04-01-2014, 08:59 PM
Ah, you're talking about 16MP on µ4/3 - well, in that case you're right, as the lenses have shorter focal lengths and usuallly are not very fast. So they are therefore less critical to focus with no big movements of the mechanics.
But even if CDAF might be more accurate and less needy to adjust, adapted on a FF it would be a pretty slow thing.
I agree basically with the advantages of on-sensor-focussing and also the problems with differerent adjustments on different distances (for primes) and FLs (for zooms). It's just, the PDAF is still more convincing to me on a D800 than the comparatively slow CDAF of the typical DSLR. But the bigger the sensor, the bigger the problems of AF and alignment of sensor, lens and AF module. I think, if we had sensors with high pixel counts in some cameras, we would easily see that those "low pixel" count cams would also have AF issues - not only the D800. And I also think, we are with those high MPs already very close to the limits of manufacturing in extremely tight tolerances.
I'm still wondering - as I wrote in the V3 thread - why no camera manufacturer came out with the idea of using the CDAF for adjusting the PDAF. That could be done with various distances and focal lengths. Camera on tripod, target (printed in the manual), LiveView - set the distance of the lens. Go to PDAF and check for the difference, the set the AF finetune values. This could be done automatically and without endless test series.
But even if CDAF might be more accurate and less needy to adjust, adapted on a FF it would be a pretty slow thing.
I agree basically with the advantages of on-sensor-focussing and also the problems with differerent adjustments on different distances (for primes) and FLs (for zooms). It's just, the PDAF is still more convincing to me on a D800 than the comparatively slow CDAF of the typical DSLR. But the bigger the sensor, the bigger the problems of AF and alignment of sensor, lens and AF module. I think, if we had sensors with high pixel counts in some cameras, we would easily see that those "low pixel" count cams would also have AF issues - not only the D800. And I also think, we are with those high MPs already very close to the limits of manufacturing in extremely tight tolerances.
I'm still wondering - as I wrote in the V3 thread - why no camera manufacturer came out with the idea of using the CDAF for adjusting the PDAF. That could be done with various distances and focal lengths. Camera on tripod, target (printed in the manual), LiveView - set the distance of the lens. Go to PDAF and check for the difference, the set the AF finetune values. This could be done automatically and without endless test series.