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Zeiss Distagon T* 21MM F2.8 ZM


Patman

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this is the way the camera works, regardless of whether it may or may not make sense.

 

ok, as long as there is a good reason. ;):)

 

 

seriously though ... i understand the point you're making.

whether for engineering or more likely other reasons (e.g.,

"...you could pony up for a 6-bit 21mm Elamrit Asph..."),

as of today this is the only way to apply in-camera s/w

corrections to a non-OEM lens.

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Convoluted, for sure. The reason the mount needs to be changed to the 28mm version is that the M8 looks not only at the coding marks, but also at the frameline position (of the body, with lens mounted) to determine which lens is present.

 

So, to make an M8 "think" you have a 21mm Elmarit mounted, any other lens must also bring up 28mm framelines (since the Elmarit does this.) Then, with coding, the camera will apply firmware corrections as if the (non-Leica) lens is a 21mm Elmarit. Or whatever other Leica 21 you code it like.

 

By extension, if you were planning to use a thread-mount 21mm lens with an LTM8 adaptor, you'd order the 28/90mm LTM8.

 

The main reason for all this is to get the firmware correction, primarily for cyan drift when shooting in color. The vignetting issue is much easier to correct in post-production, although still extra work.

 

If you shoot color, I highly recommend coding, and a Leica-brand IR/UV filter for the 21mm focal length. The cyan drift is quite noticeable without it. If you shoot only (or mainly) B&W, then you may not need it. How much vignetting one is willing to accept or correct in post is an individual choice.

 

On the subject of Sean Reid's site (and the fact that he charges a modest fee to join,) it's by far the best bang-for-the-buck you'll ever spend on anything related to Leica, IMO. Before you spend another nickel on lenses especially, get on his site and read up! There's a wealth of information there, and his perspective is refreshingly real-world. Highly recommended!

 

And regarding John Milich, yes he is a man of few words;) But his products are top notch and the service is great. He has many satisfied customers on this forum.

 

T

 

 

Exactly what I said. You need the lens mount PLUS the six bit coding to tell the lens which exact lens you have mounted. Back to my medication.

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One thing I am confused on regarding the 21mm Biogon. I have read that this lens is not rangefinder coupled. What exactly does this mean? That the split image in the viewfinder does not work and you need to estimate the distance?

Thanks!

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Jim,

 

You are correct: lenses that are not rangefinder coupled do not activate the camera's rangefinder when focus is changed, and need to have focus set without aid of the rangefinder.

 

But I believe that the Zeiss 2.8 21mm lens IS rangefinder coupled. I have the C-Biogon 4.5 21mm, and it is coupled.

 

Steve

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Why does Zeiss make this so difficult for us?

 

Granted, they have their own film RF body that they surely want to put on the backs of their lenses, but why not offer their wonderful lenses ready to go onto M8s with 6-bit coding and the appropriate bayonet? Even if it were done on a special-order basis it might find a market.

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Why does Zeiss make this so difficult for us?

 

Granted, they have their own film RF body that they surely want to put on the backs of their lenses, but why not offer their wonderful lenses ready to go onto M8s with 6-bit coding and the appropriate bayonet? Even if it were done on a special-order basis it might find a market.

 

well they could make it really difficult and refuse to sell parts for their lenses to customers who are not repair technicians...:) on the whole I think zeiss was spectacularly helpful-I had the mount, no money paid in days from the email-

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Why does Zeiss make this so difficult for us?

 

Granted, they have their own film RF body that they surely want to put on the backs of their lenses, but why not offer their wonderful lenses ready to go onto M8s with 6-bit coding and the appropriate bayonet? Even if it were done on a special-order basis it might find a market.

How would they code it? Would their 28f2.8 be coded as an Elmarit or a Summicron?? It may be subjective / risky to assume what coding works with for correcting cyan drift accurately. If they did estimate, would it stay that way in future firmware upgrades. Thankfully we have a way to get them machined for us to experiment with.

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Zeiss will do it for a fee. Have you read my review of 21s on the M8?

 

Cheers,

 

Zeiss will exchange the flange for €60, but not if the flange has been coded already. It may therefore be debatable if this service from Zeiss is worth doing if you need to remove the flange to have it coded. A new flange costs €35.

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If the coding is protected by law (and I don't know whether it is), I'm sure Leica would sue a competitor who used it.

 

Leica have applied for a patent directed to the lens coding in several countries. I don't know whether any patent has been granted yet, but it is quite likely that these patents will be granted sooner or later. Which explains why Zeiss is not exactly keen on coding their lenses to match Leica's standard...

 

Andy

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so why wouldn't the coding by itself be sufficient enough to

inform the m8 which lens is mounted?

 

Because in that case the camera would not be able to tell the three focal lengths of the 28-35-50 Tri-Elmar apart.

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