Wednesday, July 01, 2009

A Tale Of Two F-Stops


Here's a short lesson in photography for you. Both of these pictures were taken with the same camera, one right after the other. The only setting I changed in between the two shots was the f-stop. The one above was shot through a really small opening, something like f/22. The one below is wide open, f/4 I think. Notice that in both cases the mushroom is in focus, but the picture above has more of the leaves around the mushroom in focus, while the picture below has out-of-focus leaves. That's depth-of-field. The rocks in the background are in a stream maybe 20-25 feet below the mushroom, and they are almost in focus above, but you'd have a hard time telling what they were in the picture below. Cool, eh? Problem is, to get the wide depth of field (the small f-stop or larger number), you need a longer exposure. I was using my new tripod, and the exposure probably took 20-30 seconds. There's always a trade-off.

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