Anyone know if Canon calibration can fix the following problem: The lens is real soft at 24mm at any F stop on manual or A/F. But very good at mid range to 70 zoom. This would seem to be an internal element adjustment to me. What say you guys?
1. Using a tripod frame your subject at 24mm, zoom to 70mm and focus on your subject using AF.
3. Zoom back to 24mm and shoot a frame without refocusing from the 70mm focus point.
4. De-focus the focus manually, then let the camera autofocus itself at 24mm and shoot another frame.
5. Compare the two frames to see if the first frame is more accurately focussed than the second.
The 24-70 is notorious for having autofocus "challenges" for some subjects under some lighting situations, but I've been able to work around them by focusing at 70mm and zooming back to shoot.
...and yes, my copy is as par-focal as could be hoped.
David I tried that on an object about 12 feet away and F8 and the shot was soft from foreground to background, in other words no part of the depth of field was good. I suspect the internal elements .
davidrwilliams wrote:
Before you send it in try this...
1. Using a tripod frame your subject at 24mm, zoom to 70mm and focus on your subject using AF.
3. Zoom back to 24mm and shoot a frame without refocusing from the 70mm focus point.
4. De-focus the focus manually, then let the camera autofocus itself at 24mm and shoot another frame.
5. Compare the two frames to see if the first frame is more accurately focussed than the second.
The 24-70 is notorious for having autofocus "challenges" for some subjects under some lighting situations, but I've been able to work around them by focusing at 70mm and zooming back to shoot.
...and yes, my copy is as par-focal as could be hoped....Show more →
David, when you say your "copy" is par-focal, does that mean that not all 24-70L's are par-focal?
...which is precisely why I said "my copy is parfocal", as anticipated that this debate would begin again.
Chuck Westfall's post #13 referenced above pretty much says it all. In my experience, if I focus at 70mm, zoom back to any other focal length without refocusing, and shoot, the resulting focus point remains sharp regardless of the aperture used for the shot.
