and thoroughly, without touching the emulsion.

This is a negative as scanned before the treatment

The Shire, Birmingham

and the same negative afterwards:

The Shire, Birmingham

The effect is only just noticeable on the negative looking by it by eye, but of course it is very obvious in the final picture. If you click the image you should be able to go to a larger version. It looks much better up close.

Here is another, first before

The Shire, Birmingham

and after

The Shire, Birmingham

To finish with some thoughts and suggestions for more experiments: the interesting thing is the texture that is now on the emulsion. You can try anything at all make a texture when the emulsion is soft. My brush was just a start. I also wonder if the resulting emulsion can be dyed, and some image made because the other different densities from the thickness of the emulsion and the dye. There are also some chemicals that can inhibit the effect of the enzyme, and if you are chemically minded you can look into that and see if you can get them to do anything interesting.

Colour film will behave quite differently as it is made from several layers corresponding to the various colours. This is definitely one to try some time.

Finally, some warnings. Pineapple juice is of course safe, and tasty, but black and white film contains silver which is poisonous. Colour film contains treatment agents to stop it being attacked by fungus, and formaldehyde was a common choice at least a few years ago. This is poisonous too, and film may also have residual chemicals in it. Keep food and food items away from photographic items. Also, I have no idea whether film treated this way will remain stable over a long period of time. It probably depends how carefully you wash it.

Saturday 23 July 2011

I'll be back soon with more

I am going to be away on holiday for two weeks from tomorrow, and won't have time to post anything else today. There'll be more when I am back, or you can always look at my Flickr pictures at for a sneak preview of some of it.

Miroslav Tichý

For now I shall just leave you with some words from the Czech photographer Tichý.

Photography is painting with light! The blurs, the spots, those are errors! But the errors are part of it, they give it poetry and turn it into painting. And for that you need as bad a camera as possible! If you want to be famous, you have to do whatever you're doing worse than anyone else in the whole world.

Friday 22 July 2011

Adding a filter ring

Old point-and-click film cameras like the famous "viv" and others are great, but there are a couple of obvious problems with them.

  • There is no exposure control: no alternate shutter speeds or apertures
  • There is no focus

All this can be easily changed with a very very easy mod. It will turn your cheap toy camera into something quite capable.

All you need do is add a filter ring.

Filter threads

A filter ring is just a threaded ring of metal taking a filter in one of the standard sizes. The standard sizes are all metric. Common ones are 46, 49, 52, 55, 58, 62... This means the diameter in mm of the thread. Actually another dimension is required: the distance the thread travels when it turns once round. For filters this is almost always 0.75mm. Thus you see filter threads written M49x0.75. (The M is for metric.) This is the same system as for the famous M42 lens mount. The M42 lens mount is in fact M42x1 as one turn advances the thread 1mm. In contrast the T2 lens mount is M42x0.75. That's why T2 lenses don't fit M42 cameras directly: an adapter is required. Unfortunately I see lenses sold on the bay as "M42" when they are in fact "T2".

To get or make a filter ring you need to take threaded a part of a lens or filter and remove all but the ring. In particular remove the glass. The first time I did this I smashed the glass because I couldn't see how to do it. Then it became clear. (No pun intended:) Some filters have a fine slim threaded ring that holds the glass in place and this can actually be unscrewed with something fine like a pair of jeweller's screwdrivers. Some have a sprung metal loop that has to be prised out. None I have seen is attached with glue.

Alternatively you can buy a stepping ring which is like a filter ring but with different threads on each side. Get one with the right size (M49, M52 etc) and right gender (male, female) that you need on one side. The other side doesn't matter. A step-up 49-52 ring has a male 49mm thread to screw into the front of the lens and a female 52mm thread to accept a 52mm filter. A step-down ring 52-49 has a male 52mm thread to screw into the front of the lens and a female 49mm thread to accept a 52mm filter.

Simply glue your ring on to your camera with epoxy adhesive. (The sort that comes in two tubes that you have to mix.) It helps if you scratch any shiny surfaces hard with a sharp knife or screwdriver first to ensure they will take the glue. Leave to set overnight and you are done.

For example

Vivitar ultra wide and slim with added filter ring

here I used a 37-46 step up ring, and

1950s Coronet 66 with added filter ring

where I used a 52mm ring salvaged from a broken camera

What to do with your modified camera

There are two or three main benefits of using filters. First is exposure control.

  • You know what speed your film is. You know (or can probably find out from the web) what the fixed shutter speed and aperture of your camera is. So with a light meter you will know how many stops your picture is going to be over exposed. Don't let it happen! Use a ND (neutral density filter) to stop the light by 1 2 or 3 stops (using a ND2, ND4 or ND8 respectively). Or (with care, getting the orientation right) you can use a polarising filter.

These cameras work so much better when the the light is just right and the film is being used to its best.

If you are using black and white film...

  • Try a coloured filter to get some different tonal effects!

For example an orange or red filter will make blue sky darker leaving white clouds white. If you also get the exposure right, a red filter can make deep blue sky almost black. A green or yellow-green filter is great for making leaves lighter.

  • Use a close-up to focus on nearby objects!

More on this in a moment.

If your filter ring is large enough, as it probably is, you can easily stack filters to get all these effects. If you are using black and white film your coloured filter will change the amount of light too, so if yuo are desperate or happy with the colour, you can used a red or orange filter like an ND8 or ND4 filter.

Using close-up lenses

Close-up lenses are one of the most common accessories and least understood. For my first serious camera I had a close up lens and a table of values of the form "with close-up +1 to focus at X set lens to Y". This is tricky and the table is nearly impossible to carry in one's head, or calculate on the spot, and is always left at home when you need it.

But the actual estimations you need are easy.

Let's suppose your fixed focus lens will "focus" from perhaps three metres to infinity.

  • A +1 lens is (as we discussed already in this blog) a lens with focal length of 1 metre. So the same lens with the +1 adapter added will focus up to but not much beyond 1 metre. It will focus from something closer than 1 metre to 1 metre itself, corresponding to the range 3 metres to infinity. In fact, with +1, 3 metres corresponds to 0.75 metres (I just did the calculation) so with +1 you get 0.75m to 1m.
  • A +2 lens has focal length of 500mm. So your lens with the +2 adapter added will focus up to but not much beyond 1/2 metre. It will focus from something closer than 1/2 metre to 1/2 metre itself, corresponding to the range 3 metres to infinity. In fact, with +2, 3 metres corresponds to 3/7 metres so with +2 you get 3/7m to 1/2m.

And so on. I can't calculate any more. But I don't need to. I just need to know that +3 focuses up to 333mm and +10 focuses to 100mm. (These are distances from the close-up lens to the object, not the camera to the object.)

Let's see this in action. The following were taken with the Vivitar Ultra Wide and Slim (a really great toy camera with a wide 22mmm lens) with close-up filters focusing close and throwing infinity out of focus

Face to face Languishing Raining sunshine

I hope you agree that these are much more interesting, with better focus close-up - but mainly because of the lack of focus at infinity. Large depth-of-field isn't everything!

Scratching at the surface

I feel like I am only beginning to scratch at the surface of the list of camera tricks I want to share. But I don't want to get fixed on any one camera or device - like the big 20x24 camera. And talking of scratches, scratching or damaging film has so many possibilities.

Here is one I did a while ago.

Life on the edge

This was taken with an old 35mm SLR film camera, a standard lens and one of those fish-eye converter lenses that you put on the front. (They used to be, and sometimes are still called semi-fisheye lenses.) That's what makes the horizon curved and higher in the middle (I was pointing the camera down.)

Semi-fisheye lenses

Semi-fisheyes or fish-eye converters are designed to be used in conjunction with another lens (this is why they are "semi-") but can in fact be used on their own. (That's something else for later.) They are also very useful as bits of glass for lens hacks (more stories for later). I have picked up several, mostly about a tenner a piece, at various camera fairs or on the bay. If you add to that a tenner or so for a film camera, that's 20 quid for a fish-eye camera that is ten times better than the fancy-priced Lomo fisheye camera that costs more than twice the price. Which would you prefer?

If you use a semi-fisheye you need to know that you must stop your lens down small (to f/16 say) to get anything like acceptable sharpness across the whole frame. Or you can use your lens wide open to get that dreamy effect with the centre sharp and the edges blurred. You won't get a 180 degrees circular image with a semi-fisheye on a standard lens. But you might with a semi-fisheye on a wideangle lens.

Using an ultrawide lens is great for candid shots. The people near me had no idea I was taking a picture of them, as it looked like I was pointing in a completely different direction somewhere at the distant horizon.

For the image above the light was bright and I could stop down. But I wanted to make the image soft and interesting in a different way, so I took some wire wool (very fine) and lightly scratched the negative before scanning it. A little goes a long way and if you want to try this start by scratching very very light with very very fine wirewool. Or you can use the sharp abrasive side of a washup-pad, or (gently) some abrasive cleaning cream on the non-emulsion side. Whatever you do it is bound to be creative and interesting. Try to make your scratches match the image - either circular, or all in the same direction.

I cropped the image to avoid the circular edges, and scanned. I scanned the black and white image, but told the scanner it was a colour negative. The scanner cave me nice colours which I manipulated in the Gimp. Sometimes scanners give two-coloured images when you scan black-and-white as colour, one colour for the background of the negative and one for the silver in it. It's often worth scanning as colour. (Even as colour slide.) You can always photoshop it back to black and white if you want later.

Distressing with bleach

There are other ways of damaging negatives to good effect. In the next one, the negative was damaged using common household bleach (sodium hypochlorite, or "thin bleach", not to be confused with what is sometimes called "thick bleach" nor with what photographers sometimes call "bleach").


This process was rather more random. It relied on a bit of luck: bleaching the negative until two of the negative layers were removed, but the third remained, and the way the scanner (and my post processing software) treated it. The bleaching effect was different near the sprocket holes in the film, which is what causes the painterly-like brush strokes in the sky.

Using auto-equalise

For those that use the Gimp or other equivalent photoshop-like programs, some very interesting mixed film/digital effects can often be got by taking a picture with almost no detail and post-processing it. You take your picture, by perhaps massively under- or over-exposing, or perhaps by removing much of the detail (as I did here distressing the negative), or you photograph using old film that's no good, or in some other way. Then you scan what looks like an appallingly bad negative. You might usefully scan it as if it were colour when it is in fact black and white, or as slide when it was negative, or both, and use "auto-equalise colours" in software.

The way it works is this. Your original has a little detail in the image itself but not much. And what it does have has been produced right on the edge of what the film was designed to do, so is likely to be much less than perfect. But there's lots more going on in an analogue negative: grain and grunge and whatever. What auto-equalise does is expand this detail to fill the whole tonal and colour range. It exaggerates all the tiny nuances on your negative, which are often scratches or blemishes, or poor tonal or colour rendition of the film that was already pushed to its limits, and makes them become amongst the most important features of the image.

Another way of understanding what's going on is that it is the combination of the digital and the analogue. The analogue processes introduce imperfections that are exaggerated by the digital processes. There is not much information from the image itself, but there is information in the analogue imperfections, so all this information creates a rich picture. On the other hand, if you digitally make an image with little information and then amplify it digitally, you still get an image with little information.

A lot of what I like to do is push traditional processes to their limit, possibly exaggerating them digitally or using an analogue way later. You'll find out that a lot of what is done in photoshop can be done in the darkroom too.

Remarks on bleach

Sodium hypochlorite isn't terribly easy to find in the shops nowadays. It is safe when used properly (and has been used for hundreds of years) but can be dangerous when mixed in a stupid way with certain chemicals. You don't mix it with thick bleach, or acids or strong alkalis or some other things like hydrogen peroxide. It isn't particularly environmentally friendly either. I get the impression that the powers-that-be (who think we are all stupid and are going to kill ourselves or do something criminal) are making it harder and harder to get. This is very bad. But I have some ideas of other chemicals to use instead, but that will definitely have to wait until I have done some more experiments.

Thursday 21 July 2011

Yesterday's photo

Here's the photo I took yesterday.

Garden study

There are lots of things wrong, most notably a light leak that comes as a big white splodge on the right. But I was happy with this: because there's no similar splodge on the left. That means the film holder I made works on one side. When I worked out which side is good, which bad (remembering that the image on film is upside down) I could see that one side is slightly better than the other. So all I have to do is fix up the other side too, and that does not seem so difficult now I know that all I have to do is make it like the other one.

Experimental design

There's another tip here. Every experiment should if possible test only one thing. Then you know if it didn't work what was wrong. I'd already tested the film and the developer I was using in another camera and knew that was fine. So that eliminates one possible source of problems. And so on. It's sometimes tempting to rush ahead and try lots of new things all at once, but it doesn't always pay in the long run.

There's something else strange about this photo, but not really so strange because I'd seen it before somewhere else and was half-expecting it. That's the big sideways-on moon-shaped curve at the top. This is because the lens I was using didn't "cover" the huge negative. This is a common problem with large cameras and easily identified. In fact some photographers made it almost a trade-mark, and used such vignetting due to lack of lens-coverage as a feature of their pictures. Eugène Atget was one such photographer.

In my case, I'd rather have this vignette when I choose to have it, and not leave it to chance. That means I will have to modify something to get rid of it, possibly introducing it again when I really want it. But I was surprised it was so noticeable - I was expecting the lens to very nearly cover the negative. When I had put this lens together I had calculated what to expect, and it wasn't supposed to be this bad. I checked my calculations, they were OK. Eventually I decided to check the +1 close-up lens I was using.

The focal length of a lens

A good quick way to estimate the focal length of a lens is to project an image of the sun (which is effectively "at infinity") onto board or paper and measure the lens-to-image distance. (I will have to say more about this later too.) In my case it was about 650mm, and the lens was supposed to be +1 dioptre or 1000mm. That's appalling - very inaccurate. Soon I will be measuring the focal length of some of my other lenses to see if they measure up to what the manufacturer says.

When I redid the calculations with 650mm they came out in line with what I had observed. Again this is bad news in a way, but good in that one more variable has been eliminated. And so it will go on.


To finish today, here is a detail from that 20x24 image.


Close-up you see a nice feature - lots of little scratches on the film. This really is an interesting film-hack to know about. There are some wonderful effects with scratched film that would take a photoshopper a month of Sundays to make. (Or do you buy things in photoshop?;) But again, I don't want them all the time so I will have to investigate. There's a clue - all the scratches are parallel. That means I think that they were made when the whole film slid as one piece either cutting or mounting the film in the holder. Another thing to investigate.

Wednesday 20 July 2011

I took a photo today

I took one photo today, and I am exhausted but happy.

This one photo is with my very biggest camera. It takes negatives that are 20x24 inches (500 by 600mm). Although it's not strictly speaking a camera mod, it's definitely a camera hack, and it deserves a place here, though it is my most ambitious project so far, and it will take a while to explain all the various parts of it.

20x24 is the largest size negative for which is it still comparatively easy to get normal film. Adox black and white film is one possibility. It is just over £150 for ten sheets. When you think that a single sheet is about the same amount of film as six 24-exposure 135 films (35mm) £150 isn't too bad really. But it's frightening to know that that so much film can be used in one photograph.

20x24 cameras used to be, and still are, commercially made. Not surprisingly they cost five-figure amounts.

Now, I can't afford £150 for ten shots (let alone the price of processing) right now, but might consider it for special occasions. I certainly can't afford £10000 for a camera, so my 20x24 is done on the cheap. It's almost entirely homemade. The only part that I didn't make was a lensboard (and this was just out of laziness - I happened to have one that was suitable, but I could have made something out of plywood). The camera's made out of MDF with glue and paint and velvet, a large sheet of glass which I frosted myself, and the lens is some random lenses that have been put together in the home-made-lens style. The details will appear on this blog later.

The film is some printers' lith film that I got quite cheaply on the auction site in a roll, and I cut it when I need it into 20x24 sheets. It works out at about 50p a sheet. This kind of film is not designed for pictures but for hard-edged graphic use. So how it can be adapted for making pictures is another story to be told.

Of course you could ask (and are probably asking) "why?" Well again, it fits the overall story here: modern cameras are just too good and I want an interesting bad camera, preferably one that takes interesting pictures that no other could. There are plenty of ways my 20x24's pictures are quite different from those from your digital, or even your normal film camera. And I think with a bit of work they might sometime soon be better, in their own way. I'll have to convince you of that later too.

So all this is for more detailed explanation later. Probably what you want most of all to know right now is what the camera looks like. Well here it is.

Front of my 20x24 camera Rear of my 20x24 camera

It's not something to put in your pocket. It's not something you'd use to take a picture quickly. But perhaps it will produce pictures that are rather different.

This is what I did today.

  • Cut a sheet of film and loaded it into the film holder. (1/2 hour)
  • Set up the camera, pointed it, focused the lens, measured the light and calculated the exposure. (1 hour)
  • Removed the glass on the camera and replaced it with the film holder. (5 minutes)
  • Took the picture. (15 seconds)
  • Put the camera away. (15 minutes)
  • Developed the film. (1 hour)
  • When film was dry, contact printed it onto a sheet of photographic paper. (1 hour)

When I am a bit more used to this beast, many of these tasks will be quicker, but that's not really the point.

This was my third picture with the camera, and I am still tweaking the camera, fixing the things that are wrong with it and making it easier to use. I can't show you the picture I took today yet, because it is still wet and drying. Nor can I scan it because my scanner is for A4 maximum. But sometime I will take a digital photograph of it.

Paper negatives

To save time, when I did my first picture with the camera I used a useful trick that can be really helpful for anyone messing about and learning on large format cameras. That is, I used a sheet of photographic paper instead of film. I'd done this previously with my (much smaller) 4x5 inches camera and it taught me a lot. The idea is that you miss out a major stage in the process - the film developing. And paper is much easier to handle because it can be done under red safelights, rather than full darkness. So for my first 20x24 picture it made sense to do it again.

Of course this results in a negative on paper. (Hmm: paper negatives. That's a good topic for later too...) For my 4x5 paper negatives it was easy to scan them normally and photoshop them (in the Gimp of course:), inverting the tones and adjusting the contrast or curves as you would do anyway in the darkroom. The results were really pretty good. Unfortunately I couldn't scan my 20x24 paper negative. But I did persuade a friend to take a photograph of me holding it up. And then I photoshopped this, inverting the tones and adjusting the contrast on the computer. The result is this.

My first 20x24 image

Tuesday 19 July 2011

From multiple exposures to slitscans

Here's a nice trick that will make the owners of a simple point-and-click roll-film camera proud.

These cameras usually have self-cocking shutters, which means the first stage of pressing the shutter release tensions the spring in the shutter, and only the very last bit lets the shutter go. (You can pride yourself on your wonderful shutter action. Most more expensive shutters work in two stages with a separate cocking lever and release lever that is much less convenient.)

And cheap roll film cameras rarely have fancy mechanisms to stop you clicking that shutter more than once on a single negative, like the expensive ones do. That makes these cameras really good to use.

The sort of cameras I am thinking of look like these:

Ilford Envoy (style 1) Coronet 6-6 Ferrania Ibis 66

They are essentially the point-and-shoot pocket cameras of the 1950s. Often they are very elegant and attractive. They are always interesting, and usually they out-perform a Holga or Diana. They are also usually much cheaper. (But a Holga or Diana would do if you have one of these. Or even a box brownie or something like that as long as it takes 120 film, rather than 620 film which isn't available, or 127 film which is difficult to get hold of.)

Multiple exposures

So all you do is click several times and take multiple exposures.

Either take two exposures in different places that you think will complement each other,


or try to hold the camera still (better still put it on a tripod, but sadly many of these kinds of camera don't come with a tripod thread) and take several pictures one after the other.


This blog is not going to be just a catalogue of cool effects though. It's also about how to make these cool effects cooler and better. So you are in control.

If you are doing multiple exposures there are two things to know.

  • Your exposure values must change. So if you are using two exposures on the same film, the film will see twice the amount of light. Four exposures is four times the light. This means if you think ISO400 film would give you good exposures one particular day, double exposures on ISO200 film should be about right too. So would be a quadruple exposure on ISO100 film.
  • The multiple exposures will tend to "muddy" the image. That means the various exposures will tend to even each other out to give a uniform grey. So: multiple exposures reduce contrast.

If you are in charge of all stages of the process you can do something about contrast. Push-processing (i.e. exposing film at high speed and increasing development, e.g. exposing a 100 film at 400 or a 400 film at 1600 and developing longer to compensate) increases contrast. Do this if you can. Or you can print your image on high contrast paper. Sadly both of these are beyond most people who send their film to labs: if you are one of these, expect to have to use a photoshop-equivalent to increase contrast on your scanned negatives.


Here's a variation of the same trick. Take a picture and then wind on the film and move the camera a little bit. Then take another picture and wind on the film a bit more and move the camera again. Carry on a dozen or maybe more times.

Such as here.

Bricks and blocks come

Or here.

Spaghetti skyline

(This set also had a light leak, which shows these are not unique to Holgas or Dianas either. More on this later too.)

If you are clever or lucky your panning might equal or nearly equal the movement of the film. (Hmmmm... which way to pan? it depends on which way your camera pulls film though. Don't forget the image on the film is upside down. Here's a puzzle for you. Which way should you pan your camera? The answer's easy if you can flip your brain into a mirror image and then turn it upside down.)

Quick trick brick stack Let's do tricks with bricks and blocks

Adding a slit

Finally, here's a camera mod, rather than just a different way of using the camera. For this very easy mod, cut some black card and glue it inside the camera making a small vertical slit maybe 5mm wide.

Modified Ilford Envoy

Then the click-wind-and-pan action only takes single exposures, albeit very long thin exposures. (OK you'll have to learn how much to wind. Maybe they will overlap or maybe there will be gaps. That's part of the fun.) With some practice, and perhaps some creative cropping you'll get something nice.

Oranges Passing a cycle shop

A very thin slit with a camera that's panning is the principle of a slitscan. If we can make the panning and the film-winding smoother, and the slit thinner, we get a completely different way of taking a photograph with a normal camera. This will be taken up later too.