Now we see through a glass, darkly...
- Apr 5, 2016
Thanks for the feedback! I expected my 80D to equal my 5DIV in resolution and it definitely does not for moon shots, macro, etc. I conclude my expectations are just out of line.
The thing about crop glass working better has me a little mystified; it is my understanding that using FF glass on crop means the sensor uses only the best part of the lens, avoiding the edge issues, especially vignetting.
That it does. But it also magnifies what flaws and resolution limits are in the center of the lens' light circle.
To display an APS-C image at the same size as a FF image, the enlargement ratio has to be 1.6X more for the APS-C camera. That means to get the same number of lines per millimeter on the finished image, the lens used for the APS-C camera needs to be 1.6X sharper than the lens used on the FF camera. If a lens used on a FF body has a resolving capacity of 850 lpmm (measured on the sensor), one would need a lens with 1,360 lpmm to get the same amount of resolution at the final display size.