Originally posted by Sliver-Surfer Simply put between a current 24mp aps-c and a 24mp FF a 400mm aps-c lens is going to transmit so close to the same quality image on both cameras. I'm not going to get into a brand war here because I like both brands. A6000 is far from a crippled camera read some reviews.
Man what you say is that the FF sensor outresolve the lense so there no much improvement to expect with more pixel density.
So I went to Dxo try a 400mm lens (Nikon 400mm f/2.8) on D810 and D750...
On the D810, the lens is rated as 33MP while on D750 it is rated at 24MP and on D7100 17MP.
What can we conclude?
- the 24MP sensor doesn't outresolve the lens by far. This is the contrary as even with the D810, the score is near the max resolution of the FF camera. Likely such lens would continue to get better score with an FF camera with much more MP
- The 24MP FF sensor get 24MP from the lens. But cropped to APSC size, remain only 10.5 MP while the D7100 get 17MP out of it. There significantly more detail out of the APSC crop.
But yes we look at the 80-400 from Nikon then D7100 get only 9MP while the D750 get 17MP so here clearly there no much to gain. Maybe the FF provide a wider image... but it doesn't provide more reach neither more magnification. The question if you want or not more folliage arround your bird.
I checked also the 120-300 f/2.8 from sigma and a D7100 get 16MP out of it while a D750 get 22MP out of it meaning the APSC crop can't be more than 10.5MP and then again we get a benefit from APSC. But apparently only from quite premium lenses.
To me the big question will be how the 150-450 will behave... Unfortunately it has not been tested.
At least from ephotozine on K3 it appear to be quite good and we could expect a noticable gain vs a 24MP FF... Versus a 42MP FF the question is quite different. Not sure.