Question about Zeiss M-mount and Framelines

[photolandscape]

Advertisement (gone after registration)

I bought a Zeiss 25mm Biogon recently, and the seller says it has the retrofitted M-mount to bring up the*24mm framelines. When I put the lens on my M9, I get the 28mm framelines instead of the 24mm. What is different about the retrofitted Zeiss M-mount on the 25mm lens that brings up the correct 24mm frameline? There must be some mechanical feature on the mount, but I can't figure out what it is.

 

Thanks.

[thrice]

There are no 24mm framelines on the M9. The M8/8.2 have 24mm framelines shown along with the 35mm framelines, but no 135mm framelines.

 

The lens will bring up the 35/135 framelines on your M9 if it has been modified, so you can code it as a 24mm Elmarit. If the lens is bringing up 28/90 framelines it likely hasn't been modified, simply code it as a 28 Summicron ASPH which gives a good result as well.

 

You will still need the accessory viewfinder for 'accurate' framing.

[ho_co]

... There must be some mechanical feature on the mount, but I can't figure out what it is....

Steve--

Beginning with the M3, one of the flanges on the back of the lens mount has a varying length based on focal length.

 

If you've got several lenses, set them up side by side, bayonet end up, and compare the lengths of all four flanges on all lenses. The one that ends up next to the frame preview lever on the camera has one of three lengths; the others are the same for all lenses.

 

As you know, when you mount an M lens, the lens moves the frame preview lever to its proper location. Since there are three positions for the lever, there are three lengths for the flange. If you look at the part of the body bayonet opening which is beside the frame preview lever, you'll see the lever involved.

 

I hope that helps.

[wlaidlaw]

I bought a Zeiss 25mm Biogon recently, and the seller says it has the retrofitted M-mount to bring up the*24mm framelines. When I put the lens on my M9, I get the 28mm framelines instead of the 24mm. What is different about the retrofitted Zeiss M-mount on the 25mm lens that brings up the correct 24mm frameline? There must be some mechanical feature on the mount, but I can't figure out what it is.

 

Thanks.

 

Zeiss' choice of M mounts on their ZM lenses always seems perverse to me. For example, they put the 24/35/135 mount on the 21 Biogon, so that to get it to work hand coded on an M8, you have to change it to a 28/90 mount. Selling the 25mm Biogon with a 28/90 mount on it seems to make no sense whatsoever. Supposedly you can order the lenses with whatever mount you want but I don't know anyone who has achieved this.

 

Wilson

[thrice]

My 25mm Biogon came from Popflash with the 35/135 bayonet flange, in fact they have many ZM lenses brand new which they have gotten with the 'convenient' flange installed direct from the factory. They are well in tune to the community, they also have 1.5 optimised 50mm C-Sonnar's for example.

[wlaidlaw]

My 25mm Biogon came from Popflash with the 35/135 bayonet flange, in fact they have many ZM lenses brand new which they have gotten with the 'convenient' flange installed direct from the factory. They are well in tune to the community, they also have 1.5 optimised 50mm C-Sonnar's for example.

 

Daniel,

 

The dealers in the US have obviously got their relationship with Zeiss/Cosina better sorted than the dealers in the UK. When I was looking at getting a Biogon 25 some months ago, I was quoted 12 to 16 weeks delivery for a 35 mount version.

 

Wilson