I recently re-purchased a Crown Graphic special with the Xenar 135mm and would like something that is much sharper to be used with the existing 135mm cam. I want to mostly use it with the rangefinder for candid pictures and scale focus at f16/f22 with and without flash. I know all 135's are different but at f16 or f22 they should all fall in the depth of field or am I wrong?
I don’t know if I’d count on it. Different lenses of different designs will have different back focus distances.
How much adjustability is there in adjusting the focus cam? I’ve never used a crown. You may want to do some research to find lenses with the same back focus.
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-Chris
Simply repeating what I've read: swapping out lenses, even if same (front?) focal length, doesn't guarantee the cam will work. Probably due to reason stated above. Also heard that the Xenars vary from specimen to specimen. Some are considered good by some. I have one in my newly acquired Crown and it seems sharp to me. However, I am super new, so I don't trust my judgement on this element, pun intended!
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Um, er, ah, the cams are measured focal length-specific. Focal lengths engraved on lenses' trim rings or barrels are marketing focal lengths, are rarely equal to the lenses' actual focal lengths as measured.
OP, if you want another 135, fine, but be prepared to find or make a cam to suit it.
If I were you, OP, I'd check RF calibration -- are the bed stops in the right place? does good focus per the RF coincide with good focus on the GG? -- before giving up on the Xenar. I'd also check for operator error. When I was doing extensive lens testing, I found that much more often than not the reason a lens failed acceptance testing was me, not the lens.
Christopher, all that's needed to set up a Graphic top rangefinder for a lens is setting the infinity stops -- also called bed stops -- at the lens' infinity position if the RH has the right cam for the lens. I used to believe that more work was needed, eventually found that I was mistaken. Oh, and by the way, back focus is the distance from the rear element's vertex to the film plane when the lens is focused to infinity. I think you meant the flange-focal distance, the distance from the rear of the shutter or barrel lens' flange when the lens is focusted to infinity. Minor quibble, but still ...
Unless that Xenar has some unusual defect, you are not going to improve your results noticeably with another lens on the Crown Graphic. Be sure your own RF is in accurate adjustment, many of them are not.
Unless your Xenar sample has an issue, it should be as sharp as a modern 135mm lens. Typically they are very sharp, they just have limited coverage that makes them perfectly fine for your use, but less so for landscapes. I know people view top mounted rangefinders as being a plus, but the ability to fine tune to a particular lens without messing with cams has been a reason I prefer the side-mount Kalarts.
Just another two-bit opinion, but the Xenar I had long ago was a turd. Not sharp, but soft. Plus, a modern lens will be multicoated offering additional contrast to your images.
As for the cam, and again this is a two-bit opinion as my experience with these cameras is limited (I've owned 5, but didn't use them much), it is bound to the focal length and not the back focal distance. The back focal distance is just an offset. I think if you adjust the offset by setting the infinity focus properly, then the cam focus should be fine as long as the focal length of the new lens is the same as the old lens. Easy enough to find out. Try one.
I think I will just take more pictures and see what I get and I will double check the rangefinder and gg for focus outside in good light. I came across a 203mm Optar with graflex lensboard, infinity stops and a cam for about $200 and may get that instead. The little reading I did it appears to be a nice lens. I have no way of knowing if the cam is original to the lens but I assume if I set it up for infinity with this cam and check the gg and rf I should be good to go. Am I correct?
It's a more complicated than that. TRF cam-coupled lenses were set up by the factory in one of two ways, with "hard stops" or "soft stops". With hard stops, the stops are set to infinity focus with the camera track back hard against the bed stops. The RF was then adjusted to indicate infinity. This is the way a new camera with a supplied lens was set up. However, because the cams supplied with additional lenses might indicate something other than infinity if set up this way, the soft stop set up was used. With the cam in place, the camera was adjusted so that the RF showed infinity, which might not and probably was not with the track back hard against the bed stops. The track was then locked down and the infinity stops set for the new lens. Someone who knows what he or she is doing and has an unmolested camera, including correct ground glass/Fresnel, to work with can set up a TRF Graphic on hard stops with very accurate cams for lenses from 58mm to 360mm tele, operationally far superior to the Linhof Master Technika, and much lighter and less expensive. But for others, I suggest you work with a simple field camera or monorail and avoid possible disappointments.Originally Posted by campy
Perhaps you get whatever lens you want and make a custom cam for it: https://graflex.org/articles/oakes/
-Chris
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