ghosting from preflash?

I've noticed lately that some of my images, when using my 580exII, seem to have both the preflash, and the full flash, producing a bit of a ghost around the subjects.

Anyone know if this is normal or how i combat this?

I don't think you can have the pre-flash in the photo because I don't think the shutter is open when the pre-flash occurs. Probably what you are seeing is a mix of flash plus ambient light.

Are you on second curtain sync?

Can you post and example with exif?

I would suspect you are using Av and/or the shutter speed is too low.

Bearmann wrote in post #8215793
I don't think you can have the pre-flash in the photo because I don't think the shutter is open when the pre-flash occurs. Probably what you are seeing is a mix of flash plus ambient light.

^^ Right, the shutter is not open at the time of the preflash

Not during the main part of the preflash - the exposure testing and the slave flash setup - but does not the "Fire" instruction require that it is emitted by the master at the moment the shutter is open? I understand from Radiopopper's reading of the Canon patents that it does just that.

Aren't the ETTL control signals IR & shouldn't be visible (or have so little effect in relation to the main flash output)?

How are things Clive?

Often, this comes from relatively bright ambient light and camera or subject movement when the standard 1/60 sync speed is used, not from pre-flash.

Hi, Mark, and how are you? I miss meeting up with y'all.

An ST-E2 emits a "near-IR" signal, which can be a reason for using that device. However the 550EX, 580EX and 580EXII use the main flash tube, producing visible light. The power is low, but can have an effect in low-light conditions.

The effect is reproducable, if anyone wants to test it.

See post 9 in:
https://photography-on-the.net/forum/showthre​ad.php?t=715733

I used to think that the pre-flash never showed up in exposures until someone suggested that it did, and said to prove it by setting up two 580's in a master / slave config with the master flash turned off, then take a pic of both in a mirror.

I've not tried it but this poster said they did, and that both flashes showed up in the exposure.

That "someone" was me. And yes, they both (master and slave) are on in such a picture. See the link above.

Should I post a sample picture?

On the other hand, the OP never stated that he uses Canon's wireless system. If his gear list in the signature is true to the letter, he has only one 580 EX II.

Hmm... I think its b/c i was at 200mm, using 1/60th of a second, and that's too slow for 200mm...

that's what it is im sure... thanks alot guys!

If it matters or not depends on the strength of the ambient light, relative to the flash light.

apersson850 wrote in post #8217381
If it matters or not depends on the strength of the ambient light, relative to the flash light.

I agree and I have done the same. At slow shutter speed, with enough ambien light, the ghosting is caused by the camera shake or subject moving.

Dispite 1st or 2nd curtain sync, it will happen under the description above.

With a 200mm FL, a safe bet is to set TV mode at 1/200 or 1/250 shutter speed.

The curtain you sync with is totally irrelevant in that case, for sure.