Just to understand (field curvature and other stuff...)

Thread Rating:

0 Vote(s) - 0 Average
1
2
3
4
5

Thread Modes

Just to understand (field curvature and other stuff...)

stoppingdown Offline

All-Star

Posts: 1,005
Threads: 182
Joined: Oct 2013
Reputation: 7

01-13-2014, 10:46 AM

So, let's suppose I did this:

put the camera on a tripod and make sure everything is stable
autofocused on the center (a far subject, let's say 500m) and took a shot
switched to manual focus (and took another shot for a consistency check)
rotated the camera so the subject is placed at left and right border, and took two more shots

The border shots are in general less sharp than the center, as usual. Let's forget defects for now and suppose I'm fine with the results.

Now let's suppose I re-took the border shots, this time by reactivating autofocus, and autofocused on them by moving the autofocus cursor. In these shots, the focused border is sharper, but the center is worse than before.

Is this a normal behaviour, right? Is it due to field curvature? I have other questions, but first I'd like to understand whether I'm totally off track or not.

stoppingdown.net

Sony a6300, Sony a6000, Sony NEX-6, Sony E 10-18mm F4 OSS, Sony Zeiss Vario-Tessar T* E 16-70mm F4 ZA OSS, Sony FE 70-200mm F4 G OSS, Sigma 150-600mm Æ’/5-6.3 DG OS HSM Contemporary, Samyang 12mm Æ’/2, Sigma 30mm F2.8 DN | A, Meyer Gorlitz Trioplan 100mm Æ’/2.8, Samyang 8mm Æ’/3.5 fish-eye II | Zenit Helios 44-2 58mm Æ’/2
Plus some legacy Nikkor lenses.

Website Find