DOF question

F

felixlee

Member
Hi everyone, I just had a quick question about DOF. When you close the aperture down including reducing the amount of incoming light, does that increase the size of focus?

I remember hearing something about your actor sneezes and hes out of focus, and thats because you're wide open.

Im guessing that by stopping (up) closing the aperture I will be able to have more play with my actors moving away and toward me while still having my background out of focus.

Please correct me if I'm wrong.
 
Stopping down increases your depth of field. It's the opposite of what you said - if you want to have more wiggle room as far as focus, increase the amount of light and then stop down the lens. The easiest way to think about this principle is like this: if something looks blurry to your eyes, what do you do? Squint to bring it in focus. That's exactly how a lens works, more or less.
 
I misread your first post. You have your terminology all mixed up. Stopping down (closing) the aperture is increasing the Fstop. Also it's not size of focus but depth of field.
 
yes the more you open your aperture, i.e. the lower the fstop numbers like f2, f1.8, f1.4, then the more shallow your DoF will be. so at fully open aperture you might only have the character's eyes or nose in focus and the rest of his face and ears already start going out of focus. that's why a lot of people use ND filters for outdoors scenes. Because when it's really sunny outdoors without a filter you're forced to close your aperture so that your image is not completely overexposed with light, and thus you get really deep DoF so when a person wants really shallow Depth of Field outdoors, they put a ND filter to block the light and then they're able to still open the aperture a lot and not have it completely over exposed. hope that helps
 
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