Todd Adamson
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 p.3 #10 · My new Zeiss ZF 100 f/2 has focus issues | |
I just wanted to update this thread, because I feel somewhat vindicated to have found that the lens did indeed have a problem. Using the "flip" focus method recommended by Joakim, I did begin to be able to get some in-focus images, though I was still annoyed that the focus confirmation dot didn't work. However, even then my ability to get focus seemed inconsistent, and random. I was very frustrated, and was having a hard time believing it should be this way, since I can get focus with any other MF lens I tried.
Since then I have done a LOT of shooting with this lens and others. I borrowed a ZF.2 and did some extensive comparisons (different apertures, different subject-to-camera distances, etc, all on tripod with mirror lock-up and cable release), shooting various live and inanimate subjects as well as focus charts. I came to the firm conclusion that the ZF I had was messed up, both with regard to AF confirmation dot (which worked perfectly on the ZF.2 lens), and focus consistency.
As I was getting ready to return the ZF.2 lens, I was again comparing focus ring damping, because it had always seemed a little tight on the ZF, and I realized that when mounted, there was a significant difference in the amount of rotational (and even a bit of lateral) play between the two. The ZF had a LOT of play...maybe 5 degrees, I don't know, that's just a guess, but I don't know how I missed that before.
At any rate, green dot confirmation was off, and I suspect the inconsistency I saw was coming from a combination of the very hard damping, and the wiggly mount.
I have recently picked up another copy of the ZF version 100MP, and it's perfect. I'm getting a very high keeper rate, similar if not better than with my other MF lenses, just as I would expect. Even at f/2, no problems. More good news: in doing so much shooting with these and other MF lenses over the last couple of months, I have gotten very good at seeing focus in the D3's viewfinder, with stock focusing screen. I now have my focus points turned off, and never depend on the green dot. However, I did test it with this new copy, and it's very accurate.
In summary, the lens which caused me to start this thread was definitely hosed up. And I am very happy to have put this frustrating issue behind me. 
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