D800 focus with 1.4 prime lenses is very variable and inaccurate

Started Jan 20, 2013 | Discussions thread
moving_comfort Veteran Member • Posts: 8,205
Re: I'm not surprised.

primeshooter wrote:

rtf wrote:

Hi. Maybe my views with regard to what I would personally expect from my camera equipment, are outdated, but what I see is a 36 million pixel sensor, f1.4 - with very limited depth of field, camera hand held, and a subject that is not 100% still. Your lens will not perform at it's best at f1.4 either. Why did you need to shoot at f1.4? You would still have isolated the background at f2, but gave yourself a fighting chance with a little bit more depth of field. I have a D800/D700/D7000 and I would not expect any of them to be at their best at f1.4. It's a big ask.



Sorry I don't rate your questions. Lv contrast af works fine, at 1.4 so why not pdaf? The d700 had no trouble. I shot at f/1.4 because I wanted to. Also a slight front focused f/2 would still not have looked as nice as f/2 properly focused. If you can understand that live view autofocusing works for this type of shot, and usually takes at least 3 seconds with greater ability for movement of the subject and photographer then your argument is invalid Of why this isn't working with PDAf autofocus.


I have to say that I'm mirroring RTF's thoughts a bit here Steve...  there were several factors working against getting perfect focus there, and it's well known that CDAF will give you more accurate focus 95% of the time - nothing new there.  f/1.4 acuity. f/1.4 DOF with moving subjects, PDAF and 36MP...  pixel-peeping's going to show you some physical limitations of today's AF systems.

I think we may be able to assess this situation better if we had another 36MP camera to judge against  As it stands, I suspect a perfectly-aligned and tuned D700 would have given you similar results in the same circumstances, it just would have hidden the AF limitations with resolution limitations.

I understand your frustration, but don't know if here's anything 'wrong' with your camera.  Maybe rent a high-end Canon and a fast prime, and compare?


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