where there’s smoke there’s forum fire
I wanted to post my article here, but the nikonrumors was always showing "Topic not found" if sent the topic.
now you can read form URL below,
about the AF-error and amateurish test ABC
http://www.photo-forums.com/WebX?50@186.2HXkclPYnQm.197849@.eeb39dd/0
Reading your posts I see a essay on (what I would have titled) "Lens aberrations and their affect on apparent focus." Would you agree with this?
What I don't follow, and perhaps you could help me out, is what you mean by "amateurish test ABC".
EDIT: Or is the issue that you haven't actually posted parts 2 and 3 yet?
"Or is the issue that you haven't actually posted parts 2 and 3 yet?"
Yes, there is now posted the Part 1, -- " Lenses caused the AF-errors to be most of the common."
Part 2 and Part 3 are being writing drafts, it is needed time to get posted.
when maximal aperture was same, but a shorter focal-length lens is usually with larger AF-error showed up in the maximal aperture. (despite the Nikkor 35mm f1.4G and 35mm f2D were with better state, but general cases still exist of foregoing that.)
when the focal-length was same, but a larger aperture lens is usually with larger AF-error showed up in the maximal aperture.
well then, the larger aperture of wide-angle lens existed of more difficulties.
excepting the macro lens, why the many lenses are such cases? (a short distance target and the AF-error in maximal aperture)
In essence, the said two situations actually have a same intrinsic factor, the off-axis beams of light have the higher obliquities would easily lead to a larger spherical aberration, and thus the autofocus-error will be risen, (for the PD-AF in maximal aperture).
However, looks the PD-AF having the larger focus-error in maximal aperture if got large spherical aberration, but the optimum imaging aperture is still to be likely a good accuracy AF, when lens had having a not bad design. The optimum aperture's imaging performance needed to get a priority consideration, that is frequently saw things.
Commonly, the maximal aperture's spherical aberration correction had to make the necessary compromises. Most of the designs were impossible to take blindly pursued the spherical aberrations get a zero, which is also impossible thing in fact.
You must log in to post.
