I'm trying to decide whether to pick up a Tamron 70-200mm F2.8 for my Nikon D7000 or for my Sony A850. One is 16mpx and one is 24mpx.
Lets say I took a picture of a landscape with a certain framing at 200mm on the A850 which I then had to crop a bit to get to the 275mm equivalent. On the D7000 that same framing would simply be within the zoom range because of the crop factor.
Now lets say I'm making a large movie poster sized print of this image, would I have better quality with the A850 or D7000? The dynamic range of both is very similar and lets assume base ISO.
- Similar vertical framing,
- Similar lens resolution at different zoom factors,
- Sony A850 has a sensor with a Nyquist frequency of 84 cy/mm,
- Nikon D7000 has a sensor with a Nyquist frequency of 104.6 cy/mm,
- Nikon relatively keeps 68 cy/mm Nyquist frequency at the same/normalized sensor size,
because the Nikon requires 53.8% more magnification for similar size output,
- the Nikon's denser sampling squeezes only a little (not enough) more resolution out of the lens
Leads to the assumption that the Sony will produce significantly sharper output on magnifications of more than, say, 10 inches on the short dimension. There are complicating factors such as differences in AA-filter which change the MTF of the system. However the Sony leads far enough to be safe.