M42 adapter with focal reducers

[Christoffer Glans]

Just bought a cheap M42 adapter to use some old Yachica still lenses that were gathering dust in order to get some nice vintage bokeh for scenes that require some heavy "character". Problem is that I'm using a focal reducer on my Komodo and I can only focus up to infinity, but not infinity or else the back element starts to touch the glass of the focal reducer. Even greater, putting the focal reducer on a full-frame camera gives an almost 65mm feel to some old lenses, with a seriously cool bokeh character.

I'm trying to find out if there are other vintage lenses that do work with the Canon focal reducer, so as to not touch the glass elements while focusing. Is there a good source anywhere for vintage lenses and info about them?

 

[Björn Benckert]

The longer the lens the less likly it is to protrude inte the lens mount. 14mm lens is likly trouble where 100mm is not.

But lets not confuse extenders and boosters with sensor size. A booster does not give a 65 mm feel it only gives a wider and faster lens than you had before. Just as a 2x extender does not give a 16mm sensor feel it only gives a twice as long and half as fast lens.

When people swap from a 50mm lens to a 20mm lens its just called swapping to a wider lens / shorter focal length... Rarly you would call that lets go for a more large format look...

 

[Christoffer Glans]

A booster does not give a 65 mm feel it only gives a wider and faster lens than you had before.

50mm at F1.5 on an APS-C is not the same as 50mm on a full-frame with a focal reducer. You cannot find an equivalent wider lens for APS-C or even full-frame with that speed. I think this has been covered many times on this forum. Just like a 14mm f1.4 on full-frame cannot be reproduced on s35mm with the same wide open number.
As soon as you stop things down it's easier to "replace" it with another lens, but it still doesn't do what I'm describing here, as the interesting bokeh gets more interesting the more of the outer regions of the image circle you get. So, if a full-frame vintage lens covers more than full-frame, meaning, a focal reducer on a full-frame sensor that has almost perfect coverage, that would give you a square image barely touching the vignette of the image circle. It gets so wide that it's closer to what a 50mm would look like on 65mm/medium format. So the Yashica 50mm lens I have, used on the Canon R with the focal reducer and M42 adapter becomes close to what a 50mm on a Hasselblad is: comparison

But then it seems like some lenses protrude back while others don't. The old Canon lenses can't be used, but the Yashica 50mm works except when focusing to infinity.

I cannot get this image with any other lens. It's the Yashica 50mm bokeh on a focal reducer on a full-frame sensor. This look has never been seen because the lens was never designed to be used on this kind of wide image circle, looking like what a Yashica 50mm would look like on a Hasselblad (if it was rectangular instead of square). It's one thing just mathematically speaking of "replicating one focal length with a wider lens" and it "can" be done on most modern lenses except on wide-open fast and wide lenses. But it's a whole other thing to have a distinct bokeh look from a certain vintage lens and get these kinds of wide images on their image circle that was never meant to be used. This is about the artistic expression of those lenses in this way, I don't care if the Yashica, mathematically, could be replaced by a wider lens on a smaller sensor, you can't get this bokeh any other way.