Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: andyp1969 on July 17, 2007, 09:55:40 am
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I would really appreciate your comment on this question.
I have a Canon 5D and a 24mm TS-E lens. I have done a test on the following set up in my back garden on a tripod -
Shot one using F8 and point of focus i.e. line on depth of field scale set at infinity all sharp including edges
Shot two same as above but using full depth of field scale i.e. infinity set at the F8 mark and 5feet set at the other F8 on the scale - centre is sharp but edges are soft.
Why are the edges soft??
Any ideas.
Kind regards,
Andrew
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Sorry I'm not a technician so I can't answer your question, however with the tse lenses it's very easy for the lens to "magicially" have tilt applied. Make sure your tilt is zero'd out no amount of tighting can prevent it, always double check
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How are you assessing sharp/softness? Don't forget that the DoF scale on the lens is calculated for an 8x12" ~ish size print viewed at 10-12". If you look at the distance mark where shot two was actually focused (i.e. somewhere between 5' and infinity, you could calculate the anticipated DoF for that focusing distance using different CoC values using DoFMaster (http://www.dofmaster.com/dofjs.html) on-line. The most extreme case would be to use pixel-size as the CoC if you're pixel-peeping unashamedly (i.e. viewing at 100%). DOFmaster typically uses the old values for FF cameras like the 5D (0.03mm), but the pixel pitch is ~0.008mm. ( For 0.03mm, DoF is ~4' to infinity, for 0.008mm it is 6.3' to 10.9 ft )
The more closely you look at the acquired image, the less DoF you actually have. This should help calibrate your expectations, but there may still be an issue with the lens
Andy
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I'm off to get my hip boots
How are you assessing sharp/softness? Don't forget that the DoF scale on the lens is calculated for an 8x12" ~ish size print viewed at 10-12". If you look at the distance mark where shot two was actually focused (i.e. somewhere between 5' and infinity, you could calculate the anticipated DoF for that focusing distance using different CoC values using DoFMaster (http://www.dofmaster.com/dofjs.html) on-line. The most extreme case would be to use pixel-size as the CoC if you're pixel-peeping unashamedly (i.e. viewing at 100%). DOFmaster typically uses the old values for FF cameras like the 5D (0.03mm), but the pixel pitch is ~0.008mm. ( For 0.03mm, DoF is ~4' to infinity, for 0.008mm it is 6.3' to 10.9 ft )
Andy
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