Ambient vs. Flash comparison

asfixiate · Jun 25, 2008

its a good opinion and a good point you're making. i was just giving what I thougt too.

I wonder how a ambient light vs flash debate would go...now that I have an external flash i hardly ever take shots indoors without it.

Big Mike · Jun 25, 2008

Me too. If I am indoors and going to use ambient light...I'll do my best to use directional window light...other wise I grab the flash and bounce it off a wall/ceiling.

asfixiate · Jun 25, 2008

I'm not doing anything crazy with lighting yet because I"m saving for my wedding but I do have an external flash...cheapo sunpak. Its like 1,000,000 times better than the popup flash.

i just turned off the light in my bedroom and took a shot of my dog sleeping. I think I've turned into a flash nazi honestly.

Would you have more control over exposure in a dark room with flashes than in a lit up room with flashes?

Big Mike · Jun 26, 2008

Would you have more control over exposure in a dark room with flashes than in a lit up room with flashes?

It depends.

When I shoot with flash, I will almost always put the camera into manual mode. Flash exposure is a result of the flash output and the aperture of the lens. Shutter speed (as long as it's withing the sync range) does not affect the flash exposure.
However, every flash photo is actually two exposures...one from flash and one from ambient. So while you are using the flash output and the aperture to control the flash exposure, you can use the shutter speed to control the ambient exposure at the same time.

So for your example, you could take a shot of your dog with the lights on, but if you had a aperture of F16 and a shutter speed of 1/200...the ambient light probably wouldn't register at all and it would look as if the lights were off. This is referred to as overpowering the ambient light.
On the other hand, if you wanted your flash shot to look a little more natural, with a balance of flash and ambient, then you might set your aperture (and flash power) to something like F5.6 and use a shutter speed of 1/30. That would get much more ambient exposure.

ISO has an effect on both flash and ambient exposure. If you have an automatic flash, you can use the ISO to get more ambient exposure while causing the flash to use less power.