Digitally adapting Yashica AF lenses

I tried a few chemical methods to modify the blue anodized coating and get it to blacken without success. I've used a cold-process product in the past called Aluminum Black (by Birchwood Casey), and it's never failed to turn anything to a deep flat black in under 15-30 minutes. After reading a few posts on modifying anodized finishes, there's nothing that will affect the color it is without first removing the anodizing that's already there. Of all the removal methods I've found for home DIY jobs, warns that everything is nasty to use and caustic stuff, so I'll ask a friend who's a machinist for his advice once he's back from vacation. I did have some flocking material to cut a strip and cover the inner barrel area to get rid of its reflections, so that I could run some basic lens tests at least.

Since lenslover asked about the 28-85mm comparison specifically, I thought it was as good a candidate to start on as any, so I set up a quick 'back porch' test with the help of a few props that might seem familiar. The plane of focus is roughly the same for everything shown in the prop setup, but the treasury seal was used as the 'official' focus point, and the eyes of the china doll were meant to be the focus on the 3D object. These aren't glamorous photos by any stretch, and forgive the obvious spots on my sensor that shows up fairly well by f/11 or smaller. I tried to make the comparison as neutral as possible, so here's the setup and parameters I used...

Shot on a Manfrotto 3021BPRO tripod at ISO 100, with aperture priority on a Sony A7R, with the meter set on matrix and with no EV adjustments. White balance was custom set with an XRite ColorChecker Passport WB patch, and an initial shot was taken of the color chart immediately after that, with the ML 28-85mm. It's also the first lens used in each regular shot set, followed by the AF. I set the camera as near as I could get it to the minimum focus distance allowed by the ML, since the AF has a bit shorter distance for its minimum. I used 3 focal settings to shoot with, at 85, 50, then 28 - and then swapped lenses for each one... so the progression is, 85mm ML, 85mm AF, then 50mm ML, 50mm AF, etc.

F-stops are not exactly comparable between them with the way the FotoDiox AF adapter works, and the NovoFlex used on the ML has no aperture settings - so - first shots on both lenses are wide open, then for the ML I went from 3.5 to 5.6 (not the '4-ish' quasi-stop), then 8/11/16/22, with the AF going click-by-click down to the third from the last stop. The last 2 stops made no aperture changes at all. I wasn't paying much attention at the time on how well matched the shutter speeds would have been, but the testbed will show the EXIF values if you click the little 'i' icon on each image page.

The last series of shots are using the macro function available on both lenses - and again - with each at its approximate minimum focus distance. This time I used the AF set much closer than the ML since there's a fair amount of difference between them. One note on the focal length set here, is that the AF must be put into macro mode at 85mm only. The ML will sip into macro at any focal length, so I set it to match the 85mm as well. This series has the AF as the first lens, followed by the ML.

After I imported all the RAW files onto a hard drive, I used LightRoom 5 to create a color profile from the initial ColorChecker chart. I applied that same profile to every RAW image to then convert and export them in a batch. Each one is a 1600px wide jpeg file, with no additional processing and with an output quality setting of 60%. That gave me reasonably small files (roughly 130-240Kb each) to post to my Testbed Gallery to share the whole batch without posting the full size XXMb sized files. I used my stubby little pinkies as indicators of what lens I was switching to for each pass. 1 for the ML, and 2 for the AF, with the Passport as shot #1.

The reason for the WB and ColorChecker setup was to allow for a consistent known-good profile across both sets of image, without letting the Sony's automatic functions take over and try to make everything match its internal algorithms. I think it will be pretty obvious there's a color rendering difference between them, so ignore my fingers in that case. These are underexposed by maybe 1/2 a stop as a result - but I think you can still compare them, even when a bit darker than I'd normally shoot them.

I won't post my own conclusions right at the moment, but there were some surprises in doing these tests... and I think I'll be following @biggles advice from the other thread, in trying to find some more primes.

Two quick samples at 85mm and both wide open, with the ML first, followed by the AF...





And if anyone has a recommendation of someone great for sensor cleaning in the US, I think I'll need the first pass on this one done by a pro. :)

"The bottom line... The more I look at the test shots, the more I think I need to redo them all, and try to diagnose what issues I may have introduced myself. We're back in a cold-snap again at 41° F, so once the weather cooperates, I'll re-shoot the whole test."

Thanks much for the kind, honest words. A rare post, these days. Much appreciated. Yes, i do think the same, if you do have some spare time into the upcoming weeks.
The 28-85 ML itself is a great lens, not really much lagging behind it's MM-Type Zeiss Counterpart, and i am confused with these yellow cast, dull, flat looking pictures from the ML. Maybe the Lens Elements got misaligned, very subtle with the CLA Task? Or some sort of A7R WB Settings...i don't know. I've never seen images like this, from that ML Zoom, like you.

A fine Sunday.

I think the only way to conduct that test is to mount the lenses on their respective OEM bodies, because those adapters are going to introduce variables, particularly because they are by different manufacturers (quality control is one factor). If the adapters were by the same company your results might be closer.

PF

The K&F adapters do seem to be the better brand from all the various ones I've used (and I think I've tried most, if not all of them), but I'd hesitate to say the same about the Beschoi brand.

To me, it seems pretty obvious that the casting and the overall 'look' is pretty much identical - but - that's only what you see, and not, how it performs. I won't assume these 2 brands were made in the same facility, or that they were assembled by a different company using purchased K&F parts.

Granted, I only have the one Beschoi adapter and it could be a bad sample, but my particular one should never have left the factory of whomever made and/or assembled it. It might be that the assembly person doing the mount ring was overzealous on tightening screws, or it could be that the underlying body casing was milled badly under the mount. It might even be a case of K&F scrap that was out of tolerance (even by Chinese standards) and slated to be ground up and melted for recasting, suddenly found its way into another assembly plant 'by mistake'. This is pure speculation on what happened, but the results are awful, and the mount ring is visually wavy when inspected.

Any lens going onto it requires extra effort, and it can sometimes feel and sound like sand grinding gravel, and this was it's last appearance before heading to the trash. I won't speculate on what the issues are, so I'll let the pictures tell the story instead.