Reader Feedback on Making Sharp Images — Live View
Eric J writes:
In particular, my D3S and D3X image qualities were vastly improved
using the live view focus technique you described! Couple of questions here.(1) Does Live View preview in Nikon Camera Control Pro operate the same
way as you describe, i.e., the image is being displayed at the f-stop setting?(2) Have you reviewed or tested focusing issues using a focusing screen such
as the Brightscreen #5 diagonal split image with microprism collar? I always try to
fine tune using this focusing screen after auto focus or in manual focus.
DIGLLOYD: Live View is the only technique that can guarantee critical focus, though even then, some fast lenses have some focus ambiguity due to aberrations, though this is still small compared to typical autofocus error with fast lenses, or “green dot” focus assist.
Nikon Camera Control Pro: I don’t use this software, so I’m unsure of its behavior. But it’s easy to find out: set the aperture to f/8, and simply look at the lens diaphragm through the front of the lens to see if the lens is stopped down.
Focusing screens: these can create metering accuracy issues, but the main issue is that there is no guarantee that the optical path to the viewfinder is the same distance as the optical path to the sensor. In fact, it almost never is, and it’s a matter of the amount of error. The choice of a microprism is center-oriented, and thus the focus lock and recompose technique (FLR) also inherently shifts focus when the composition is reframed. Many people are shooting at f/8 or other stopped down apertures, and so the effects of such issues are masked, but when shooting at f/1.4 or similar, study of the results will show the loss of sharpness.
Thorsten K writes
I'm using the Katzeye screen in my D700, and it works great and I love it. But I also need to confirm what you noted in your blog today: There was initially a considerable difference between the light paths, so perfect focus with the viewfinder prism did not coincide with perfect live view focus.
t took me a few weeks of ordering shims of different thickness from Nikon parts and trial and error until I got it to be perfect. I would not recommend this procedure to a casual user, and anyway it's sad that Nikon ships cameras like this. I talked to Katzeye, and they said this is very frequent and almost every body needs some kind of adjustment. The maladjustment is of course already there in the camera with the stock screen, just less obvious so probably Nikon thinks they can get away with it.
Anyway, now that it's calibrated, it is very precise, and I can even see a small front of back focus issue with an AF lens and take a good guess that it may require +3 or -3 fine tune, just based on what I see in the viewfinder. And for manual focus, it speeds up the process a lot. It's not perfect of course, for a subject without lines (i.e. soft fur), it does not work.
DIGLLOYD: my experience too (although I never tried shims). I think Canon generally does a better job with the “1” series pro bodies, but not with the Canon 5D Mark II, which is definitely off with my body.
