simplejoy wrote: ↑Wed Feb 15, 2023 2:36 pm
jvanhuys wrote: ↑Tue Feb 14, 2023 8:50 pm
Also, not sure if these are your images, but I found some sample pics taken with the Dokumar 47 f/5.6, which are unbelievably, sharp, but then this one image suffered from quite a bit of CA. Was this because it's a blade of grass, and thus, so much closer than the Dokumar's magnification range of 1:75 to 1:30? You were probably down to 1:1 on this shot right?
https://flic.kr/p/2mgGwJm
Glad you find the Dokumars interesting - however a word of caution: Even if they were among the most impressive lenses for certain magnifications when they were created, I doubt that many of the samples still around are up for the challenge. Don't get me wrong - I like my Dokumar 47 mm f/5.6 and I'm completely aware of the fact that the main point for not being fully convinced about its qualities might be caused by me using it outside of its sweet spot, but I just never felt like it was among the best lenses for anything. I'm not a very artistic person, so I don't have any real artwork to show, but I took a quick shot of one of my recent attempts at motivating my child to color something with wax crayons:
Dokumar 47 mm (Stack of 6 images, unedited)
The size of the paper is 420x297 mm.
And here is an image showing the CA correction of the lens on a more challenging subject:
Dokumar 47 mm (single shot, SOOC) I'd say it's quite okay actually, but there are better lenses in this aspect as well. The S-Planar 120 mm I just compared it with as well did significantly worse though, so if there are a lot of elements in your artwork which might lead to CA problems, I'd call this a significant flaw.
Lou Jost wrote: ↑Wed Feb 15, 2023 7:16 am
Just want to re-emphasize that field flatness doesn't matter much if you stack. Robert's tests often show this, as he often has to use different frames for his center and corner best shots, but these stack seamlessly.
I don't have a lot of experience with things like that, but I'd agree that stacking works pretty well in those cases.
Hey!
I can't tell you how valuable this is for me. Thank you so much.
It seems this lens is possibly showing its age due to worn out coatings or probably single-coating? Upping the contrast within reasonable levels seems to have a negligible filter hit compared to matrix operations like convolves, blurs, distortion/CA correction. Those things for my work, soften the image too much. When I increase the contrast by 25% on my Symmar-S 180 (single-coated) it is as good as my Micro Nikkor 105 in the centre... and it definitely beats the Nikkor in the corners with significantly better CA control and a touch less barrel distortion (possibly none?). On top of that I have the movements to do my stitches.
I'm trying to say, the lack of micro-contrast in the Dokumar doesn't worry me. My mortal enemies for flat artwork are distortion and CA. Even sharpness is lower priority. I noticed that the extreme shadows and highlights in ferrule of the brush, are very well handled by the Dokumar. That's a distance I would shoot too. The CA seems almost nullified at that . This is very promising. My Micro Nikkor 105, for example, is unusable with those extreme values due to CA. If we were looking at a 32-bit exr outside of Photoshop, in say, Nuke with a camera capable of ACES colorspace capture, with that contrast ratio, that same highlight's value would be between 30 and 50 and the shadow would be close to 0. So, again, I'm impressed.
I hear what you're saying about it being good for it's time but modern lenses being better. I get that it's not quite as sharp as the S-Biogon 40mm, or the Nikkor 55 Micro in terms of lines per millimeter, but I'm noting multiple things that I love. I looked at some very high resolution images of the S-Biogon on Flickr, and despite its remarkable sharpness, I noted that it has fairly bad distortion, of the pincussion-type. I had the Nikokr 55 for years, which is famously sharp too, but I sold it because it had too much barrel-distortion for flat artwork. The CA control was not bad, but nothing near a true Apochromat.
I think I'm gonna pull the trigger on the Dokumar and post some results once it arrives a few weeks from now. Thank you so much for spending time on this. Let me know if you ever want me to run a test setup for something you're curious about.