Using enlarger lenses

On "full frame" 35mm cameras and digital cameras with full frame sensors, the focal length from about 75mm to 100mm is incredibly useful, and not just for portraits, which is what many people think of this kind of lens as being "for". These lenses helps in composing, by being a little more selective in the view, but without losing the perspective completely. They also help by giving pictures a narrower depth of field.

Unfortunately, in the 1970s and 1980s, from whence most of our second-hand prime lenses come from, lenses of this type were not so common: the typical amateur seemed to jump from 50mm to 135mm and the space in between was a limited niche for professionals with a lot more money available. The result is it is quite difficult to get inexpensive lenses in this rather useful range.

I have been experimenting with alternatives. One of these is to use enlarger lenses, which were made in 75mm, 80mm, 90mm and 105mm focal lengths for medium format, and are now very easily and cheaply available.

Enlarger lenses on full-frame 35mm

Here I have used an old Olympus OM10 as my camera body. You could use any SLR or DSLR. The automatic Olympus cameras had an advantage that is quite useful: since they meter light off the back of the shutter curtain and off the film the actual settings presented to the camera by the lens are unimportant, so there's a better chance of getting accurate exposures. But other cameras will be able to get the exposures by other means.

The first, and main difficulty is to mount the lens. Enlarger lenses typically used a "Leica screw mount" or L39 mount (sometimes called M39, but that's not 100% accurate). I took a flange from an enlarger and the metal mount of a broken lens and glued them back to back to make an adapter.

With the adapter you should be able to mount the lens, but be careful it doesn't foul up the SLR or DSLR's mirror. (Some enlarger lenses protrude quite a long way back, I found.) The main problem is now setting the lens the right distance from the film to achieve focus. You might have extension tubes or bellows that will help here. I used an old L39 extension tube with a 75mm enlarger lens in this set-up.

Don't be put off by the fact the enlarger lenses are often quite small.

As it happens, that gives me infinity focus. There is a tiny amount of adjustment available by screwing and unscrewing the lens a little way in the adapter. Or you can change the extension tubes you are using, or else get used to walking backwards and forward to get your subject in focus!

Don't forget the closer the lens is to the camera the further away it focuses, up to "infinity focus" after which bringing the lens still closer will not help focus on anything.

Enlarger lenses differ in their best focusing position. You will have to experiment. Sadly, it seems that the lenses of the most useful focal length want to be rather too close to the camera to allow a bellows to be used instead of extension tubes. But you may be lucky.

In the following I used a bellows with a 90mm lens.

The real advantage of the bellows is that it provides a focus control. As it happened, the bellows held the lens too far out to focus on infinity. That might not have been a problem if I was using the lens for portraits, but to get infinity I used an old friend - the negative telek lens I used a couple of posts ago. The telek (attached to the front this time) increases the focal length to about 100mm, a little longer than I wanted, but at least it gives infinity focus with this particular set of bellows.

My results from these lenses today are still drying after having been developed. I'll post an update shortly with some of them!

Camera fair challenge

There will be more on the epidiascope shortly. Today was the day of the Wolverhampton Camera fair, and as usual this was a lot of fun. And to spice it up a number of us made each other a challenge, which is the subject of this blog post.

Under a tenner

The challenge was to buy kit for under £10 and use it to take a photograph that very afternoon. That means there's little time for tinkering or mending and using additional kit from home is cheating.

One approach would be to get a cheap throw away camera. Another was to get a toy camera such as a Diana or similar, or a semi-working 35mm camera. Light leaks if any would be part of the fun.

I decided to put together an antique 1/4 folder from broken parts. I picked up a broken body with no lens or film holders and a cracked glass screen for £3, a old lens (not original to this camera, in fairly poor condition with non-working shutter) for £2, and from a separate stall got a small set of rather rusty plate holders for £2.

A number of people at the camera fair today had quite a lot of old glass plates for sale, and I love using these. I did a lot of searching in dealers' junk boxes and eventually bought a pack of 12 for £2.50 and that brought my total to £9.50 for the challenge. Unfortunately, in the heat of the moment putting everything together over lunch, I couldn't figure how to load the plates into the holders. Eventually I gave up and used some antique sheet film I had brought with me instead (bought on ebay for a similar price).

I used the film on the right. As you will see shortly, I would have been better with the glass. But the holders had metal sheet film sheaths in them, and these sheaths had rusted tight so I couldn't see how to get them out. Pity. (The sheaths come out by pushing them down against the spring at the bottom. A strong fingernail was needed to undo the effect of the rust gluing the pieces together.)

Putting it together

The lens and shutter goes into the obvious hole in the front of the camera and are held in place by a retaining ring. This ring was very difficult to turn, and I had to leave the lens in a somewhat wobbly state. (In fact, I found later it was not the correct ring as it had the wrong thread. What you get from rummaging through junk boxes.) I improvised a film canister lid as a lens cap and shutter. And loaded the film into the holders in the dark bag I had brought with me.

At least it's starting to look like a camera now!

I was lucky that the lens (a Beck Mutar 4.75 inch) I had picked was only a centimetre shorter in focal length than the one the camera was designed to take. So I could focus reasonably well onto the broken screen.

The plan was to use the lens on its smallest aperture (f32, or so the shutter said) and use the improvised lens cap as shutter for exposures of about 1s. This was rating the film at about 20ISO. The first attempt was a failure as the film came out of the holder when making the exposure. (It seems the holder is a little too large for the film, or the film too small. Both say 3.25x4.25" but the film does date 50 years after the holder.) I just about managed to succeed to make the next two exposures, but the fourth also suffered from the film coming out of the holder.

Results

I hardly expected the results to be hi-fi.... Note that I trimmed the negatives to be long and thin so that I can scan them with my 120 film scanner.

This was taken with the camera on the ground, and the lens wide open. At least it's recognisably an image...

This has a bad mark SE to middle E where the film accidentally came out of the holder and got folded when I returned the darkslide. It is also fogged at the top because the dark slide didn't go all the way. Ho hum. But at least it has some life to it, and apart from the film problem mentioned there are no other obvious light leaks or problems!

The delights of lens making

The mod described here will introduce you to the delights of making your own lens for your SLR or DSLR.

You need a camera that takes interchangeable lenses for which the viewfinder works through the taking lens. That's a (D)SLR. The shutter of your camera must be in the camera itself, not the lens, and accessories like extension tubes and bellows should be inexpensive. This rules out most medium format SLRs, which isn't much of a problem. If you don't have a digital SLR you can buy a 35mm film SLR for around £10 on the auction site or at a car boot sale. With the right choice of camera, the accessories you need will also be very inexpensive.

But hang on. Lens-making is very difficult!

Lens making is difficult, simply because of the technical, engineering and mathematical task of putting together a lens that views the world perfectly as it scientifically should. But don't forget what we are doing here. We are trying to use our cameras to produce images that are not perfect. That means our lenses need not be perfect. As long as they focus they should be fine... Actually, who says anything about them having to focus?

Here's one made with a home-made lens that doesn't focus:

You can try anything, and it is bound to be unique and individual.

By lens-making I don't mean grinding the glass by hand. I mean assembling pieces of glass you've collected from broken cameras or other sources (maybe a magnifying lens from the local market) and using these.

The hardest part is in making some sort of mount for the glass that attaches to the camera and holds everything rigid in the right place. In this blog I am going to suggest what I think is the simplest solution to this problem, using standard parts that are easily available. This isn't necessarily the cheapest solution, but it won't break the bank either.

Close-up lenses

So-called "close-up filters" or "macro filters" are usually nothing more than magnifying lenses set in a mount with a screw thread. That's half the task done. All we need is to attach it to a camera.

Reversing rings

Fortunately, a special gadget called a reversing ring does just that. Almost. Actually a reversing ring wasn't supposed to attach a filter to a camera directly, but was supposed to attach a normal lens to a camera the wrong way round. (That's the "reversing" bit.) So the ring screws into the camera and accepts the thread on the front of the lens. This is the filter thread, and just about all filters are "double threaded" meaning they have threads on the front and back. So with a reversing ring you can also attach a filter to a camera, the wrong way round.

The lens-police aren't going to notice if our filter is the wrong way round. (But you might notice something subtle about the differences for your particular filter - more on that later.) So with the reversing ring we can use our close-up filter as a lens. But when we look through the viewfinder everything's fuzzy. Can't we do better?

Bellows

Well yes, but we need to focus. Which means move the close-up filter the right distance from the film or sensor. For most close-up filters this means moving it further away, and the trick to do that is to put a bellows between the reversing ring and the camera.

When you do this you get something like this.

Here comes a wee bit of mathematics. The right distance for the filter to film/sensor to use is the focal-length of the lens. (For focusing closer objects you will need a little bit more than the focal length.) close-up lenses are called +1, +2, +3, +4, etc, with 1,2,4,10 being the common sizes. The +1, +2 etc number is the reciprocal of the focal length, in metres. That means +1 is 1/1metres = 1000mm. +2 is 500mm, +4 is 250mm and +10 is 100mm. The +10 makes quite a useful lens this way. It produces a very soft image and is slightly "long focus" so is good for portraits. Here is it in action.

An alternative approach to using a single lens is to combine several close-ups. A +4, another +4 and a +1 makes (effectively) a +9 with a focal length of around 111mm. Here is this combination.

Which gave this.

Suggestions for which equipment to buy

I will close by saying a few words about choice of equipment, especially with a view to reducing costs.

The bellows will be the most expensive item. Bellows are made for all cameras, and perhaps you have bellows for your camera already, in which case use those. The cheapest bellows to buy on the auction site is usually for so-called M42 cameras. These include earlier Prakticas, Pentaxes, Zenits and Fujicas, as well as a number of others such as some Yashicas. If you have a DSLR you will probably find that an M42 adapter is an inexpensive way to fit M42 attachments to your camera, so you should get one of these. Alternatively you should standardise on one of the more popular lens mounts, such as the Pentax K-mount, the Olympus OM mount, or a Canon or Nikon mount. This will reduce the cost and increase the availability of parts later.

You also need a reversing ring. For this you should as far as possible choose your standard filter thread size. Look at all your lenses and work out what filters they take. (49mm, 52mm, 55mm, 58mm, 62mm are common sizes.) Choose a size that works for your particular lenses. If in doubt choose the one that works for your standard lens, rather than the others. (For example, I chose 49mm as most of my lenses near 50mm have that filter size.) Now get some close-up filters in this size and a reversing ring to attach them to your bellows.

It will help (for now) if your camera has through-the-lens metering or has automatic exposure. Most have this. Working out the exposure for other cameras will be a subject for later. (A little more maths is involved.)

This is just the beginning of the lens-making hobby. Be warned: it can get addictive. For much much more information, look here: http://www.flickr.com/groups/homemadelens/.