istD AF-360fgz rear curtain sync

When I set my AF-360 to rear curtain sync, if fires a flash as
the curtain opens also, how can I stop this and why does it
do this?

Hi Kevin,

I assume you are talking about that pre-flash in your AF360FGZ. If I'm guessing right, worry no more. That pre-flash is part of the P-TTL feature and is NOT part of the actual exposure. It serves as a pre-reading for the metering to get the right amount of flash the next time it fires (actual flash).

My AF500FTZ does not have P-TTL (only TTL) and it doesn't behave the same way (pre-flash).


Regards.

That would make sense, but how can I change out of P-TTL mode into a mode where
it does not fire a pre-flash. All I can make it do is switch between P-TTL and SB

Kind regards
Kevin

Hi Kevin, I'm at work now while reading your post

Let me try to figure it out when I'm home, but if my memory serves me right, (and I think I read it somewhere) it will stick to P-TTL when used on *ist-D or MZ-S. But I may be wrong.

Any reason why you don't want it on P-TTL? IMO, the pre-flash could be distracting, but pre-flash and actual flash fires in a very rapid succession (almost instantaneously) unless you manually choose longer exposure and with rear-curtain sync.

Cheers.

I use the flash to trigger some studio flashes. This effectively gives me rear curtain sync
with the studio flashes, allowing me much control. The pre flash, of course, fires the
studio flashes. I need to stop this behaviour.

Kind regards
Kevin

Kevin,

I don't have the opportunity to try this out at the moment but...

P-TTL mode will only work when the camera has control of the aperture. On page 93, you see the AF360FGZ can be used in TTL mode - with a note 2: "When a lens used in position other than aperture A" (but remember you will also need to enable the custom function "F-stop other than A" otherwise the shutter will not fire).

Maybe, if you force the aperture with the thumb wheel, or better still, set aperture priority or manual, the P-TTL mode will automatically be disabled.

(If I get the chance, I'll try it out in the next few days and let you know).

Matt

Kevin,

An update... there's a workaround to get the "A" mode on the AF360FGZ, but I am not sure if rear curtain sync was properly enabled. Give it a try:

1. Power off the *istD and power up the AF360
2. Use the mode button on the AF360 to select "A"
3. Power up the *istD

As long as you don't touch the mode button, the AF360 stays in auto, and does not fire a pre-flash.

Let me know if this works
Matt

No, this does not work, just fires the flash without the rear curtain sync

Hi Kevin. The 360 will only offer P-TTL and SB when the camera is in Programme, Tv or Av. If you put the *ist into M mode, you should then be able to select the Auto and Manual flash modes. However, as soon as you put the flash into rear curtain sync mode, it goes into P-TTL mode. I don't think you can kill the preflash on the 360. I think you can probably, happily use the AF500 in TTL mode with rear curtain sync, without any preflash. perhaps you can borrow an AF500 to try this out.

I've spent half an hour hunting the *ist, the MZ-6 and the AF360FGZ manuals, and playing with the cameras/flash, and eventually decided you are in the proverbial. It won't work with the 360.

If you find out different, I'll be most interested, but I don't expect I'll need that feature for a while.

I have the ist with 360fgz flash and I understand the problem. For instance, you want to take a picture recording motion over a long exposure with the flash freezing the subject at the end of the exposure. Since the ist relies on the pre flash information in P-TTL mode to form the flash exposure we could assume that it may form an innacurate exposure because at the time of the preflash your subject has yet to reach the place in which it will be exposed by the flash... the preflash is firing at nothing and using that information to form the final exposure which includes your subject, im not certain what the effect will be probably overexposure on the part of the flash. I put the 360fgz on my MZ-60 whch works in normal TTL mode and this problem dissapears.

I've found a way to 'fool' the camera and 360 flash into shooting a rear curtain flash sync shot without a preflash using regular TTL. Thats a mouthfull and it makes me somewhat uncomfortable to think that I have to trick a sophisticated piece of technology to do what I want it to. Anyway this seems to work consistently, you start off with the sync switch on normal (green) then press your mode button to cycle to A or M manual flash. Now push the sync switch over to rear curtain and your next shot will be a rear curtain flash exposure that meters via regular TTL (you can see on the top left of the lcd 'TTL' where there would normally be 'P-TTL' in the duration of the exposure so I assume its gonnna work). Directly after this it will revert to P-TTL with preflash etc. I feel this is a limitation for however few photographers who want to use this technique. Having the feeling that the 360 fgz was not designed to do this but is easily capable of it. Disregard that if you're using any pentax that uses TTL flash metering.

Hi JimCracker,

Are you referring to the *ist-D camera?