[tim0306blue]

I can't work out what happens if I take a shot on aperture priority using the cameras built in flash. Presumably varying the aperture has the same effect on DOF, but what happens if the aperture is wide and the shutter speed is fast? Will the camera adjust the timing of the fill-in? Maybe I am making this harder than it should be. I have a Nikon D80, in this case using 50mm lens.

[silkstone]

Let's take it one step at a time.

Exposure....

With most cameras (and I'm sorry, I can't be sure about Nikon) the auto flash exposure is mainly separate from the camera's own auto exposure. If you set the camera to shutter or aperture priority, it will determine the aperture/shutter speed as if the flash was not there. If you fire the flash as well, it will be 'fill-in', but it won't affect the aperture/shutter speed. On some cameras you can set a custom function to reduce the flash output in fill-in mode.

If you set the camera to manual exposure, you can dial in any aperture and shutter speed (up to the maximum X-sync which is normally around 1/250). As long as the flash itself is set to an auto mode (ETTL or whatever), the flash exposure will be automatic. In other words, the flash will deliver the right amount of light for correct exposure, based on the (manual) settings of the camera.

Going back to your question, Av mode with flash is the same as Av mode without flash, except that the flash will provide some fill light. If the flash is switched on, the camera should not choose a speed faster than the max X-sync. If you've chosen a wide aperture in bright conditions, the shutter speed display may blink at you to tell you it can't go fast enough and the shot will be overexposed.

Hope that makes sense!

[Dabhand16]

On the D70s you can also dial in flash exposure compensation to fine tune the flash. I used to have mine set to -1/3 of a stop. I can't believe that the D80 will not have this feature.

I can't for the life of me remember using it with shutter speeds over 1/200, so I don't know if the camera will limit the shutter speed when the flash is in use.

I imagine that if your settings will result in over or under exposure, you will get a warning in the LCD and the viewfinder.

From the ideal exposure to give balanced light if shooting outdoors, a faster shutter speed will underexpose the background and a slower speed will overexpose the subject, so varying your aperture will have this effect depending on how the camera sets the shutter.

Matrix metering is best if you want to balance the light, or maybe centre weighted as a second choice.

I think some experiments will give you the answer.

[tim0306blue]

Thanks very much for the advice - I will tinker with the settings and see what the results look like.