Zeiss 21/4.5 C Biogon on M8

[southerncross6]

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Hello, everyone

 

I have just bought a Zeiss C Biogon 21/4.5 lens. Now I face the dilemma of dealing with the cyan corners.

 

From this forum and general googling, I have collected the options. I could use cornerfix. But if I want automatic correction, I need to code the lens.

 

My questions are:

 

1. What code to use for ZM 21/4.5? Wide Angle Tri-Elmar or Elmarit 21/2.8?

 

2. Do I have to change the lens mount. The ZM lens have the 50/75 mount. Do I have to change it to 28/90 for the coding to work? And where can I get the mount changed?

 

3. Is it worth the trouble? From the what I have read, after I code it the lens, cyan corners disappaer but exposure vignetting increases. Is it right? Personally I do not like to much lens vignetting. I sold my Leitz 21 Super Angulon for this reason. If I still have to correct vignetting in PS or LR afterwards, I'd rather have cornerfix do it all for me.

 

I appreciate for any help

 

Estel

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[scott kirkpatrick]

Hello, everyone

 

I have just bought a Zeiss C Biogon 21/4.5 lens. Now I face the dilemma of dealing with the cyan corners.

 

From this forum and general googling, I have collected the options. I could use cornerfix. But if I want automatic correction, I need to code the lens.

 

My questions are:

 

1. What code to use for ZM 21/4.5? Wide Angle Tri-Elmar or Elmarit 21/2.8?

 

2. Do I have to change the lens mount. The ZM lens have the 50/75 mount. Do I have to change it to 28/90 for the coding to work? And where can I get the mount changed?

 

3. Is it worth the trouble? From the what I have read, after I code it the lens, cyan corners disappaer but exposure vignetting increases. Is it right? Personally I do not like to much lens vignetting. I sold my Leitz 21 Super Angulon for this reason. If I still have to correct vignetting in PS or LR afterwards, I'd rather have cornerfix do it all for me.

 

I appreciate for any help

 

Estel

 

1) The Elmarit 231/2.8 is probably closer in its luminance vignetting characteristics than the WATE, since the WATE is a longer, more telecentric lens. In red-vignetting, with a UV/IR interference filter in front, the focal length is the most important factor, so the two lenses should have a similar correction (but nobody has done the obvious experiment to find out what the firmware actually does yet).

 

2) I think you have to change the mount to have it recognized as a 21. Leica lenses bring up the 28/90 mm frame lines, and the firmware includes a test for this. Since you have to remove the bayonet mount to have it milled for permanent coding, going to Zeiss for the proper mount is not much extra trouble.

 

3) The present status is (but this may well change) that if you ask for "lens detection ON" and have a coded lens you get a strong correction for luminance vignetting. However, if you set "lens detection ON+UV/IR" when you have a filter in place, you will get much weaker luminance vignetting correction (but still some) and fairly accurate red vignetting correction. For either option to work, you need to create a bar code and either hold the frame lever in at the 28/90 position or change the mount.

 

scott