It turns out that there is more interest than I ever would have guessed in using old (or not so old) manual lenses on Canon digital cameras. People adapt the old Canon FD series lenses in a variety of ways. They also use old Minolta (Rokkor) and Pentax (Takumar) lenses. Some of these old lenses are real gems, and there is a certain satisfaction that comes from "breaking the rules" when you use one of these on a modern camera.

As you might expect, the first issue is that the camera and lens are physically incompatible. By scrounging on Ebay, it is usually possible to find rather inexpensive adapters. In any case though, these lenses will neither autofocus nor respond to electronic aperture control. So you are back to focusing by hand (without a decent focusing screen) and setting aperture by hand. This restricts use of the camera to either manual (M) or aperture priority (Av) mode. Some adapters have a chip, which fools the camera in such a way that the focus system will give you a go/no-go indication of whether you are in focus or not.

Registration Distance

This is the distance between a reference surface on the lens mount and the focal plane where the sensor is mounted. On a canon EOS camera, this is 44 millimeters. Old canon FD mount lenses had a registration distance of 42 millimeters, so to focus at infinity these lenses need to be closer to the sensor by 2mm - a big problem. Some adapters solve this by adding a negative lens, which I have never been happy with. Other adapters omit the lens and are useful only for closeup (macro) work, which is often fine for what I want to do with these lenses. Other lenses (like the Takumar M42 lenses) have a registration distance greater than 44 millimeters, which makes everything much easier.

Takumar M42 mount lenses have a 45.46 millimeter registration distance. This requires the adapter to supply about 1.5 millimeter of thickness between the lens flange and the camera mounting surface. Reports claim that many adapters are in fact more like 1.0 millimeters in thickness, which allows them to focus beyond infinity. This is certainly better than being too thick and not being able to focus to infinity, but does mean that just racking the lens to the end of its travel will not produce infinity focus.


long Takumar lenses

This is wandering way off the topic of mineral photography, but what the heck. I was tempted to make an offer on a long lens (A Takumar M42 mount 500mm f/4.5). It was selling for about $700, which is a lot of money, but a relative bargain for a lens that would cost $5000 or so in a modern version. I talked myself out of it for several reasons. First of all, any lens longer than 300mm is really only useful for wildlife photography, sports, or just taking pictures of the moon. None of these are activities I am eager to pursue, so having an expensive 8 pound lens that won't focus close than 30 feet is not a good use of resources. I could perhaps see owning a 300mm f/4 lens (and I just saw an M42 Takumar go for $150 on Ebay). But if I stop and ponder, I already own one. I have the 70-200 f/2.8 L lens and the Canon 1.4x converter -- which would yield me a 280mm f/4 autofocus lens of respectable quality, so what is the point. A final thought is that I need to put the 200mm M42 Takumar on the M42 to EOS adapter and see how I like taking photographs with it before I invest in any other manual focus lenses like this.

85mm lenses

The Asahi/Pentax Takumar 85mm f/1.9 would make a great portrait lens. A fast mid range lens like this would make a lot of sense to have. The Canon 85 f/1.8 autofocus lens sells for $400 new at B and H, which is something to remember. The legendary and magical Canon 85 f/1.2 L sells for over $2000, which is sobering and awe inspiring. I bid on a Takumar m42 85mm f/1.9 -- it ended up selling for $278, which is hardly a bargain and once the price crosses $300, I think I would simply buy the Canon autofocus lens.

135mm lenses

A fast manual focus 135mm would also be interesting, maybe an f/2.0 Takumar?
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