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10-19-2011, 12:07 PM   #1
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hyperfocal focusing, take advantage of huge DoF

I was walking around doing some casual shooting with my Q and my adapted Pentax 6mm F/1.2 lens today. This lens is really only decently sharp from F/2.8. I realized I should look at some Depth of Field calculations to do some hyperfocal focusing. To those not familiar, the hyperfocal distance is the distance you should focus your lens to get maximum depth of field. On the Pentax Q sensor with a 6mm at F/4, the hyperfocal distance is about 5 feet. That means that if I focus the lens to 5 feet, everything between 2.5 feet and infinity should be acceptably sharp.

The cool part about this is that with a wide field of view this lens gives, I'm not likely to photograph much at less than 2.5 feet on the street. So I set the aperture to F/4, focused to about 5 feet, set the mode dial to "A" and just snapped away. No need to refocus the camera between shots. This makes taking pictures really fast and encourages a kind of shoot from the hip style. Combine this with some Bleach Bypass or Toy Camera filters, and you've got some fun street shots!

10-19-2011, 03:26 PM   #2
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I'm paranoid about hyperfocus (which strictly speaking is the distance at which DOF extends to infinity). I give about 1/3 or 1/2 stop margin if I *really* want infinity in focus. So if the table says f/4 for the desired DOF, bump it to f/4.5 or f/4.8 instead, leaving the prefocus the same.
03-07-2012, 09:23 AM   #3
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So I just got my 03 Fisheye lens. With this fixed F/5.6 aperture, the hyperfocal distance is about 1.5 feet. This corresponds to just about the second to last tick mark on the left when focusing. This makes the fisheye a breeze to preset focus and just snap away, with everything between about 9" to infinity being acceptably sharp. :-)
03-07-2012, 09:50 AM   #4
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yes these guys confirm that






Last edited by Clicker; 03-07-2012 at 09:56 AM.
03-07-2012, 10:00 AM   #5
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The sensor size on the Q implies that diffraction starts playing a significant role at apertures of F3 or narrower. By stopping down to F4 or F5.6, you get a greater DOF but the cost is lower resolution.
03-07-2012, 10:25 AM   #6
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Clicker, love the ice pics!

demp10, I agree about the diffraction limits, but the 03 fisheye lens is a fixed aperture lens.
03-07-2012, 10:31 AM   #7
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QuoteOriginally posted by devorama Quote
Clicker, love the ice pics!

demp10, I agree about the diffraction limits, but the 03 fisheye lens is a fixed aperture lens.
and it's hardly the sharpest beast in existence in any case LOL, on a Toy lens i'm pretty certain Diffraction is not a concern
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