Blessings, one quick question 2nd curtain flash. 20d

[johneric8]

I'm new to the 2nd curtain flash. I just enabled it on a 20d and I'm not sure if it's working or not? I can see that the flash is firing at the end of the exposure like it's suppose to but, for some reason it's still firing a flash as soon as the shutter button is pushed. So, basically with 2nd curtain flash enabled using the internal flash I'm getting two flashes. Is this normal? I guess I thought from what I read that when the camera was set to 2nd curtain it would only flash at the end of an exposure. As it stands right now I'm getting one at the front and back. I had the shutter speed set very slow so I could get a good view of what the flash was doing.. I would be very grateful for any answers one might have to give...

Blessings

[Ikinaa]

I got the same effect last time on the 20D with an exposure of 1 sec.
The first flash was not fired while the shutter was open, or I would have seen it on the pic.
My guess is that it's a preflash to measure the light (E-TTL), so that the cam knows how it has to fire the flash at the 2nd curtain.
Someone correct me please if I'm wrong.

[johneric8]

I got the same effect last time on the 20D with an exposure of 1 sec.
The first flash was not fired while the shutter was open, or I would have seen it on the pic.
My guess is that it's a preflash to measure the light (E-TTL), so that the cam knows how it has to fire the flash at the 2nd curtain.
Someone correct me please if I'm wrong.

thanks for your info!! I hope that more people out there give me their opinion on this.. I'm very curious....

[Andy_T]

I think that Gerard is exactly right.
Most likely its the preflash to determine the exposure.

An indication for this is if the first flash is not very powerful.

Or ... you might have red-eye reduction enabled (is there such thing on the 20D ??? )

Best regards,
Andy

[pierrot]

Nothing to add, you got your answer ;)

[Andy_T]

You could add a poll to it :twisted:

Best regards,
Andy

[Ikinaa]

You could add a poll to it :twisted:

Best regards,
Andy

Reminds me of a TV-Show ... 'Let's ask the audience...' (Publikumsjoker)

[robertwgross]

With normal first-curtain sync, you press the button, the pre-flash fires, that light is metered, and then the main flash fires very early during the shutter opening time. With second-curtain sync, you press the button, the pre-flash fires, that light is metered, then the shutter opening begins. Then late during the shutter time, the main flash fires.

That's the way it is supposed to be.

---Bob Gross---

[johneric8]

With normal first-curtain sync, you press the button, the pre-flash fires, that light is metered, and then the main flash fires very early during the shutter opening time. With second-curtain sync, you press the button, the pre-flash fires, that light is metered, then the shutter opening begins. Then late during the shutter time, the main flash fires.

That's the way it is supposed to be.

---Bob Gross---

Thansk so much Gentleman!! I was worried my camera was faulty!