Help needed
Some months ago I bought a second hand Canon lense 24-105 L f:4 IS. It looked great and worked great. But after some shots I saw that it has a serious problem. I searched the internet and after some time I found that other people also complain about it, but not that many to damage its stats on serious pages and shops. So maybe only few of them had this problem. Many people called it diffusion, others lack of sharpness. They claimed that it was reduced or even solved, by stopping down the lens. I saw small difference when I did use a close aperture and anyway, what’s the use buying a lense with IS and f:4 if you can’t use it at night? By the way it does this thing with all the digital cameras I use, but then again there are times that the sharpness is back !!! In either case I see through it crystal clear, but I get these lousy results.
Anyway, I am posting this photo today, that reveals the problem quite clearly. Any ideas of what it could be, and if it can be fixed by me, would be greatly appreciated.
Vassilis D. Gonis 
i’d like to help but i can’t. intermittent problems are the worst… you can’t reliably circumvent them. good luck finding a solution!
My thoughts exactly. That is why (apart from money) I was searching for similar cases and solutions via the Internet, before I turn it over to an authorised technician. Thank you anyway!
The sad part is you’re worst photo is still better than my best one. I did get a Sony RX100 which I’m still learning.
Jeff, there are bad photos and there are good photos. And then again there are photos with a purpose and photos without one, (or maybe not a right one). But believe me, if I was only doing it for kicks I would have stayed with by old analogue cameras. But work demands sharp lenses, fast responding cameras and quick digital results.
I wish I could help but I’m strictly a hapless digital camera user and also what Jeff said! Your photo looks good to me! But I do hope you’ll find the solution.
😉 It makes two of us! Or maybe three, counting Jeff!
Have you checked the IS? But I don’t know it really, because I have another system.
Sometimes it could help to clean the contacts.
???
My initial thought was the IS, and the placement of the moving parts after it is off. I have tried the contacts, but to no avail. Thank you anyway!
Strange you should see through it okay and yet get a result worse than you see. Is it maybe a software problem in that the camera has not been updated to include this particular lens? Of course stopping down to f/8 or so should help a little too.
One of my thoughts was colour aberration, which wouldn’t appear at the naked eye, but no way to confirm, or even worse fix this on my own. Thanks anyway, I will let you know!
Maybe an update for the camera software on the Canon web site?
Thank you David. Checked and I already have the latest update. I wonder if I am too touchy with it, or even if I am expecting too much from the combination of camera-lens, but my 17-40 without IS is so sharp at any f stop that I just can’t bear it.
Vassilis. I think all of your problems can be resolved if you use a tripod.. for all of your photography. If you are already using a tripod , I think you can solve your problems by selling the lens.
Thank you! You made me smile with the “selling the lense solution”. Perhaps it is the only solution! I just don’t want to create the same problem to the next buyer.
You know what they say, “one photographer’s waste basket is another photographer’s career.” I’m sure there’s a photographer out there who wants fuzzy images.
First time I hear it! A perfect saying! But why let anyone else steal this career? 😉
Mysterious. Perhaps it will become an ‘artsy’ lens. Smear some Vaseline on it a give it a go! : )
Bahh, there is always an explanation. Just hope it is not an expensive one! I don’t know about vaseline, but my daughter is doing a pretty similar job with her sticky fingers!