effects of shutter speed on color of light

This first photo is really a composite of the two other photos. You will notice that there is a yellow color cast from the light that is obvious on the sofa.

This first photo is taken with a 1/20 exposure. Because the flash was on Manual, the camera did not try to meter for the flash.
















This second photo is taken with an exposure of 1/125 of a second. The shorter exposure really doesn't let much ambient light in, but because a flash duration is so short, the shorter exposure has no effect on the amount of light received from the flash. You will note that there is no yellow color cast.

This demonstrates that one way to remove the color cast of ambient light is simply to "overpower" it with your flash, in this case done with a shorter shutter speed. There is still enough light from the flash alone to properly illuminate the picture.

There was no attempt to "blend" the two light sources in this example.










This last photo is also at 1/125th of a sec but without the flash. Here you can see that at that shutter speed, very little ambient light contributes to the light of the photo.