topic Re: Focal issues with 24-105 L lens on 7D in EOS DSLR & Mirrorless Cameras

Focal issues with 24-105 L lens on 7D

Tamiww — Tue, 12 Feb 2013 15:37:05 GMT

Recently purchased a 24-105 L lens for my 7D and have found that in many photos are out of focus. Shot a group yesterday and took over 50 photos. Although the photos look o.k. when you get up close it seems nothing in the entire photo is sharp. Is anyone else having this issue and is there a fix?

Re: Focal issues with 24-105 L lens on 7D

ScottyP — Tue, 12 Feb 2013 18:18:59 GMT

Mine is really very sharp on my 6D.

1.) What other lenses have you shot with that you feel are working better for you?

2.) About this group shot: How big a group, and how bright or dim was it, and especially, what aperture were the shots taken? It can be impossible to get a whole group in focus if you are shooting at f/4.

If you can shoot at f/8 or f/11 and you still have enough light to keep the shutter speed over 1/100th, it would give you more keepers.

Re: Focal issues with 24-105 L lens on 7D

Tamiww — Wed, 13 Feb 2013 04:03:55 GMT

Thanks for the info. It was only a group of 3 and yes mostly shot at F4. I cannot find anything in the entire photo that is sharp though. Maybe the shutter speed just is not fast enough as they were all under 1/100. Thanks again for the insight, very helpful!

Re: Focal issues with 24-105 L lens on 7D

digital — Wed, 13 Feb 2013 00:20:26 GMT

How many in the group and what was your F stop?

Re: Focal issues with 24-105 L lens on 7D

7D5D — Wed, 13 Feb 2013 03:06:37 GMT

Lens elements could be decentered or require significant AFMA. I would do some testing and if necessary contact Canon Support. It took me two copies to get a good one.

Re: Focal issues with 24-105 L lens on 7D

Tamiww — Wed, 13 Feb 2013 04:01:31 GMT

This is all new to me, can you describe how to test?

Re: Focal issues with 24-105 L lens on 7D

7D5D — Wed, 13 Feb 2013 04:15:38 GMT

On the road typing on a small portable device. If you can give me a couple of days, I can email you some substantial info on how to test.

Re: Focal issues with 24-105 L lens on 7D

schmegg — Wed, 13 Feb 2013 11:58:48 GMT

Have you tried with IS off?

There have been some reports of IS causing blurring with some copies (my copy is fine). So, if you had IS on, perhaps try some test shots with it on and off and see if you can see any difference.

Re: Focal issues with 24-105 L lens on 7D

Tamiww — Wed, 13 Feb 2013 14:51:43 GMT

Info on testing would be fantastic, thank you very much. Also will do some test shots with IS off to see if it helps. Thanks everyone for the help..much appreciated!

Re: Focal issues with 24-105 L lens on 7D

7D5D — Sat, 16 Feb 2013 12:29:14 GMT

Haven't forgot about you, still stuck on the road. If I recall I have some good testing links on my PC when I get home. Maybe someone can beat me to the punch and provide that sooner.

Re: Focal issues with 24-105 L lens on 7D

cicopo — Sun, 17 Feb 2013 02:41:24 GMT

Check out theinformation here on how to isolate which problem you may have.

http://photography-on-the.net/forum/showthread.php?t=857871

Re: Focal issues with 24-105 L lens on 7D

7D5D — Sun, 17 Feb 2013 16:13:04 GMT

Some more resources for testing your 24-105

Take note under the section "Principles of Optical Testing", Item 4 "An element just a bit off center can cause chromatic aberration, astigmatism, coma and edge softness"

http://www.canonrumors.com/tech-articles/how-to-test-a-lens/

http://www.lensrentals.com/blog/2012/05/testing-for-a-decentered-lens-an-old-technique-gets-a-makeover

There is no hard data to back this up (and I certainly don't want to make any false accusations) but I have read lots of post and comments where people have had QC issues with the 24-105 lens and had to exchange it for a replacement copy. I was one of them. My brand new copy (not from a kit) had a huge air bubble in the front element. My second copy has been just fine. Maybe these numerous post are misleading because of the mass numbers of this lens in the field compare to other lens. Anyway I think the 24-105 is a fantastic lens and one of Canons very best valued lens.

After your testing, if you think you've got a defective lens, get it sent in to Canon before the warranty expires. Good luck and post your findings if you wouldn't mind.