« on: May 25, 2014, 01:16:15 PM »
For usable resolution it isn't even just about the system (sensor, AA filter, lens, firmware etc), that just gives you a potential resolution in best case scenario situations that most of us practically never shoot in, and require 10x Live View manual focus, optimal aperture for lens sharpness, minimum or base iso (if we take the time and trouble to work out our sensors true base iso), very good light with high contrast, very firm support, cable release etc etc.
Now that list sounds like a landscape and architectural shooters M.O., and I believe they are the only people who will get any remote chance of worthwhile resolution increases when going over 30MP in the 135 format etc. Having said that I do a reasonable amount of higher end real estate work that is regularly used in quality print advertising as well as posters and billboards and I haven't found 21MP to be a serious limitation. Peolpe who use AF, BIF, sports shooters, action shooters, most wedding shooters etc will get practically nothing from a 30+MP sensor over current models.
After some extensive testing I did with the 1Ds MkIII and the 7D (sure things are better now but they are better for both formats) in ideal shooting situations set up to maximise the difference between the 21MP sensor and the effective 46MP sensor that showed minimal resolution differences, I concluded the numbers mean very little, in real world shooting situations where I was using AF and not optimal iso and aperture settings the differences disappeared completely. In truth AF had a far bigger impact on resolution than a 21 or 46 MP sensor.
If I shot landscape 100% of the time I'd use TS-E's on an A7R where the methodology of realising the potential resolution wouldn't impact my shooting, but I don't, I am a generalist and need AF, a range of ISO's, apertures, and shutter speeds, zoom lenses, etc etc.
In conclusion, I am not saying, and never have, that a higher MP sensor doesn't resolve "more", it does, but the rule of diminishing returns kicks in for virtually all real world shooting scenarios and makes the difference so small as to be imperceptible most of the time. Having something because it has a higher number is a game I stopped playing long ago, I look very closely at what it can actually do for me, so far the disadvantages of higher MP sensors in 135 format have not convinced me that Canon don't know far more about this than us and they hit a sweet spot with the 5D MkIII. I am a long time 1Ds MkIII user, if they come out with a true replacement in the 35-45MP range I am not interested, if they come out with a 1DX MkII with a 24MP sensor I died and went to camera heaven.