How do I get my Canon Rebel XT to use the flash even if it doesn't think it needs it?

Question

I want to use it for beach shots and I want to go against the light. I want to use flash but am unsure how to get this to happen as it only seems to use it when it thinks it should. I must be missing some setting but I can't seem to figure it out. Help please.

I do have an exteranl flash also. I couldn't manage to experiment with it though since I couldn't get the flash to go off.

Answer 1

Are you shooting in Manual Mode? This will help, and allow you to apply it when you want.
On the side of the pop up flash, there should be a small button that looks like a crooked arrow pointing down. Push that, and the flash should pop up.

Answer 2

Yes, if you pop up the flash, you can force it to use it. But your question opens up a small can of worms. Here's the problem. The pop-up flash on your camera is only capable of a max 1/200 s shutter speed and the light that the pop-up flash can emit is not relatively bright. Why is that a problem? Because if you are at the beach in the middle of the day, you are likely getting flash speeds way above 1/200. Probably more like 1/2000. So if you are shooting at the fastest shutter speed that the flash can support, you are likely going to have highly overexposed images. Even if you crank down the ISO to its lowest setting and close your aperture so that you can get to a 1/200 shutter speed, your flash may not be powerful enough to be used as fill. (This is where the Nikon D70 shines, as it has a 1/500s flash sync).

Your best option is to invest in an external flash unit that is E-TTL compatible and supports the high speed flash sync mode that your pop-up flash can not support. This will enable you to use your flash with shutter speeds much faster than 1/200. There are some drawbacks to high speed flash sync but it works pretty well.

Here's a great article by Ken Rockwell on why flash sync is important, combined with flash output.

http://www.kenrockwell.com/tech/syncspeed.htm

Answer 3

Shoot in any other mode but the auto modes, i.e., aperture priority and force the flash on by pushing the flash button [usually on the side, near the lens].