Looking at GRD IV - read about focus problems?

Started 9 months ago | Questions thread
Tom Caldwell
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Re: Looking at GRD IV - read about focus problems?
In reply to schaki, 9 months ago

schaki wrote:

Seems no better than that Ricoh almost reinvented the hit and miss AF which affected at least some of the Ricoh Caplio R5. Could this be related to the PDAF maybe which both R5 and the GRDIV have got? I doubt it is the IS but these which have the focus problem can test to turn off the IS and test if the problem still is there. The GRDIII didn't have PDAF as far as I remember and maybe not IS either.

Considering this problem seems enough widespread (has not seen possible topics on Flickr on this subject yet) Ricoh should fix this problem without cost even if the camera is out of warranty.

Schaki

You have probably nailed it there.  The PDAF was and is a brilliant idea but it is simply an emitted beam bounced back to a receptor sensor and must suffer parallax problems as much as an ovf might.  Conseqently in a busy oor distant subject area it might not be picking up the exact same object as the photographer is actually looking at..  Maybe a test at right angles at (say) three metres from a rough brick wall?  At right angles the focus should be perfect as using PDAF and quick. At a 45 degree angle the PDAF might not be so accurate.  Note that on the GRDIV there is such a setting as "auto snap" which is obviously a quick press of the shutter and focus = PDAF only.

As a slow soft press shutter man myself maybe the PDAF has had time to hand over to the hybrid supplemental CDAF for finessing the accuracy of focus. Perhaps that is why I have not noticed any problem with my GRDIV but others have.

Therefore those doing quick press might be getting PDAF only - maybe not always a problem but all talk of PDAF I have read has said it is super-quick but not as precise even "through the lens dslr" and can need a touch of CDAF for final ultimate precision.

Maybe it is not so much as a fault of the camera but a needed understanding of what the camera is doing.

PDAF via the GRDIV "window" is quick but if ultimate precision is lacking then take a deep breath and slow the shutter press down.

Of course we must pay tribute to Ricoh for even daring to give any of its compact cameras the PDAF capability.  I am not sure that any others have done this. I am certainly not wishing away the PDAF capability in my GRDIV.

Maybe there is a way to temporarily shut the PDAF down so that comparative testing could be made.

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Tom Caldwell

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