Rear curtain sync flash with K-5/K-7

Hi all,

I'm having a bit of trouble getting rear curtain sync flash to work with my K-5 (I assume the K-7 works the same way).

Using the built-in flash it works fine (although I can't figure out how to avoid the pre-flash), but with an AF280T and an AF200S it will only fire once as the curtain opens. That's in all camera modes, and I've tried numerous combinations of flash settings.

Ultimately what I'm trying to do is get the flash to fire once, at the end of the exposure in bulb mode (preferably using the AF280T, although the AF200S would do as well).

Any ideas?

Many thanks,

Don

For rear curtain sync to work, your shutter speed must be below 1/180 sec, and you will always have a pre-flash. That's how P-TTL works. The longer the exposure, the more apparent the pre-flash.

Maybe you have "red eye reduction" on, which would give an extra burst of flash before the P-TTL pre-flash and flash.

Actually, the pre-flash for the P-TTL happens BEFORE the curtain opening, so it doesn't influence the picture itself.

AFAIK, for external units the rear curtain sync setting is set on the flash!

So, if you are trying to set it using the menu on the camera it won't work
The AF360/AF540 have a slide switch that chooses rear curtain (it basically chooses which edge of the trigger to fire on).

So, if your external flash doesn't support Rear Curtain Sync, then I'm afraid you won't be able to do it!

HTH!
Matt

Thanks for the info.

It doesn't make any sense though that it works at any speed in bulb mode with the built-in flash, but not with an external one.

Also, what's the point in pre-flash if I'm using manual metering as I am in bulb mode? Surely P-TTL doesn't apply in that case?

Ah, that would make more sense. If that's the case I might need to look at getting another flash...

...I wonder if you can trigger the pop-up with rear-curtain and a wired slave in leading curtain (or vice-vera)?

Might be interesting!

Just found out...

The external flash gun takes priority (at least on AF360).

i.e. Whatever the camera menu is set to, the pop-up flash follows the mode of a wired AF360. When the external flash is powered off, the camera menu then applies to the pop-up flash.


Just to also reiterate here, that the flash compensation on the camera menu sets the base compensation. The external flash compensation is applied to that base.
e.g. camera -1, flash 0 = -1 overall
e.g. camera -1, flash +1 = 0 overall

The pop-up flash is set to the camera compensation, so you can use camera -1, external flash +1 to get an overall 0Ev flash but the pop-up reduced by 1Ev. (hope that makes sense! )

Matt