Doubts about Leitax Mod (C/y to F mount), and using F mount lens on Alpha Cameras?


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May 28, 2017
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Cameras I intend to buy
1. Either A7R III or A7S III (A7SIII if it improves rolling shutter performance and has 4k60Fps, else A7RIII)
2. Minolta Maxxum 9 (I just want to explore film, and this is the only camera that caught my attention other than Mamiya 7).

Lens I intend to buy.

Nikon F mount
1. Zeiss Distagon 28mm f/2 ZF.2 (I wish there was a sony alpha variant of this, sadly it doesn't).
2. Nikon 105mm either f/2.5 AiS or f/1.8 AiS

Contax Yashica Mount
1. Zeiss Contax 35-70mm f/3.4

I need help with adapters and possiblities. I don't want any additional cheap optics between my lens and cameras (no fotodiox with lens).

Question 1:

I plan to do leitax mod to make the contax to F mount (if not possible, to alpha mount) so that all 3 lens are on same mount.
Zeiss Contax lens for Nikon cameras

Since C/Y flange distance is 45.5mm and F mount flange distance is 46.5mm, I'm wondering how they would be able to pull this off. Wouldn't it be cutting off some part of the lens, or just the mounting adapter size is large enough to make this feasible. If possible, Would I be losing anything when modding to F mount? I saw this sentence on this page "For Nikon cameras, we don't use the perforated ring, and we have to remove the aperture lever".
Vario-Sonnar 35-70 on Pentax

On the site was able to find Contax MM to F mount, is C/Y same as MM? Zeiss Contax lens for Nikon cameras

Since Alpha mount flange distance was 44.5mm (less than 45.5 for C/Y) I was wondering if it would be more feasible, but I'm more into making all lens F mount if it is possible.

Question 2:

Trying to adapt the F lens to Minolta. Is there any adapter available that I can hook up to alpha mount to be able to use Nikon F lens. The flange distance difference is about 2 mm, which I'm not sure will permit anything. I was wondering if there were good lens that will satisfy my needs in the minolta/sony lineup, but I could only find good ones that are in telephoto range. I couldn't find much to replace the 28mm or the 35-70mm for my purposes. So, I don't really intend to buy minolta lens to use the Maxxum 9, if adapters are not possible, I'm open to modding the Maxxum 9 from A mount to F mount, if such a thing exists. Yes I'll be missing autofocus part of the camera, but I'm fine with it (the lens are manual focus anyway). There's more to love about that camera other than just autofocus (film is very personal). Sure I can get a Nikon F body to go along with it, but once again film is preference. I'm open to a Nikon F film camera as a last resort if I can't make these work on minolta... I'm also open to canon FD mount film cameras (F-FD and Y/C-FD) then FD-E, but I'd prefer minolta!.

The last resort of course, is give up film, get adapters for each of the lens to sony E mount and go along with it. I'll be totally fine with it, but I'm hoping I can experience film with the same lens and wishing to find ways to do that with a camera that I'll enjoy using.

Other Doubts:

For A7 I know its definitely possible since their flange distance is very small and there's loads of adapters available. I am doubtful about one thing though, using an adapter after doing leitax mod on the 35-70mm, would it cause any instability (Mechanical/plane of focus wise)? I guess it won't be an issue, but just want to be sure.

And I'd like to know if any of these lens are radioactive (contain thorium or other toxic stuff). Yes I know that we experience natural radioactivity all around, but I just don't want to take additional risks, especially since I have pets. All of these are from 80s (except for the older f/2.5 non AiS 105mm - the reason I'm swinging towards the newer f/1.8), so I believe they won't have used thorium, but just want to be sure.

These lens just fit into my needs perfectly. All are relatively compact and inexpensive for what they do. I don't intend to travel ultralight, but I don't want to take extra weight for things I dont use (Autofocus, and image stabilization - I still have ibis when I really require it). I love the 28mm field of view for street photography/asymmetric things and quite often like shallow depth of field in that range (the field curvature of zeiss/leica lens make it even more shallower - I love it). 35-70, I don't require anything faster than 3.4, it'll be used for shooting objects, showing a reach from above a height (like for landscapes), and occasional macro - sharpness and contrast is key here. And 105mm for portraits. I'm open for alternatives, especially in minolta lineup but I couldn't find much that sing to my wishes like these do.

Manuel Jenkin.
I'm interested to know modding the Contax Zeiss 35-70mm 3.4 from y/c to nikon F mount makes anything worse - focus breathing, Aperture stopping, etc. I'd be using it for video purposes so I'm concerned about focus breathing. I saw a video here that showed some adapter thing (not leitax mod I guess) in which probably the aperture pole was scratching some part of the body of an Canon EF camera and he wasn't able to stop down the aperture below a certain point when mounted to the camera.

The mod looks quite extensive (even compared to other leitax mods), but I'd be willing to do that if I'd be getting the same lens with same performance characteristics, just in a different mount.

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