Carl Zeiss (West) 18mm f/4.0 Lens Optimized For Canon EOS 5D Camera
I got this great looking super wideangle Zeiss Distagon lens - but it´s back lens or more exact mechanics stopped the unshaved mirror of the EOS 5D. What to do?
Here you see the deep protruding part of the lens. A Canon EOS 5D accepts only ~1.5 mm protrusion behind normal Contax/Yashica - Canon EF adapters. There is no exact data - probably because the adapters may differ a bit in thickness.
Here one could see the marks from the mirror hitting the lens back end:
Shaving the camera mirror would be one idea - but the more you shave the mirror, the faster the the viewfinder image has missing parts - for example with long tele lenses or a macro setup. Both things I would like to avoid as much as possible. Because of this I decide to shave the lens mechanics as much as possible and the camera mirror as much as I need to get infinity.
I thought about working on the mechnics elements alone - with no lens in the near of it. This is much safer than filing on the complete lens assembly. But it seems not simple to get that ring and the protruding crank out of the lens - and back. And It would be hard to know how much I have to file away - probably several turns in disassembly and assembly of the lens.
So I take much care to use enough tape. And to have no slits or bigger bubbles in the tape.
I took a small file and worked carefully not to scratch the tape on the backlens. This tape gave a bit of protection and an early warning.
But still this lens does not work on a EOS 5D with normal mirror - I shaved the EOS 5D mirror a bit to accept this lens.
After the filing and testing I blackend the metall with a paint marker.
And I optimized the C/Y-EF adapter
a bit to minimize the tolerances of the adapter. For this I spread the slits around some 1/10mm.
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Here some test images made with this lens combination. You could see full EOS 5D image size. No CA correction made in post processing.
On some of the images I have used my home tinkered 8 mm extension tube.
This lens is a very rigid one - much better than the Samyang 14mm/f2.8.