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Difference between exposure and flash compensation?

Barry Irvin , Jan 20, 2000; 05:55 p.m.

I own a Nikon N70 and I would like to know what the difference is between using flash compensation and exposure compensation. If my camera is using TTL metering when I use the flash I'm confused about what difference it would make to use one or the other.

Responses

Ellis Vener , Jan 20, 2000; 06:05 p.m.

Flash compensation only effects the flash exposure. Exposure compensation effects overall exposure including only ambient andflash exposure.

DJ Soroka , Jan 20, 2000; 06:14 p.m.

Exposure compensation (set on camera) under or overexposes the foreground and background, flash compensation (usually set on flash, but some cameras have this option on them as well) under or over (usually under) exposes the foreground only. This is a way to balance your ambient and flash light.

Preferred lighting ratios of ambient to flash are typically 2:1 to 3:1, which means your flash would have a minus compensation of -1 to -1.6 f/stops. If you set both exposure compensation on the camera as well as on the flash, they are additive. For example, if you dial in +1 compensation on the camera, that will overexpose the foreground and background by 1 stop. If you simultaneously dial in flash minus compensation of -1.3, your background would be overexposed by one stop, and the foreground would be -0.3, which is a difference of 1.3 f/stops, or a 2.5:1 ratio.

Frequently, if you need to let in more ambient light, you can manually set a slower shutter speed, use rear curtain sync, or some other method (more than one flash, slow sync, multiple firing of one flash) to accomplish the effect that you desire.

DJ Soroka , Jan 20, 2000; 06:22 p.m.

To correct my last statement above, the use of multiple flash or multiple firings of one flash are methods that can be used in low light, but they do not let in more ambient light.

T A , Jan 21, 2000; 08:00 a.m.

In this photo (EOS50e + 380EX) the ambient compensation is -1 f-stop with no flash compesantion. Result: main subject correctly exposed, with dark-looking (it was evening) background.


Example on flash/ambient compensation use

Stephen Schoof , Jan 21, 2000; 11:24 a.m.

Also please note that the N70's auto-bracketing feature affects only ambient exposure, not flash. So you can set flash to, say, -1.0 and auto-bracket your ambient exposure at -0.7, 0, and +0.7, getting -1.0 on the flash the whole time. If you manually bracketed with the exposure compensation control, you would change the whole (ambient AND flash) exposure each time (getting -0.7, 0, and +0.7 on ambient, and -1.7, -1.0 and -0.3 on flash).

john linn , Jan 21, 2000; 11:44 a.m.

we've been through this... Canon and Nikon systems operate differently in regards to flash and exposure compensation. For Nikon users, Ellis' answer is correct.

Antonio Quinones , Aug 03, 2003; 01:23 p.m.

Follow up question to "Difference between exposure and flash compensation?"

So, if I dial in a -1 stop flash compensation in the N70 does the cameras's aperture/speed combination (in program mode) remain the same or does the camera change the A/S settings to gather more ambient light and compensate for the loss in flash output?

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