Originally posted by zburatoru I have a lot of experience with manual focusing but to shoot 5 frames to get a decent sharpness it's a little too much!
Do you have experience with manual focusing a very fast telephoto lens? E.g. 85mm or longer with an f/1.4 or wider aperture? If not, this is why you are having difficulty focusing this lens accurately. Especially with very close up subjects, the depth of field is
tiny.
Originally posted by zburatoru How it's focusing? The image has strong green CA in the center at first focus beep and if you continuing to focus it's disappears?
As I suggested earlier in the thread, focus confirmation on DSLR cameras isn't 100% accurate. It will beep and you'll see the focus confirmation indicator when you get
close to being in focus, but not at the precise point where it is exactly in focus... and it will remain active across a small focusing range either side of the correct focus setting. Given the tiny depth of field we're talking about here, you simply can't rely on focus confirmation for accurate focusing.
Only areas of the subject that are in *perfect* focus will be free of glow and/or blur. Anything in front of or behind the exact focus distance, especially at fast apertures, will have some glow and/or blur. And if you move back or forth even the slightest amount while taking your shot, the point of accurate focus can change enough to throw the subject you thought you were focused on out of focus.
If you then add an extension ring for close focusing (as I believe you mentioned in an earlier post), the depth of field will become even narrower, and focusing even more critical. The glow, aberrations etc. will be even more noticeable.
Everything I've mentioned above is the same for *any* fast, telephoto, manual focusing lens, used on any DSLR camera that offers focus confirmation.