About Coding Lenses for the M8 and M9

[JPSuisse]

Hi all

So, I've been the user of several wide angle lenses from Leica including:

Summilux-M 50mm ASPH, coded
Summicron-M 35mm ASPH, coded
Summicron-M 28mm ASPH, coded

About a year ago I decided to purchase Biogon ZM T* 21mm, and the question that I have not yet been able to answer is, should I code the lens or not?

I was surprised when I forgot the IR filters on my lenses on my film cameras. I found that the Summicron-M 28mm causes worse color vignetting in the corners than the Biogon ZM T* 21mm with filter. I would have thought the opposite would have been true. The point is, that I suspect now that the vignetting is a function of lens design and not focal length.

Anyway, since the coding is for Leica lenses, if I code the Biogon as say some 21mm Leica lens, who can say, if this really corresponds to the needs of the Biogon? Afterall, the curvature of the back element will not be the same and thus the way the light hits the sensor form oblique angles will also not be the same for all 21mm lenses. Or has somebody tested the available codes and decided which Leica coding actually works best with the Biogon?

What is the educating opinon about this issue amongst our fellow Rangefinder Forum users'?

JP

 

[jaapv]

The Biogon 21 works best if it is coded as a Elmarit 21asph. However it depends if you can do that on the mount fitted. It needs to have the 28 mm mount.

 

[JPSuisse]

Hi Jaap

Thanks for the reply. But I don't 100% understand your answer.

1.) Do you mean the mount that brings up the 28mm frame lines? If so, this is the verison I have. I'm in luck.

2.) Given your answer, it sounds like my suspicion is correct. People just tried different codings for wide angle lenses on the Biogon ZM T* 21mm and took the coding that gave the best reuslts. This just happens to be the coding for the 21mm ASPH. Hence, a custom profiling of the lens by Leica and included in the M8's firmware really would give the best results. But, alas, this will never happen...

Cheers, JP