Rebel XT flash?

[Michaelmjc]

I was just outside taking some pics. I popped the flash up and went to take a picture, when the flash started goin off like a strob light. I almost had a seizure looking at it. It was on autofocus, and it doesn't seem to do it on manual focus... Anyone had that problem? Or know why it does that?

[Rigby470]

Michael,

Yeah, I know EXACTLY what you're referring to. What this is, is how the XT gets enough light to autofocus. There is not enough light for the camera to focus so the flash fires to light up the subject. I find it VERY annoying, and it totally blinds those who I am photographing. I'm not sure what to do about this either.

Anyone else have any suggestions?

[tim]

There's a custom function that turns that off on the 20D, but I forget exactly what it's called. Something to do with focus assist I think.

[Michaelmjc]

Rigby, I found that when you turn the autofocus off it doesn't do it. So I guess you will have to manual focus or give the people you're photographing a seizure.

[Anteros]

It's the autofocus assist light. You can disable it on the Rebel XT by setting custom function 5 to "Only emits ext. flash" or "Does not emit".

I find it very annoying too. While it does help with autofocus, the negatives of using the strobe far outweigh the positives in my opinion. You'd think that Canon would come up with a better way to do low light auto focus than a strobe. I disabled it and haven't looked back since.

I always hated taking portraits with my original Digital Rebel since you could not disable it on that camera.

[pjd83]

The camera wouldn't need to light up the scene for focus when its on manual.

When the camera is on autofocus and it doesn't have enough light for it to focus then it uses the flash to light the scene up to assist focus.

On manual, you'll be doing the focussing so the camera would not need to help you.

Its all the manual.

And its something that I think is very simple and makes lots of sense.

I don't have that trouble or need it dissabled.

In low light conditions I use an external flash with a built in focus assist beam.

[Curtis N]

In low light conditions I use an external flash with a built in focus assist beam.
That's the best solution.

With a camera as nice (and expensive) as the Rebel XT, a good flash attachment would be a great investment to expand the possibilities with that camera.

[jimsolt]

I was just outside taking some pics. I popped the flash up and went to take a picture, when the flash started goin off like a strob light. I almost had a seizure looking at it. It was on autofocus, and it doesn't seem to do it on manual focus... Anyone had that problem? Or know why it does that?

I think it's not a problem. It's the way the camera works. When you switch to manual focus, you change the way the camera works. It no longer needs enough light for auto focus to work. There are other ways to change how the camera works in low light situations, and still use the AF.
I just took my XT into a completely dark closet, flipped open the flash and took a picture. It did exactly as you said. My mode was AUTO (in addition to auto focus.)
I then in the same dark closet switched mode to AV (still in AF), flipped open the flash, took a picture,there was no strobing, the flash went off and end of story.
The difference: In AUTO mode, the camera reverts to what it considers ideal for flash pictures 1/60 at f/5.6. There is not enough light at that setting for the auto focus to work in the dark closet so the strobing you note provides enough light for the focus to work. When I switched to AV, my settings happened to be for a larger aperture, the camera treats flash in that mode as fill flash and I took a picture without the strobing.
Neither picture is very good -- yellow wall with some clothes hanging there, but they both appear to be of the same technical quality.
There are lots of different ways to change the ways these systems work. These cameras are pretty sophisticated. That's why they take good pictures. That's also why it takes a while to understand all the variables.
Jim