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-   -   Perfect Sharpness and Depth of Field (http://www.digitalcameraworld.com/forum/showthread.php?t=8130)

 AndrewMaz 04-01-12 12:52 PM

Perfect Sharpness and Depth of Field

Hi, I'm new here so, even though I have looked through the forums for guidance, and been through any number of websites and books, I am still unsure of what most outdoor photographers do to achieve perfect sharpness throughout the depth of field in their images.

So please, bear with me with this question:

What method do you use to achieve perfect sharpness throughout your photographs which have significant depth of field?

Do you shoot using the principles of calculating hyperfocal distance and focusing on that point? Or do you set your focus ring to infinity as is sometimes advocated? How do you calculate your hyperfocal distance? And how do you measure it in the real world given most of my photography will be on a hillside or whilst mountaineering?

I know this might seem a pretty basic question, but let me say why I am asking it - I have an iPhone app which calculates hyperfocal distance. I set my circle of confusion at 0.019mm which is apparently the setting for the Canon EOS 60D. I will be using a Canon 17-40mm f/4L lens when mountaineering. Some pro photographers set the CoC lower if they know they are going to print images at A3 and above - does that mean I should consider this to get better sharpness?

Once I have my CoC and focal distance set in the iPhone App, I get my hyperfocal distance - I get that, but I suspect you don't whip out a tape measure on the mountainside - do you just estimate then?

If you are shooting at f/8-f/11, which I know is around the sweet-spot for sharpness for most lenses, and you select 17mm focal length, with a CoC of 0.015mm, the hyperfocal distance is 2.43m and the area of sharpness is 1.94m to infinity. Sounds fine to me but how would you measure 2.43m (or even 2.5m) on the hill in reality? Do you focus on something manually or autofocus, lock and then recompose?

Hope you do not mind me asking and thank you in advance...!

 GeoffWessex 04-01-12 10:30 PM

Accurate calculation of hyperfocal distance isn't all that easy, but see if you can get your head around [URL="http://www.cambridgeincolour.com/tutorials/hyperfocal-distance.htm"]this guide[/URL].

 markgozz 04-01-12 10:52 PM

I use a chart just like the one in Geoff's link and once I set the aperture and focal length of my lens I then use the focus scale marks on the lens to set the focus distance , just one thing to remember is that at relatively small apertures the shutter speed can be quite slow so be prepared to take a tripod with you .

Mark

 AndrewMaz 09-01-12 08:46 AM

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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