02-17-2011, 01:56 PM
[quote name='PuxaVida' timestamp='1297947635' post='6190']
Yeah, a simple workaround to avoid the problem...
And just out of curiosity... how can we distinguish residual spherical aberration (focus shift at closed aperture) from field curvature? Is the field curvature effected by the closing of the aperture?
Serkan
[/quote]
If you have focus shift, you simply have a miss focussed image. The camera focusses wide open, and when the aperture closes for exposure, the focus shifts. And you get out of focus results.
Field curvature, you get in focus centers and out of focus edges. Usually only noticeable when the corners are supposed to be clearly in the same focal plane as the center, but OOF.
Yeah, a simple workaround to avoid the problem...
And just out of curiosity... how can we distinguish residual spherical aberration (focus shift at closed aperture) from field curvature? Is the field curvature effected by the closing of the aperture?
Serkan
[/quote]
If you have focus shift, you simply have a miss focussed image. The camera focusses wide open, and when the aperture closes for exposure, the focus shifts. And you get out of focus results.
Field curvature, you get in focus centers and out of focus edges. Usually only noticeable when the corners are supposed to be clearly in the same focal plane as the center, but OOF.