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Tuesday, February 16, 2010

Hyperfocal Distance

Snowy Susquehanna
© 2010 Simon Hucko

Those of you who remember the days of manual focus and intricate depth of field scales painted onto the lens can skip this one (and try not to laugh too much on your way out). For the rest of you, I'm going to let you in on a little bit of physics magic that will take your landscape photos to the next level - the hyperfocal distance (wikipedia.org).

Sparing you the physics of it all, by focusing your lens to its hyperfocal distance you get as much of your image in focus as possible. This is especially useful for landscape photography where you want a sharp horizon but there are interesting elements in the foreground. Rather than focusing to infinity and losing some sharpness up close, you can focus closer and push that plane of focus into the foreground. The net result is a shot that is sharp from front to back, giving you the most detail possible. Another great advantage of using the hyperfocal distance is that you don't need to focus on your subjects as long as they're a minimum distance away. Just point and shoot - great for shooting without looking.

The hyperfocal distance is a property of the lens' focal length, selected aperture, and the sensor size. Here's a handy little depth of field calculator that does the math for you: DOFmaster. I've gone through and noted the hyperfocal distance for some useful focal length/aperture combinations so that I don't need wifi while I'm trekking through the mountains to get the desired results. Those of you with iPhones and whatnot can download a program that will do this for you on the go.

OK, so you've got the hyperfocal distance all figured out, but then realize that you have no distance scale on your lens! (Or the one that's there isn't very good.) Modern lenses (especially the less expensive ones) are designed for use with auto-focus systems, so they save money by removing the distance and depth of field scales from the focusing ring. Don't panic, you can fudge the hyperfocal thing by setting your aperture to f/11 or f/16 and focusing on something 1/3 of the way into the scene. There's no guarantee you'll get the maximum depth of field this way, but your results should be pretty good.

If you are lucky enough to have a lens with depth of field scales on it, you don't even need to look up your hyperfocal distance. Just line up the infinity focus point with the far depth of field line for the aperture you're using. Done. Simple as that.

Today's shot was taken at the hyperfocal distance for my lens (about 9ft at 18mm f/8, very convenient as that's the first value on the distance scale for this lens). You can see that the rocks in the foreground are in focus. It's a little snowy, but I assure you that the horizon is in focus as well.

So there you go, another handy technique to add to your photography tool belt.

~S

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1 comment:

  1. Beautiful shot! I love the sort of S-curve of the shoreline.

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