35mm close zone focus

ishanm

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Oct 11, 2010
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I've recently picked up an M6 and a Voigtlander 35/2.5 and came across this comment on Steve Huff's site. In it, the poster says that setting the focus point to 2m/6ft will result in a 6ft by 6ft box right in front of the camera (3ft left and right, 6ft in front) being acceptably in focus at any aperture. Since a lot of my photo opportunities tend to be indoors, and usually after dark, this method of focusing would be fantastic if it were true (especially if it's an evening where we've decided to go out for drinks).

I tried this over the weekend at an apartment party and found my results to be slightly hit and miss. This could very well be a fault of mine since I'm getting used to shooting with the M6 at slow shutter speeds, so it might not have been the best time to try this out. I've been trying to think of a way to test this out for myself, but I can't really come up with a test that would convince me of the statement's validity. I did run a search for 35mm zone focusing, but that didn't seem like a very limiting search and I couldn't find an answer looking through the threads. If I did miss it, I apologize.

So, is the statement made by the poster a valid one? And is there some way that I could test it out?
 
It's not true even at f16.

At f2.5 and 2m distance you have a bit more than 20cm DOF on either side of the focus plane (22 in front and 28 behind, to be exact).

Roland.
 
The 2m setting for a 35mm lens seems awfully close to me. What I'm using in a pinch is a more conservative 100x focal length snap-shot setting. For a 35mm lens, that would be 3.5 meters. Looking at DOF scales on lenses, you'll notice that when you get to about 100x the focal length, the DOF quite quickly expands considerably..
 
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