Mechanics: This is a very late model Carl Zeiss Jena 85mm f/2 Sonnar T lens, which uses some of the last Carl Zeiss Jena T coated optics while also clearly displaying the pre-Opton mechanical body design. Very much a transition era lens, probably made originally in Coburg, Germany.
Lens was stripped down, ultrasonically cleaned, and rebuilt from the ground up. During the process, the external aluminum parts were sent to Camerakote of Staffordshire, England for a very unique finish.
Experimental Alu-Patina Finish:
We had always wondered what an all brassed gloss black 85mm sonnar would look like, but the later Jena and Opton mechanics use aluminum outer parts. Camerakote applied a special finish for this lens, where it has an undercoat of Golden Brass Cerakote, a very hard wearing ceramic base layer. Camerakote then had the lens painted using an experimental paint developed by Stuart Semple of Culture Hustle, which is a Black Mirror BETA paint. We had to test the lens a bit to ensure what we were envisioning would work…
Needless to say, this is the first aluminum based lens, that will patina and brass with age over time! Very gradual brassing has begun to take place mostly on the focus knurling thus far. The key is that the Black Mirror BETA paint will wear down like Black Lacquer which is used on Black Gloss Leica Cameras and lenses (Kravitz style). As the paint wears down, it exposes the under brass cerakote layer. The brass cerakote layer, being ceramic, will not wear down. Thus this lens will age and patina with usage over time, but the user is graced with the lighter aluminum body providing a substantial weight savings over the all brass versions (which are also only uncoated optics).
A modified CRF to LM adapter, which has been married calibration-wise to the main lens, also completes the conversion.
Lens triggers the 50/ 75mm frame lines. We find the 75mm works better for the 85mm focal length, than the 90mm frame lines. The 75mm frame lines are closer to the true focal length field of view in various tests we have done.
Optically, as with many of our fully converted lenses, we have re-centred the optics inside the lens, ensuring their spacing and rotation evenly distributes the aberrations, while also achieving the sharpest combination. The lens is perfectly calibrated to the RF cam, for f/2 aperture usage.
The lens does have some fine coating marks, some external cleaning marks and there are a few internal cleaning marks. No haze, no funugs.
85mm Sonnars wise, this is a sharp copy, with beautiful bokeh and colour rendering as can be seen in the last photo.
Lens comes with a custom push-on metal 49mm cap and a rear M cap.
Due note, this lens is supposed to patina/ brass with usage over time, we’ve gone out of our way to make what was previously impossible, now possible, for a discerning patina-loving rangefinder user.