Luminous Landscape Forum

Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: Stephen Edgar on September 02, 2011, 02:43:44 am

Title: Help required to identify lens (or photographer) image quality problem
Post by: Stephen Edgar on September 02, 2011, 02:43:44 am

Hi Folks,
I would appreciate some help in identifying an 'image quality' problem that seems to have appeared recently using a Canon EF 28-135mm f/3.5-5.6 IS USM attached to a Canon 5D body
I have attached four files, two 'original' files and a cropped section from each original.
I am puzzled why the quality of the pictures is so (technically) poor, particularly around the edges (and particularly the left edge) of the images?
The centre of the images seems fine.
I would appreciate some expert insight in identifying if there is a lens issue or if perhaps the fault is simply poor technique from the photographer ;)
I must stress I am not a 'pixel peeper', but I am curious to understand the problem
Thanks in anticipation for any feedback,
Regards
Stephen Edgar

Title: Re: Help required to identify lens (or photographer) image quality problem
Post by: Jeremy Roussak on September 02, 2011, 02:54:42 am

Aperture?

Jeremy

Title: Re: Help required to identify lens (or photographer) image quality problem
Post by: Bryan Conner on September 02, 2011, 04:11:52 am

My guess is that the lens is decentered.  If you would like to investigate this possibility yourself, instructions (and advice) to do so can be found at http://www.photozone.de/lens-test-faq  . 

Title: Re: Help required to identify lens (or photographer) image quality problem
Post by: David Sutton on September 02, 2011, 04:15:28 am

I took the liberty of looking at the metadata and your aperture and shutter speed look fine. So it comes back to a lens issue. I hear this lens is quite good on a crop sensor but some have shown problems on a full frame at the edges. It may be worth having it checked. They can also fail "out of the blue", as I've found to my cost.

Title: Re: Help required to identify lens (or photographer) image quality problem
Post by: Stephen Edgar on September 03, 2011, 03:31:47 am

Thanks everyone for the input. It was appreciated!

Stephen