candreyo
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 p.5 #6 · Front-End Filter Improves Corner Smearing | |
Greetings,
I've registered with this forum just so I could post on this thread!
I'm an opto-mechanical design engineer who works with Lasers, and a passionate photography enthusiast on the side.
I have almost a full set of Zeiss ZM lenses, and am willing to take a stab at this to try and see if I can program some of the Zeiss ZM lenses, and find which PCX lenses may work the best.
I have a 1500mm PCX lens being mailed to me from Laser 2000 (UK distributor for Optosigma).
My main goal is the Zeiss 25mm and 28mm lenses, as these perform the worst for me on the Sony A7 cameras.
I have downloaded the OSLO software, and have gotten a copy of the Zeiss Contax G datasheets. I've been trying to wade my way through it, and decided to try and simulate the 28mm Biogon G lens in the software, so I get a hang on how it works.
Unfortunately, after following Haruhiko T's wonderful guide here and using the values from Zeiss's website, I still haven't been able to get the Contax G 28mm to compute correctly.
I would like to use this Contax G 28mm lens as a baseline for me developing a Zeiss 28mm ZM lens simulation. I understand they are different computations, but need to start somewhere.
Haruhiko T,
Would you mind sharing the exact contents of the *.len file you use to simulate the 28mm biogon here? That way I can see where I'm going wrong?
Equally, once my 1500mm PCX lens arrives, I'll let everyone know here how it fares on the Zeiss 25mm and 28mm ZM lenses. I also own a copy of the Zeiss 35mm 1.4 Distagon ZM lens, and shall place the 1500mm PCX on it to see how it fares also.
Hoping we can find a cure for the Zeiss ZM WA RF lenses also! This thread and its research have really perked my interest. 
Also, I may have a solution for the Zeiss ZM lenses when used on Sony A7, that may loose the ability to reach infinity with the PCX installed.
I have had about half my Zeiss ZM lenses disassembled in the past, adjusting their rangefinder focusing ability. The reason I did this was, many of them I bought used off ebay, and when I used them on my Leica M240, their focus was off (some too near, others too far). I have other Voigtlander and Leica lenses that have always worked fine with my M240, but have had problems with the Zeiss ZM range. Anyhow, often whats needed to simply correct the lenses so they focus properly, is installing or removing internal shims inside the lens. The shims are accessible my usually removing the rear lens retaining ring with a two pronged adjustable lens spanner.
The way Zeiss seems to adjust the lenses on their ZM line for accurate rangefinder focusing, is very similar to how the Soviet M39 Jupiter 3, 8, 11..etc. are adjusted. i.e., open the lens and add/ or remove shims. The Soviet Jupiter lenses themselves are post war clones of pre-war Zeiss lenses anyways, so it appears not much has changed in about 70+ years!
If by adding the PCX lenses to the Zeiss ZM WA lenses like the 25mm biogon, result in the lens not able to reach infinity anymore, its possible the lens could be adjusted internally with an appropriate shim to enable it to reach infinity.
This would definitely have a knock-on affect to the rangefinder focusing system, so if you plan to dual use these lenses with both a Leica body and a Sony body, this is probably bot the best option. However, for those that purely may use these lenses on a Sony body and don't care about the lens being accurate rangefinder wise, this might be a plausible solution?
Best Regards,
Candreyo
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