Need Help With A Rebel XT Question

Pentax DA 18-55mm f/3.5-5.6 AF

08/06/2006 07:41:34 PM · #1

Iam using a Rebel XT with a Canon EF 28-135mm F/3.5-5.6 IS USM Lens.
Issue: When I focus on a subject at 135 The photo often lacks clarity (soft focus). When I take the same shot by focusing at 28 the running out the zoom, I get better results. Camera problem? Lens Problem? Operator problem?
Thanks. Jim Roussos

faidoi

Pentax K10D

08/06/2006 07:50:10 PM · #2

Post a picture and the EXIF infomation of what you are speaking of. Might possibly any number of problems.

Canon EF 24-70mm f/2.8L II

08/06/2006 07:53:27 PM · #3

Originally posted by faidoi:

Post a picture and the EXIF infomation of what you are speaking of. Might possibly any number of problems.

I can't from this computer, but I will post again. What are the possible problems?

chimericvisions

Canon EOS-60D

08/06/2006 07:54:40 PM · #4

At the very least, I'd clean the lens contacts on both the lens and the camera body. I've had issues before with soft focus, or refusing to focus at all.

Just use a soft (preferrably lint-free) cloth to wipe the electrical contacts.

Pentax DA 18-55mm f/3.5-5.6 AF

08/06/2006 07:55:33 PM · #5

Originally posted by chimericvisions:

I will do that- I wasn't sure what to use. Thanks

faidoi

Pentax K10D

08/06/2006 07:55:45 PM · #6

Originally posted by jrjr:

Originally posted by faidoi:
Post a picture and the EXIF infomation of what you are speaking of. Might possibly any number of problems.

I can't from this computer, but I will post again. What are the possible problems?

-The longer the zoom the more chance that there would be camera shake.
-Some lenses are softer at 1 or both extremes. Long end usually.

The odd part is the lens is a "USM". Hmmm.

Message edited by author 2006-08-06 19:56:52.

Canon RF 24-70mm f/2.8 L IS

08/06/2006 07:57:39 PM · #7

Ya know I did not think that it happens all the time. I will have to pay closer attention to see.

kirbic

Canon EOS R5

08/06/2006 09:19:13 PM · #8

Possible causes:
- Lens is just soft at the long end when wide open aperture is used. If the questionable shots are using f/5.6, this might be the issue.
- Camera shake. If you're shooting at less than about 1/200s handheld, this might be the issue.
- Back (or front) focus. This would be most apparent at the long end, and it's not an unknown problem. It would look worse when the lens is used wide open. It may be hard to differentiate between this and overall softness at the long end.