It is possible to derive the necessary FF megapixels that would produce the same fineness of detail as an 18mp APS-C sensor if you were interested.
Yes, well I do have the math for that here already, it's not what I meant. I might have gotten a little confused about the right terminology. I'll attach a table with the numbers for a couple of cameras.
That article you posted will take me some time to read through, but I bookmarked it, so thanks!
A sensor with 1000 height cells is able to resolve about (1000*0.75)/2 = 375 lines.
Ok, now I'm still not sure what to do with that formula to get to my goal.
Let's have a look at these MTF charts:
Canon 50/1.4 on 350D (350D is APS-C and has 2304 height cells):
Canon 50/1.4 on 50D (50D is APS-C and has 3168 height cells):
Canon 50/1.4 on 5D2 (5D2 has 3744 height cells):
Now these MTF figures were derived from images that were taken with 8MP and 15MP (APS-C) and 21MP (FF) bodies. Comparing the 350D and 50D figures, they look kinda (oh well...) the same except being cut off at some point (around 2050) by the 350D. Now that cut-off-point, could that be 2304 height cells minus the AA-filter effect?
The question remains: Are these charts in any way helpful on determining if a sensor with a given pixel size (e.g. 4,31µm) will be outresolved by a certain lens at a certain setting?
Also, given this situation: A certain lens (lets say the 50/1.4) is tested on a certain body (350D). The MTF figures at a certain setting (1.8 ) are clearly lower (1850 LW/PH) than the maximum the camera can resolve (lets say 2050 LW/PH for the 8MP 350D). Can we assume that a higher resolution sensor of the same physical size will not give us any more picture detail? I know the charts above say differently - but why?
(OR could that be due to inaccurate measuring (the tests were a couple of years apart) or assembling deviations (no two lenses are the same)?)
Again, what I found was, that when you take an 18MP picture with the email@example.com on an APS-C camera, downscale it to 8MP and reupscale it to 18MP, there is no loss of detail (at all). Thats why I figured that this lens @1.8 doesnt even outresolve an 8MP APS-C sensor, which I think is supported by the MTF figures above.