Originally posted by UncleVanya What's the basis of this? I can't say you're wrong as I haven't tested it yet. But I'd be curious what makes you sure. Also, as you said fill resolution isn't always required. My experience is that all lenses get better with higher resolution sensor but some get better than others. If expect my better lenses to look quite good. Remember I'm shooting on a k-3. The pixel pitch of that sensor is 3.88 micro meters, the Sony is 4.51 micro meters. Detail resolution is already more difficult on the k-3. At least that my understanding. But I'm also sure the lenses I have may not be as razor sharp as some others so your point isn't lost on me.
Well, I am not sure really what will happen in practice, so it is just a theory. Could be wrong.
Even though the K3 has a smaller pixel pitch, I am talking about the FF edge, the part outside the APS-C range. In that range, the resolving power of most Pentax lenses (and indeed most DSLR lenses) is not that great. From seeing the MTF and Imatest results of these lenses I have a feeling that the edge performance on a high-resolution sensor like the A7rii won't be that much better than the edge performance on the K1.
So, my point is not that the images coming out of that combo will be bad or anything. I actually think they would be good. My point was just that the area outside the APS-C crop may not be that much better than a lower-res FF sensor.
Also, definitely true that lenses 'improve' on a high-resolution sensor...but only up to a point.