Perfect Sharpness and Depth of Field
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09-01-12, 08:46 AM
Join Date: Jan 2012
Location: London, UK
Thanks for the responses
Geoff - thanks very much. I had seen and read that article, among countless others, but wanted to also see what other people were doing in the real world, if you'll forgive the vernacular.
I am likely to spend at least 40% of my time in the mountains, handholding and needing quite a bit of depth of field. Some experiments with my 17-40mm f/4L USM at 17mm led me to the conclusion that, handholding, the difference in sharpness between f/8 and f/11 was almost non-existent but the shutter speed, as Mark points out, is a major factor when handholding. Thanks Mark, that particular piece of advice, which is one of those obvious things I hadn't factored into handholding because I focusing on Hyperfocal distance issues, is perhaps the most important for my mountain photography.
What I did find was that setting a CoC of 0.019 gave me a HD of 2m at f/8 and 17mm. Setting the CoC at 0.015 gave me 2.5m. I found that my greatest sharpness from around 80m onwards at f/8 was achieved by focusing at 3m. There is a greenhouse at the bottom of my garden which is 80m away and I enlarged the image on the LCD screen of the camera (no time to download it yet) and there was a palpable difference in sharpness for the greenhouse when focusing at 2m and 3m (the latter being sharper). Everything in the foreground was pin sharp at both focus distances. However, I still found that the sharpness beyond 200m or so was starting to get a bit ropey but it may be that this is never going to be great without tripod, mirror lockup and remote shutter release and then f/13 or f/16...
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