550 EX flash question

Help...

I have the 10D with the 550EX flash. I know now how to set up for rear curtain sync, but the flash will fire at the beginning and at the end of the second curtain.

How do I get the flash to only fire once?

Thanks for the help....

Canon learning curve is difficult. It took me a hour to find the custom menu button on the EOS 3.

Loren "still wish Canon had a couple of nobs" Crannell

It's firing at the beginning because that's the preflash of the E-TTL system. The preflash is used to determine how much flash will actually be needed. The preflash won't show up in your photo.

This is one annoying thing about slow shutter people photography with Canon flashes. If you use FEL to make the preflash manually it'll save you the preflash when you actually take the photo.

Canon's E-TTL is the most unfriendly thing to learn of all Canon's products.

Top of the annoyances list of E-TTL is that you have to look at the back of the flash unit to know if there was enough light for a good exposure. With Nikon it tells you right in the view finder (Canon couldn't it that due to patent I believe)

Don't worry though. Once you learn the E-TTL system you'll find it just as useful as the Nikon's. I think it probably just takes longer to learn because it works less how people expect it to work.

Let me know if you have more questions about the flash. At one point I was fairly well versed.....details are getting sketchy now :)

Sorry, I forgot to actually answer your question. You can't turn preflash off unless you use the flash in manual mode.

I appreciate your quick answer. My first usage of the flash, and boy that was surprise with the rear sync. If I would've known, I probably would have gotten the Metz 54-4 which is designed for Canon digital, but the price tag was a little higher.

At least I know that I wasn't smoking cheap dope...

Thanks again Trevor...

Loren

Quote:

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Originally Posted by Trevor Ash

Sorry, I forgot to actually answer your question. You can't turn preflash off unless you use the flash in manual mode.

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Nope, you get the preflash anyway. The only way to avoid it it to tape a couple of contacts. At least with any of the later model Canon cameras. This is the only way I could get it to work with my studio strobes (which I gave up on doing after I found a used 283)

I'm not sure what you mean with the metz. Afaik, their canon version uses ttl too. BTW, what's wrong with the preflash? it is only at 1/60th power.

Mike

Quote:

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Originally Posted by darkman

Nope, you get the preflash anyway. The only way to avoid it it to tape a couple of contacts. At least with any of the later model Canon cameras. This is the only way I could get it to work with my studio strobes (which I gave up on doing after I found a used 283)

I'm not sure what you mean with the metz. Afaik, their canon version uses ttl too. BTW, what's wrong with the preflash? it is only at 1/60th power.

Mike

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The reason I don't like it is because flash can disrupt the subject while photographing them. For travel you people don't like flash, so instead of bombarding them with one flash per frame, you double it up. The same reason we all use flash meters in the studio, so we don't have to blind our subjects.

It's a small pick, but I really use rear-curtain sync a lot.

Loren

Quote:

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Originally Posted by darkman

Nope, you get the preflash anyway. The only way to avoid it it to tape a couple of contacts. At least with any of the later model Canon cameras. This is the only way I could get it to work with my studio strobes (which I gave up on doing after I found a used 283)

I'm not sure what you mean with the metz. Afaik, their canon version uses ttl too. BTW, what's wrong with the preflash? it is only at 1/60th power.

Mike

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Thanks for the correction. I'll have to go try again and see what happens with the 10D.

BTW, I also don't like the pre-flash for the same reason as Loren. For people photography it really confuses them. It's worse when you need to use FEL. For anything else thought it's not a problem.

Quote:

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Originally Posted by racingpinarello

The reason I don't like it is because flash can disrupt the subject while photographing them. For travel you people don't like flash, so instead of bombarding them with one flash per frame, you double it up. The same reason we all use flash meters in the studio, so we don't have to blind our subjects.

It's a small pick, but I really use rear-curtain sync a lot.

Loren

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Loren,

In general I'm not a big fan of on camera flash. My favorite use for it is for a natural looking fill (usually about -2/3 to -1ev with the camera in manual). As far as rear sync goes, I really only like it with action shots in low enough lighting conditions so that it makes a big streak. Otherwise I don't find it that interesting.

In most cases, except slow shutter speeds w/rear sync, the preflash to regular flash happens so fast nobody I know has noticed it. When I was figuring out which contacts to mask to stop it, I couldn't tell by eye, I just lit a subject with it and a studio light until it became overexposed. Then I knew the preflash didn't fire.

When I've bypassed it I only used it in manual mode. I'll have to give other modes a try. I also keep my studio fairly bright. After setting up I turn the modeling lights up, this avoids dialated pupils and, therefore, you get more of the color in their eyes. Another reason I don't like on camera flash.

I thought nikon equipment also uses a preflash?

Mike