Dave McGaughey wrote: gdanmitchell wrote: bhollis wrote:
Seeing lots of differing reports. Makes me wonder whether copy variation might be at play here. Copy variation could be with the particular camera, adapter and/or lens used in a given test.
Given the differing results, and all the caveats and qualifications we\'re seeing for even the lenses that supposedly work well, I\'m coming to the conclusion that the only way to really know how well a particular lens will work for you is to try it on your A7RII with your adapter and your Canon lens.
Besides \"copy variation,\" there are potentially other factors, too.
1. Operator technique — subject and lighting variations, etc.
2. Confirmation bias — in both directions.
Dan
I\'d say those two, along with \"expectations,\" are much more important than \"copy variation\" in this situation.
Given that the A7RII is now exclusively using PDAF sensors, which are WAY smaller than what are on a DSLR, it is not surprising that longer lenses just flat out don\'t work. I think physics may be the problem here.
I used to understand the difference in the AF method more clearly, and should probably review them. However, I recall that methods like those in use on the Sony sensor can be very accurate but are not able to as quickly determine the direction of the needed correction (focus closer or farther?) compared to systems typically used in DSLRs. So they can seem to hunt a bit more.
My hunch is that at some point designers will address this fundamental issue by simply speeding up the AF process on such cameras to the point that even though they \"hunt,\" they will do it so fast that the overall performance will be very good.
Dan
Aug 11, 2015 at 10:30 PM
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