View Full Version : Center filter needed on SA-XL WA lenses

8-Mar-2007, 07:08
Is the center filter only needed when using bigger apertures on SA-XL 90mm f/5,6 and 72mm f/5,6 ?

If so, at what apertures is the center filter needed ? I guess the 72mm is a bit worse than the 90mm ? Does it also depend on the part of the image circle of the lens used (tilt,shift) ?

Bob Salomon
8-Mar-2007, 07:30
A center filter will not work at large apertures. In order for the filter's rffect to be seen the lens must be stopped down a minimu of 2 stops. The fall off becomes noticeable 70% out from the center of the lenses coverage.