Canon 17-40 issues

Started Feb 19, 2013 | Discussions thread
Marquee Regular Member • Posts: 169
Re: Canon 17-40 issues

OK Some comments

  • You are shooting at F7.1 which is quite wide for a shot with foreground interest and detail at infinity on FF. I would be at F9-10 at least in this situation - F7.1 is pushing it for sufficient DOF
  • You may have a decentred element problem, the top left softness has a decentred look about it, but this may not be the case
  • The 17-40 has notoriously soft corners especially at the wide end, the lens is only really useable from 22mm or so and not below around F8. F7.1 is on the edge for soft corners from the 17-40 
  • I have noticed that lenses appear sharper at closer focus distances and certainly with the 17-40, corners have been soft when the DoF has appeared to be sufficient elsewhere in the frame (maybe due to a non flat focus plane - certainly the case with the 24-70 mki). I guess everything has to be just right to get the most out of the 17-40 and so some reviewing at 10% mag of the corners is essential on critical shots. Possibly some focus stacking (a few more shots shot with the lens focus set past the L infinity marking) would be of benefit


 Marquee's gear list:Marquee's gear list
Canon EOS 5D Mark III Canon EF 100mm f/2.0 USM Canon Extender EF 1.4x II Sigma 50mm F2.8 EX DG Macro Canon TS-E 24mm f/3.5L II +2 more
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