Using Zeiss 50mm 1.4 C/Y mount on Pentax w/o adapter

thomasxie · 07-26-2011, 06:38 AM

I have been using my Zeiss T* 50mm 1.4 C/Y mount on Canon EOS with adapter for a while. However, I always want to try it on my wife's pentax cameras without pay the "expensive" conversion kit.
Here is what I did to use it on pentax. Two out of the 3 silver color metal pieces as show in the 2nd and 3rd pictures were shaved for a little bit. I put some tapes under the silver color mount ring (unscrew the 3 screws) to rise it up.
Now I can fit the lens on the K20D! You need to be careful since the lens is not locked on the body.

Attached Images

**interested_observer** · 07-26-2011, 07:47 AM

Good Morning, I certainly understand about wanting to use your lens on both the Canon and the Pentax bodies. From what I understand its an outstanding lens. There is a slight difference in the registration distance between the C/Y and K mounts - just enough that there is really no way to have an adapter fit one on to the lens and be able to mount it successfully on the Pentax camera. The two mounts are extremely close to each other, which in a way is understandable since Zeiss either helped (K) or fully designed (C/Y) both of them in essentially the same timeframe.

On the other hand, there is a rather large difference between the registration distance between the Canon and C/Y mounts, which makes an adapter possible on a Canon body.

I only wanted to use my Contax lens on the Pentax body, so I went the "expensive" mount replacement route. I do not know that Leitax is making a small fortune on making and selling them. There appears to be a lot of machining in terms of making the mount and the tolerances appear to be relatively tight. The material is not cheap - its a good grade of stainless steel.

Rico here on the board has indicated a couple of times, that a bit of shaving on the C/Y mount would get it on the K mount - be it without being able to lock it in.

So, that begs the question - how good are the images?

thomasxie · 07-26-2011, 08:41 PM

Hi, I did not mean to offend anybody by doing a small surgery on the lens. In fact, I will buy the "expensive" adapter if I am shooting with Pentax all the time. I am just exploring the possibilities.

RioRico · 07-26-2011, 09:11 PM

Originally posted by thomasxie

Hi, I did not mean to offend anybody by doing a small surgery on the lens. In fact, I will buy the "expensive" adapter if I am shooting with Pentax all the time. I am just exploring the possibilities.

I doubt many here are offended. Yes, I have adapted inexpensive C/Y lenses for Pentax. No screw removal needed -- I just used a Dremel tool to taper the lens bayonet flags slightly so they fit under Pentax mount lugs. I also cut a small slot in the lens base for the Pentax locking pin to engage, for a secure fit. This is 'minor' surgery that still allows the lenses to be used on C/Y mount cameras.

The Leitax lens-base-replacement is rather expensive. A decision on whether to choose Leitax, or to perform this minor surgery, probably depends on value and expectation. How much is the lens worth? Do I expect to ever sell it? Do I want a slightly-cut lens that will fit both PK and C/Y mounts, or a professionally-done job that can ONLY be used on Pentax? I can't make that decision for other people.

The C/Y base is very similar to OM, and the OM surgery is the same as for C/Y, except that I need to tape-down the lens' stop-down button. A bit of metal duct-repair tape works just fine; it is the same tape I apply to manual lens bases to enable Catch-In-Focus. Modifying Nikon AI-mount lenses is more invasive; I cut off the "nub-and-arc" protrusions from the aperture ring, so the lens cannot be used on Nikon cameras again. But with cheap lenses, I don't care!

My first C/Y mod was a planar Yashica ML 50/1.4. I am very happy with it. Have fun with your great lens on Pentax!

07-26-2011, 06:38 AM	#1
thomasxie Senior Member Join Date: Dec 2008 Location: MN, US Posts: 139	Using Zeiss 50mm 1.4 C/Y mount on Pentax w/o adapter I have been using my Zeiss T* 50mm 1.4 C/Y mount on Canon EOS with adapter for a while. However, I always want to try it on my wife's pentax cameras without pay the "expensive" conversion kit. Here is what I did to use it on pentax. Two out of the 3 silver color metal pieces as show in the 2nd and 3rd pictures were shaved for a little bit. I put some tapes under the silver color mount ring (unscrew the 3 screws) to rise it up. Now I can fit the lens on the K20D! You need to be careful since the lens is not locked on the body. Attached Images

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07-26-2011, 07:47 AM	#2
interested_observer Loyal Site Supporter Join Date: Jun 2009 Location: Tumbleweed, Arizona Photos: Gallery \| Albums Posts: 5,707	Good Morning, I certainly understand about wanting to use your lens on both the Canon and the Pentax bodies. From what I understand its an outstanding lens. There is a slight difference in the registration distance between the C/Y and K mounts - just enough that there is really no way to have an adapter fit one on to the lens and be able to mount it successfully on the Pentax camera. The two mounts are extremely close to each other, which in a way is understandable since Zeiss either helped (K) or fully designed (C/Y) both of them in essentially the same timeframe. On the other hand, there is a rather large difference between the registration distance between the Canon and C/Y mounts, which makes an adapter possible on a Canon body. I only wanted to use my Contax lens on the Pentax body, so I went the "expensive" mount replacement route. I do not know that Leitax is making a small fortune on making and selling them. There appears to be a lot of machining in terms of making the mount and the tolerances appear to be relatively tight. The material is not cheap - its a good grade of stainless steel. Rico here on the board has indicated a couple of times, that a bit of shaving on the C/Y mount would get it on the K mount - be it without being able to lock it in. So, that begs the question - how good are the images?

07-26-2011, 08:41 PM	#3
thomasxie Senior Member Join Date: Dec 2008 Location: MN, US Posts: 139 Original Poster	Hi, I did not mean to offend anybody by doing a small surgery on the lens. In fact, I will buy the "expensive" adapter if I am shooting with Pentax all the time. I am just exploring the possibilities.

07-26-2011, 09:11 PM	#4
RioRico Veteran Member Join Date: Jun 2008 Location: Limbo, California Posts: 11,263	Originally posted by thomasxie Hi, I did not mean to offend anybody by doing a small surgery on the lens. In fact, I will buy the "expensive" adapter if I am shooting with Pentax all the time. I am just exploring the possibilities. I doubt many here are offended. Yes, I have adapted inexpensive C/Y lenses for Pentax. No screw removal needed -- I just used a Dremel tool to taper the lens bayonet flags slightly so they fit under Pentax mount lugs. I also cut a small slot in the lens base for the Pentax locking pin to engage, for a secure fit. This is 'minor' surgery that still allows the lenses to be used on C/Y mount cameras. The Leitax lens-base-replacement is rather expensive. A decision on whether to choose Leitax, or to perform this minor surgery, probably depends on value and expectation. How much is the lens worth? Do I expect to ever sell it? Do I want a slightly-cut lens that will fit both PK and C/Y mounts, or a professionally-done job that can ONLY be used on Pentax? I can't make that decision for other people. The C/Y base is very similar to OM, and the OM surgery is the same as for C/Y, except that I need to tape-down the lens' stop-down button. A bit of metal duct-repair tape works just fine; it is the same tape I apply to manual lens bases to enable Catch-In-Focus. Modifying Nikon AI-mount lenses is more invasive; I cut off the "nub-and-arc" protrusions from the aperture ring, so the lens cannot be used on Nikon cameras again. But with cheap lenses, I don't care! My first C/Y mod was a planar Yashica ML 50/1.4. I am very happy with it. Have fun with your great lens on Pentax!