QUOTE(TrialGone @ Dec 7 2017, 05:54 PM)
A bit of misconception. If the lens is not sharp, it may actually look sharper on FF cause pixel size is bigger, provided if mp count the same on both Sensors. Your scenario of taking only the crop part for sharper corner result only works if lens is super sharp.
Your scenario where fullframe should be sharper than a crop only works if the lens is a very good lens.
Performance of a lens is not constant from the middle to the corners For high end lenses, the drop in performance is negligible.
But for cheap lens, that can be very apparent.
The performance at the edges and corners can be many times worse compared to the centre. Especially at maximum aperture. Any advantage the larger pixel size provided might not be enough to offset this.
Having said that. I believe the issue is due to
1. Comparing new crop camera and older full frame is not just about pixel and sensor size. The image processing plays an important role as well. Newer cameras might produce a more contrasty image.
2. Erwin might be using a cheap zoom lens at the longest focal length will yield bad results around the edges.
To be sure, you can check the MTF curve around the edges. But I'm sure the performance will be worse even considering the larger pixel size.
3. Performance degradation in the same camera over a few years should not happen unless it's damaged(extremely heavy use until the sensor and mount is misaligned for example.) or fungus/dust.
4. 5D2 focusing performance is not good. He has just forgotten how bad it was at missing shots due to focus.
But having said that, I think it's hard to say without knowing the exact lenses used and since he asked this quite some time ago, I assumed it has been resolved.
This post has been edited by LegendLee: Dec 8 2017, 08:31 AM