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CarlJF · 03-02-2016, 02:09 PM

One last thing that I could think of, I don't know if this setting exists on the 645D, but have you checked that red eyes reduction is off ? The delay from RER is quite obvious... Something like half a second...

petrakka · 03-02-2016, 02:33 PM

Originally posted by CarlJF

One last thing that I could think of, I don't know if this setting exists on the 645D, but have you checked that red eyes reduction is off ? The delay from RER is quite obvious... Something like half a second...

Haha, yep it does, but that's not the culprit. Actually, if you can believe it when I first got this thing and started messing with it there were 2 separate preflashes, and the red eye setting was on on the 645D. It was like a strobe party going off before the exposure ever happened.

Appreciate the troubleshooting help.

kp0c · 03-02-2016, 03:06 PM

Originally posted by petrakka

Thanks. Interestingly I have not had this problem with the SB-800 on a Nikon or the Nissin i40 on my Sony. Maybe it's that the Pentax preflash is much slower and I didn't notice it on the other cameras, not sure. But okay, so I am stuck with this. Good to know.

---------- Post added 03-02-16 at 01:10 PM ----------

Yea, this is what I have been doing, and it is fine. It just can kill the vibe/slow down the shoot some, which is why I want the TTL with no preflash. Basically the more shooting and less fiddling with other controls the happier I am.

---------- Post added 03-02-16 at 01:15 PM ----------

I've been fine doing this with other systems for awhile, it hasn't caused me trouble, but alright? I didn't ask for advice on how to shoot, which, if I did then cool, but I just asked if preflash could be disabled.

Isn't there an option on your slave lights to ignore pre flash? I'm pretty sure my yongnuo speedlights when set up in slave mode have an option to ignore pre flash, maybe your lights offer something similar. Not gonna help for the delay though.

Edit : oups - it has been mentioned already.

petrakka · 03-02-2016, 03:16 PM

Originally posted by kp0c

Isn't there an option on your slave lights to ignore pre flash? I'm pretty sure my yongnuo speedlights when set up in slave mode have an option to ignore pre flash, maybe your lights offer something similar. Not gonna help for the delay though.

Edit : oups - it has been mentioned already.

Yea, I use Profoto Acute B packs - I don't think there is this option. Will double check, but they are pretty featureless, besides a great quality and quantity of light haha.

Wildfire_ja · 03-02-2016, 07:04 PM

I have done that with a 360FGZ. In that setup I change the flash setting to "A". The flash uses its meter to determine correct exposure and you will have to tell it and fix your ISO and aperture, and working out exposure compensation gets a little tricky, but, upside is no preflash.

Scintilla · 03-02-2016, 10:10 PM - **1 Like**

Originally posted by Wildfire_ja

I have done that with a 360FGZ. In that setup I change the flash setting to "A". The flash uses its meter to determine correct exposure and you will have to tell it and fix your ISO and aperture, and working out exposure compensation gets a little tricky, but, upside is no preflash.

I mentioned this mode earlier in the thread, but the mark-II versions of the 360 and 540 (which is what the OP is using) don't have the A mode anymore.

beholder3 · 03-08-2016, 03:03 PM

Old used "auto" flashes with inbuilt automatic metering can be bought for $20 and less anywhere. Problem solved.

There are also very cheap optical slave thingies which can be used for cancelling out any pre-flash on studio flashes as they usually have two or more modes.

**clackers** · 03-08-2016, 06:08 PM

Originally posted by Wildfire_ja

I have done that with a 360FGZ. In that setup I change the flash setting to "A". The flash uses its meter to determine correct exposure and you will have to tell it and fix your ISO and aperture, and working out exposure compensation gets a little tricky, but, upside is no preflash.

You just lie about the ISO setting on the flash to get your EC.

awaldram · 03-10-2016, 07:03 AM

Originally posted by petrakka

Yea, I use Profoto Acute B packs - I don't think there is this option. Will double check, but they are pretty featureless, besides a great quality and quantity of light haha.

Not much use if that light isn't when the shutter opens !!

What I used to use was old exposed film over the sensor this reduces light level so the pre-flash is ignored but still fires on main flash.
Can be fiddly to initial setup but once working is reliable .

Haven't seen this 'issue' in many years as most flash modern equipment is fully aware of pre flash TTL and so has proper electronic cancellation.

What century are your studio flashes from

03-02-2016, 03:06 PM	#18
kp0c Veteran Member Join Date: Jan 2010 Location: Montreal Photos: Gallery Posts: 761	Originally posted by petrakka Thanks. Interestingly I have not had this problem with the SB-800 on a Nikon or the Nissin i40 on my Sony. Maybe it's that the Pentax preflash is much slower and I didn't notice it on the other cameras, not sure. But okay, so I am stuck with this. Good to know. ---------- Post added 03-02-16 at 01:10 PM ---------- Yea, this is what I have been doing, and it is fine. It just can kill the vibe/slow down the shoot some, which is why I want the TTL with no preflash. Basically the more shooting and less fiddling with other controls the happier I am. ---------- Post added 03-02-16 at 01:15 PM ---------- I've been fine doing this with other systems for awhile, it hasn't caused me trouble, but alright? I didn't ask for advice on how to shoot, which, if I did then cool, but I just asked if preflash could be disabled. Isn't there an option on your slave lights to ignore pre flash? I'm pretty sure my yongnuo speedlights when set up in slave mode have an option to ignore pre flash, maybe your lights offer something similar. Not gonna help for the delay though. Edit : oups - it has been mentioned already. Last edited by kp0c; 03-02-2016 at 03:11 PM.

03-02-2016, 07:04 PM	#20
Wildfire_ja Forum Member Join Date: Nov 2006 Location: Jamaica Posts: 62	Change the Mode I have done that with a 360FGZ. In that setup I change the flash setting to "A". The flash uses its meter to determine correct exposure and you will have to tell it and fix your ISO and aperture, and working out exposure compensation gets a little tricky, but, upside is no preflash.

03-08-2016, 06:08 PM	#23
clackers Otis Memorial Pentaxian Join Date: Jul 2013 Location: Melbourne Photos: Albums Posts: 16,397	Originally posted by Wildfire_ja I have done that with a 360FGZ. In that setup I change the flash setting to "A". The flash uses its meter to determine correct exposure and you will have to tell it and fix your ISO and aperture, and working out exposure compensation gets a little tricky, but, upside is no preflash. You just lie about the ISO setting on the flash to get your EC. Last edited by clackers; 03-08-2016 at 06:26 PM.

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03-02-2016, 02:09 PM	#16
CarlJF Veteran Member Join Date: Sep 2014 Location: Quebec City Posts: 1,185	One last thing that I could think of, I don't know if this setting exists on the 645D, but have you checked that red eyes reduction is off ? The delay from RER is quite obvious... Something like half a second...

03-02-2016, 02:33 PM	#17
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91 Original Poster	Originally posted by CarlJF One last thing that I could think of, I don't know if this setting exists on the 645D, but have you checked that red eyes reduction is off ? The delay from RER is quite obvious... Something like half a second... Haha, yep it does, but that's not the culprit. Actually, if you can believe it when I first got this thing and started messing with it there were 2 separate preflashes, and the red eye setting was on on the 645D. It was like a strobe party going off before the exposure ever happened. Appreciate the troubleshooting help.

03-02-2016, 03:16 PM	#19
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91 Original Poster	Originally posted by kp0c Isn't there an option on your slave lights to ignore pre flash? I'm pretty sure my yongnuo speedlights when set up in slave mode have an option to ignore pre flash, maybe your lights offer something similar. Not gonna help for the delay though. Edit : oups - it has been mentioned already. Yea, I use Profoto Acute B packs - I don't think there is this option. Will double check, but they are pretty featureless, besides a great quality and quantity of light haha.

03-02-2016, 10:10 PM - 1 Like	#21
Scintilla Veteran Member Join Date: Oct 2013 Photos: Gallery \| Albums Posts: 347	Originally posted by Wildfire_ja I have done that with a 360FGZ. In that setup I change the flash setting to "A". The flash uses its meter to determine correct exposure and you will have to tell it and fix your ISO and aperture, and working out exposure compensation gets a little tricky, but, upside is no preflash. I mentioned this mode earlier in the thread, but the mark-II versions of the 360 and 540 (which is what the OP is using) don't have the A mode anymore.

03-08-2016, 03:03 PM	#22
beholder3 Pentaxian Join Date: Dec 2011 Posts: 3,112	Old used "auto" flashes with inbuilt automatic metering can be bought for $20 and less anywhere. Problem solved. There are also very cheap optical slave thingies which can be used for cancelling out any pre-flash on studio flashes as they usually have two or more modes.

03-10-2016, 07:03 AM	#24
awaldram Veteran Member Join Date: May 2008 Location: Hampshire Photos: Gallery Posts: 732	Originally posted by petrakka Yea, I use Profoto Acute B packs - I don't think there is this option. Will double check, but they are pretty featureless, besides a great quality and quantity of light haha. Not much use if that light isn't when the shutter opens !! What I used to use was old exposed film over the sensor this reduces light level so the pre-flash is ignored but still fires on main flash. Can be fiddly to initial setup but once working is reliable . Haven't seen this 'issue' in many years as most flash modern equipment is fully aware of pre flash TTL and so has proper electronic cancellation. What century are your studio flashes from

P-TTL on AF540 GZII - Can you disable preflash?

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