Zeiss Distagon T* 21MM F2.8 ZM

[dseelig]

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The 25 also has to have the mount changed get the zeiss 35 from zeiss send it to john milch for putting in the receeses and then send the 25 to don goldberg to remove the mount and put on the 35 mount. . Keep you old mount off the 25 if you ever want the zeiss 21 you will have the mount already. Not I am keeping my zeiss 25 and selling the 21 zeiss only because withthe wate I have the 21 covered. David

[dseelig]

Both zeiss 21 mm bring up the 50 framelines. You need to order a 28 mount frm zeiss

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[ccc yyy]

You need to order a 28 mount frm zeiss

 

so why does the mount matter if

there are no 21mm frame lines??

[dseelig]

If you want to have the M8 trigger the correct frame lines the 28 mount 6 bit coded to enable the M8 vignetting to be correct for the 21 lens David

[ccc yyy]

If you want to have the M8 trigger the correct frame lines the 28 mount 6 bit coded to enable the M8 vignetting to be correct for the 21 lens David

 

i'm not sure i understand why the 28 frame lines

are the correct frame lines for a 21mm lens. ??

(considering that the existing frame lines are

already crop-factor adjusted.)

 

regarding vignetting, i would think you'd want to

code the lens as one of Leica's 21s and not a 28.

[mtwo]

OK, so add me to the ranks of the confused. I have the Zeiss 21/f2.8 Biogon. It is a lovely piece of glass but I have used it sparingly. First I need to remove the eyepiece magnifier and then have to squash my eye to the vf to see the entire frame. I would like to have it bring up the proper frame lines and inquired of John Milch what to do. He said to remove the mounting flange and send it in and for 25 or 28 bucks he would mill it. His e-mail was cryptic to be kind about it. Does Milch mill the flange to bring up the proper frame lines or do it get it back with some little indents to put black stuff in? And then, when coding it should the codes for a 28 be used or a 21 Leitz? I may just have to break down and read reid and pay the bucks it entails. I am not buying any more lenses but coding the mix I now have is something of a priority. Comes right after getting out to shoot fall foliage and whatever else my come my way. Shedding more light for us confused types would be helpful. Point me somewhere. I can still read even if confusion comes easily. John

[voightL]

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i'm not sure i understand why the 28 frame lines

are the correct frame lines for a 21mm lens. ??

(considering that the existing frame lines are

already crop-factor adjusted.)

 

regarding vignetting, i would think you'd want to

code the lens as one of Leica's 21s and not a 28.

 

Hi Roman,

You may also want to look at this thread:

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/31640-21mm-biogon-m8.html

[voightL]

OK, so add me to the ranks of the confused. I have the Zeiss 21/f2.8 Biogon. It is a lovely piece of glass but I have used it sparingly. First I need to remove the eyepiece magnifier and then have to squash my eye to the vf to see the entire frame. I would like to have it bring up the proper frame lines and inquired of John Milch what to do. He said to remove the mounting flange and send it in and for 25 or 28 bucks he would mill it. His e-mail was cryptic to be kind about it. Does Milch mill the flange to bring up the proper frame lines or do it get it back with some little indents to put black stuff in? And then, when coding it should the codes for a 28 be used or a 21 Leitz? I may just have to break down and read reid and pay the bucks it entails. I am not buying any more lenses but coding the mix I now have is something of a priority. Comes right after getting out to shoot fall foliage and whatever else my come my way. Shedding more light for us confused types would be helpful. Point me somewhere. I can still read even if confusion comes easily. John

 

I think the ZM21mm brings up the 50/75 framelines. You need to change the lens mount to a ZM28mm lens mount to bring up 28/90 framelines like the Elmarit21mm. You can order it through Zeiss in Germany-I have listed the contact in an earlier post in this thread.

John Milich will mill recesses(holes) to enable you to code the lens but send the ZM28mm lens mount to JM, not the original mount that comes with the ZM21mm. Then code it like Elmarit21mm.

It seems you need to have the correct code as well as the same framelines as the Elmarit21mm for the in camera software to correct everything properly.

I hope I did not add to your confusion.

My ZM21mm is on order but the ZM28mm mount I have received from Zeiss Germany is on its way to JM for milling:)

 

Go to this thread as they discuss most of the issues with ZM21mm

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/31640-21mm-biogon-m8.html

[Dan States]

The 28mm frames in the M8 have an angle of view roughly equivalent to a 35mm lens in film format. There are no frames wide enough in a standard M8 viewfinder to accurately represent the field of view for the 21mm lens. I use the outer black edges of the viewfinderr as a guide and that seems accurate enough for me. If you want more accuracy get a Voigtlander 28mm finder and clip it on top, as the 21 on the M8 has about the same angle of view as a 28mm lens on film.

[dseelig]

Have a real pro like don goldberg change the mounts. someone who can check focus . David

[ccc yyy]

It seems you need to have the correct code as well as the same framelines as the Elmarit21mm for the in camera software to correct everything properly.

 

can this coding thing get any more

convoluted than this. ??

thanks for the clarification.

[sean_reid]

This is all discussed in my 21 mm lens review.

 

Cheers,

 

Sean

[cme4brain]

can this coding thing get any more

convoluted than this. ??

thanks for the clarification.

 

It is not that confusing, once you take medication. The correct brightness and cyan-drift vignetting computer algorithm used in the M8 depends on the particular lens, and how the M8 know what lens you have mounted depends on TWO things- the lens mount and the six bit black and white coding bits. Remember that Leica is forcing the M8 to be compatible with 50+ year old lenses, and the correct brightline frame in the viewfinder (from the M3 to the M7 and M8) is triggered by the lens mount. No matter what M camea you use (meaning the viewfinder magnification- from 0.68 in the M8 or 0.72 in most M6/7's or 0.85 in others), the framelines displayed show you the approximate FOV of the lens you have mounted. You mount a lens, the M film camera automatically shows the correct PAIR of framelines- like both the 28 and 90mm line pair. This feature was a big selling point for Leica and a tremendous advantage. But remember that now the M8 is digital and has a crop factor of 1.33- so now your 21mm lens, when used on a film M, no longer shows a FOV of 21mm, it shows a FOV of 28mm. Now the M8 viewfinder's magnification has to display an effective FOV of a 28mm lens (as if it is a film lens). This is done for us, but remember that the backward compatibility of the M system requires that you now use a 28mm lens mount. Even though you have placed a 21mm lens on your M (and will get an effective FOV of a 28mm lens), the camera mechanical mount system (to be compatible with old lenses) is expecting to see a 28mm lens mount (because in the past the 28mm film lens was the widest the film M viewfinder would show- any wider and your rangefinder base length decreases and focusing accuracy does too).

 

Clear yet? Take more medication. So we are stuck with backwardly compatible film lens mounts (to trigger the proper viewfinder frameline pairs) and modern six-bit coding to trigger the vignetting correction problem. Also, using both systems allows Leica to have more lens codes (you must have THIS six bit code with THAT mechanical lens mount). So all in all, the M8 knows what lens you have placed on the camera by reading BOTH the lens mount and the six-bit code on the back of the lens.

 

Sean, please help me if I didn't explain this correctly.

[sean_reid]

Hi Lloyd,

 

That's mostly correct but a simpler explanation is that Leica uses the same bayonet pattern for 21, 28 and 90 mm lenses. All three trigger the same frame line sets. (The EFOV match on the M8 is a coincidence.) So when a 21 is mounted on an M7, it still triggers the 28/90 frame lines (which doesn't matter because an external finder is needed for that lens on a film camera).

 

As you know, I've discussed all of this, in some depth, on the site but the bayonet types are:

 

21/28/90 (this includes the WATE)

24/35/135

50/75

 

There are, of course, only three bayonet patterns and this is why, for example, John Milich makes only three versions of the LT-M8 adapter.

 

Cheers,

 

Sean

[gurtch]

I use ZM 21mm, 28mm, 35mm and 50mm lenses. I think they are great! I did not change any bayonet mounts etc, because with the 21mm lens I use an external CV 28mm finder. Works great. Here are 4 shots done on spec for a local yacht club using the 21 and 28 ZMs.

Dave G., Beach Haven, NJ

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[ccc yyy]

cme4brain, i would suggest you lay off the meds bud.

not confused. actually mostly clear on how convoluted this is.

 

 

if the only purpose of the bayonet mount is to trigger the appropriate

frame lines, then any bayonet mount should suffice since there are

no 21mm frame lines on any of Leica bodies. and for proper framing

of a 21mm lens one resorts to an external viewfinder: a 21mm VF

for a film body and a 28mm VF for the m8.

 

so now we're back to the coding itself.

in theory one would think that all that would be required to have the

in-camera software adjust for vignetting (and anything else the s/w

adjusts for a given FL or FL-equiv) are proper 6bit code markings on

the bayonet mount (... any bayonet mount that is).

though based on what i've learned through this thread, it sounds like

the m8 requires not only the proper coding (which i follow) but also a

presence of a 28 bayonet mount (which i still don't) to enable the s/w

algorithm to do its stuff (... if i understood correctly).

as coding, corresponding to the correct 21mm FL selection, applied

to either of the other two bayonet mount types will not engage the

in-camera s/w for "proper" adjustment/s to the captured image.

[jaapv]

It's all here, in this old,old thread...

 

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/20663-zeica-21-2-8-a.html

[teehas53]

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

[ccc yyy]

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.

 

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

inform the m8 which lens is mounted?

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[teehas53]

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

inform the m8 which lens is mounted?

 

You'd have to ask an engineer at Leica about that. Or maybe someone else here can explain why. Something to do with backwards-compatibility with all pre-existing Leica 21s I imagine. It's moot, however, as this is the way the camera works, regardless of whether it may or may not make sense.

 

The bottom line is, if you want to use a Zeiss 21 on the M8 with firmware correction, you need to change the mount and code it. It's not that big a deal, and the lens is definitely good enough to be worth the effort. Or, you could pony up for a 6-bit 21mm Elamrit Asph and forget all this...

 

T