Focus Oscillation in K3 iii?

Started 4 months ago | Discussions thread
Ergo607 Senior Member • Posts: 1,481
Re: Focus Oscillation in K3 iii?

JoeOptics314 wrote:

I just received a Pentax 70-210 mm zoom and am comparing it against two other lenses that cover that zoom range (150-450mm and 55-300mm PLM). My initial shots comparing against the 55-300 mm showed it better in terms of blur, which would be quite surprising. But when I started taking pairs of shots a few seconds apart and compared the pairs taken with identical manual settings I see what appears sharpness differences.

Here are some samples, displayed in ON1 Photoraw. These are unprocessed raws taken 2 to 5 seconds apart with identical, F/number, shutter speed, ISO.

I am wondering if there is some parameter in the K3 iii menus that might be causing this issue? I am shooting hand held, but with motion compensation on at what I think are reasonable shutter speeds (1/125 to 1/800 sec).

AF Mode = S

AF Active Area = S

AF Area Restriction = On

Release Priority (Hmmm. Should I be using Focus Priority?)

The fact that I see this focus change problem with 2 different lenses, must me the issue is the camera? Have others seen this problem? I am hoping there is a different setting that fixes the issue.

70-210mm at 210mm F/5

150-450 at 200mm F/6.3

Why for the love of God are you posting photo's presented at 200% (or more?) magnification? That way it is impossible to draw any conclusions. It could be misfocussing, camera shake, shutter shock, or something else that I am not thinking about. Or it could be a combination of all those together.

FWIW, while there is a difference, IMHO it will be negligible in real world practice...

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