Thursday, August 09, 2012

Aha! Backgrounds with Aperture, Flash, and Shutter Speed



More flowers

I took these flowers in the midday sun using a flash. I expected things to be a bit more washed out; but, the camera adjusted for the extra light. So, the flowers are bright; but, the background looks darker here than it actually was. I think I'm starting to understand how shutter speed and aperture work together.

This was at f8.0, 1/250s, and ISO 160.

The Canon SX40 HS has a maximum aperture of f8. I normally shoot at 2.8 for DoF, except I was zoomed in here. For proper exposure, the camera increased the shutter speed to 1/250 as it could not close the aperture anymore.

In another picture, I was physically closer to the subject rather than zoomed in. The result, in the midday sun, was a blurry washed out background. The camera adjusted for the additional flash brightness through shutter speed; but, the aperture was wide open, allowing a whole lot of ambient light into the shot.

So, it now makes sense. Shutter speed=flash exposure. Aperture=ambient light exposure.

I wondered why photographers would even bother with f8, f22, or whatever small aperture. I can see that the bight subject, dark background result has a good aesthetic appeal. And, I can see that in certain circumstances, I might want the opposite, a washed out background. Good to know.
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