K-3 delay when using the flash

Unregistered User · 01-09-2014, 09:13 AM

Originally posted by jhmos

I just bought a cheap flash (Opteka EF790DG-P super) and have been trying it out. I found that in slave mode it discharges before the shutter opens unless the K3 flash mode is set to manual. I guess the camera must be doing some pre-flash in all modes except manual. If so, maybe we need an extra option to disable the pre-flash and eliminate the delay.

Put the in-camera flash on manual and there is no pre flash.

lister6520 · 01-09-2014, 12:24 PM

I had initially dismissed the delay as being trivial but I found it to be a real issue in practice. The delay may appear small but it is long enough to ruin action shots.
I tried shooting some bats as they flew up from behind a cliff a couple of days ago and was unable to catch any good pictures. I have previously managed to take such photos with the K-30 and the same Metz flash.

Switching to manual does solve the delay problem but is useless for such shots as the distance is very variable and unpredictable making manual settings unfeasible whereas P-TTL got quite good exposures almost every time, even when the bat presents a very small target for the exposure meter to measure.

There is something very odd about this:
The delay is not between the preflash and the main flash but between pressing the trigger and the pre-flash. I could possibly understand a delay between the preflash and main flash as being attributable to more complex processing of the data from the 86K exposure sensor but as it is the delay is at a time when the camera doesn't really have much to do. The delay between pre-flash and main flash is actually very short and about the same as on the K-30. I've checked this with an oscilloscope and also high speed video.
All three other Pentax cameras I have (one of which is a q-7) do not have any perceptible delay between pressing the trigger and the photo being taken.
I am hoping this is something Pentax will address in some not too distant firmware update - I am thinking it is just some trivial programming error as I can see no plausible reason for it, especially when one considers that earlier Pentax cameras dont have this poblem

**Heinrich Lohmann** · 01-09-2014, 01:18 PM

Originally posted by Quicksand

The pre-flash is a mandatory part of P-TTL. It won't work without it -- that's how the flash's contribution to exposure is evaluated so the necessary flash power can be calculated.

Unfortunately, that DOES mean third-party optical slave flashes won't work, except for ones that understand wireless P-TTL.

whenever I use optical slaves it is under very controlled conditions, (portrait or small groups) and everything is set to manual anyway. I have never used P-TTL with optical slaves.

Sienna · 01-10-2014, 10:03 PM

Another new Pentax user, with another K-3 exhibiting an unacceptable delay when trying to use the built in flash in P-TTL.
Yay for being Pentax Beta Testers!

sanjeevdas · 01-29-2014, 12:32 AM

Just got my new K3 and have the same issue. Both with the onboard flash and my 540 FGZ. Anyone found a solution yet?

jup · 01-29-2014, 01:20 AM

I mentioned this immediately when I got the camera - in comparison to my K-30 the flash feels prehistoric. It's like the camera has to think for a while before deciding to even fire pre-flash. I've spent quite a while playing with different settings but didn't find any combination that would change this behavior. I easily consider it biggest (and almost only) flaw of K-3. Which is really pity because otherwise the P-TTL is consistently spot on and works great with my old external Metz flash, which I certainly cannot say about K-30. For me, this is still a worthy trade-off since I rarely use flash, and if I do mostly for Macro, but I can easily see that for action flash shots K-3 is pretty useless. Here's just hoping they fix it in firmware. We should probably all loudly complain to Pentax.

gosman · 01-31-2014, 11:06 PM

So just found this thread and had my K-3 for 2 weeks. Would someone for my sake and other newbies, give a quick paragraph of what the general issue is and how we should test for it?

tabl10s · 02-01-2014, 12:14 AM

There's a delay between the time you press the shutter button and when the flash fires. The delay is actually multiple small flashes that does whatever is does before the flash fires a full power or any other setting you've chosen. It happened to me yesterday with the on-board flash and today with an external.

Since I don't use flash for sports, no problem. it would only bother me if I wanted to do something artistic as having the subject jump in the air.

kenyee · 02-01-2014, 12:51 PM

Originally posted by tabl10s

There's a delay between the time you press the shutter button and when the flash fires. The delay is actually multiple small flashes that does whatever is does before the flash fires a full power or any other setting you've chosen. It happened to me yesterday with the on-board flash and today with an external.

Since I don't use flash for sports, no problem. it would only bother me if I wanted to do something artistic as having the subject jump in the air.

From what I've read the issue is really a delay between shutter and preflash. So instead of:
shutter button -> preflash blink blink (1/4sec?) -> flash
you get
shutter button -> 1/2 sec delay -> preflash blink blank (1/4sec?) -> flash

The other alternative is to stop using the pTTL crutch and learn how to use your flash in manual or A modes...you might even find you like studio lighting like I do

Grokh · 02-01-2014, 04:30 PM

Yes, I have the same issue too. The delay is very short but very noticeable in comparison to both my K-5 and K-5IIs.

gosman · 02-01-2014, 05:14 PM

I'm not getting this on my internal or external flash. And if you do use manual external flash using pocket wizards, use the X mode! I found this out the hard way today during a lighting class!

tabl10s · 02-01-2014, 06:47 PM

Originally posted by kenyee

From what I've read the issue is really a delay between shutter and preflash. So instead of:
shutter button -> preflash blink blink (1/4sec?) -> flash
you get
shutter button -> 1/2 sec delay -> preflash blink blank (1/4sec?) -> flash

The other alternative is to stop using the pTTL crutch and learn how to use your flash in manual or A modes...you might even find you like studio lighting like I do

I actually like going manual and have done so since a friend traded his Sunpack 611 for my iron(!). I'm just glad Pentax fixed the overexposure problem and I'll be able to bounce shots on the fly.

lister6520 · 02-02-2014, 05:41 AM

Originally posted by tabl10s

I actually like going manual and have done so since a friend traded his Sunpack 611 for my iron(!). I'm just glad Pentax fixed the overexposure problem and I'll be able to bounce shots on the fly.

Its not always a matter of choice whether to go manual or P-TTL - sometimes P-TTL is the only way a shot can be taken, especially action shots which are not staged.

tabl10s · 02-02-2014, 06:35 AM

Unfortunately, I can't use flash when I shoot Table Tennis which is the only sport I do. P-TTL would be fantastic.

gosman · 02-03-2014, 08:14 AM

Just tried my on board flash again. Shot about 5 times -no hesitation. This seems to be a non issue with maybe a few early models exhibiting the delay.

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01-09-2014, 09:13 AM	#76
Unregistered User Guest	Originally posted by jhmos I just bought a cheap flash (Opteka EF790DG-P super) and have been trying it out. I found that in slave mode it discharges before the shutter opens unless the K3 flash mode is set to manual. I guess the camera must be doing some pre-flash in all modes except manual. If so, maybe we need an extra option to disable the pre-flash and eliminate the delay. Put the in-camera flash on manual and there is no pre flash.

01-09-2014, 12:24 PM	#77
lister6520 Veteran Member Join Date: May 2012 Posts: 733	I had initially dismissed the delay as being trivial but I found it to be a real issue in practice. The delay may appear small but it is long enough to ruin action shots. I tried shooting some bats as they flew up from behind a cliff a couple of days ago and was unable to catch any good pictures. I have previously managed to take such photos with the K-30 and the same Metz flash. Switching to manual does solve the delay problem but is useless for such shots as the distance is very variable and unpredictable making manual settings unfeasible whereas P-TTL got quite good exposures almost every time, even when the bat presents a very small target for the exposure meter to measure. There is something very odd about this: The delay is not between the preflash and the main flash but between pressing the trigger and the pre-flash. I could possibly understand a delay between the preflash and main flash as being attributable to more complex processing of the data from the 86K exposure sensor but as it is the delay is at a time when the camera doesn't really have much to do. The delay between pre-flash and main flash is actually very short and about the same as on the K-30. I've checked this with an oscilloscope and also high speed video. All three other Pentax cameras I have (one of which is a q-7) do not have any perceptible delay between pressing the trigger and the photo being taken. I am hoping this is something Pentax will address in some not too distant firmware update - I am thinking it is just some trivial programming error as I can see no plausible reason for it, especially when one considers that earlier Pentax cameras dont have this poblem

01-09-2014, 01:18 PM	#78
Heinrich Lohmann Site Supporter Join Date: Sep 2006 Location: Airdrie, Alberta Canada Photos: Gallery Posts: 8,097	Originally posted by Quicksand The pre-flash is a mandatory part of P-TTL. It won't work without it -- that's how the flash's contribution to exposure is evaluated so the necessary flash power can be calculated. Unfortunately, that DOES mean third-party optical slave flashes won't work, except for ones that understand wireless P-TTL. whenever I use optical slaves it is under very controlled conditions, (portrait or small groups) and everything is set to manual anyway. I have never used P-TTL with optical slaves.

01-10-2014, 10:03 PM	#79
Sienna New Member Join Date: Jan 2014 Posts: 6	Another new Pentax user, with another K-3 exhibiting an unacceptable delay when trying to use the built in flash in P-TTL. Yay for being Pentax Beta Testers!

01-29-2014, 12:32 AM	#80
sanjeevdas Senior Member Join Date: May 2012 Location: San Jose, CA Posts: 111	Just got my new K3 and have the same issue. Both with the onboard flash and my 540 FGZ. Anyone found a solution yet?

01-29-2014, 01:20 AM	#81
jup Senior Member Join Date: Nov 2009 Location: San Jose, CA Posts: 103	I mentioned this immediately when I got the camera - in comparison to my K-30 the flash feels prehistoric. It's like the camera has to think for a while before deciding to even fire pre-flash. I've spent quite a while playing with different settings but didn't find any combination that would change this behavior. I easily consider it biggest (and almost only) flaw of K-3. Which is really pity because otherwise the P-TTL is consistently spot on and works great with my old external Metz flash, which I certainly cannot say about K-30. For me, this is still a worthy trade-off since I rarely use flash, and if I do mostly for Macro, but I can easily see that for action flash shots K-3 is pretty useless. Here's just hoping they fix it in firmware. We should probably all loudly complain to Pentax.

01-31-2014, 11:06 PM	#82
gosman Senior Member Join Date: Jan 2014 Location: Texas Posts: 263	So just found this thread and had my K-3 for 2 weeks. Would someone for my sake and other newbies, give a quick paragraph of what the general issue is and how we should test for it?

02-01-2014, 12:14 AM	#83
tabl10s Veteran Member Join Date: Jun 2011 Location: Sacramento(formerly from B'Ham, England). Posts: 1,424	There's a delay between the time you press the shutter button and when the flash fires. The delay is actually multiple small flashes that does whatever is does before the flash fires a full power or any other setting you've chosen. It happened to me yesterday with the on-board flash and today with an external. Since I don't use flash for sports, no problem. it would only bother me if I wanted to do something artistic as having the subject jump in the air.

02-01-2014, 12:51 PM	#84
kenyee Veteran Member Join Date: Mar 2007 Location: Boston, PRofMA Photos: Albums Posts: 3,026	Originally posted by tabl10s There's a delay between the time you press the shutter button and when the flash fires. The delay is actually multiple small flashes that does whatever is does before the flash fires a full power or any other setting you've chosen. It happened to me yesterday with the on-board flash and today with an external. Since I don't use flash for sports, no problem. it would only bother me if I wanted to do something artistic as having the subject jump in the air. From what I've read the issue is really a delay between shutter and preflash. So instead of: shutter button -> preflash blink blink (1/4sec?) -> flash you get shutter button -> 1/2 sec delay -> preflash blink blank (1/4sec?) -> flash The other alternative is to stop using the pTTL crutch and learn how to use your flash in manual or A modes...you might even find you like studio lighting like I do

02-01-2014, 04:30 PM	#85
Grokh Senior Member Join Date: Feb 2011 Location: St.-Petersburg Photos: Albums Posts: 267	Yes, I have the same issue too. The delay is very short but very noticeable in comparison to both my K-5 and K-5IIs.

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02-01-2014, 05:14 PM	#86
gosman Senior Member Join Date: Jan 2014 Location: Texas Posts: 263	I'm not getting this on my internal or external flash. And if you do use manual external flash using pocket wizards, use the X mode! I found this out the hard way today during a lighting class!

02-01-2014, 06:47 PM	#87
tabl10s Veteran Member Join Date: Jun 2011 Location: Sacramento(formerly from B'Ham, England). Posts: 1,424	Originally posted by kenyee From what I've read the issue is really a delay between shutter and preflash. So instead of: shutter button -> preflash blink blink (1/4sec?) -> flash you get shutter button -> 1/2 sec delay -> preflash blink blank (1/4sec?) -> flash The other alternative is to stop using the pTTL crutch and learn how to use your flash in manual or A modes...you might even find you like studio lighting like I do I actually like going manual and have done so since a friend traded his Sunpack 611 for my iron(!). I'm just glad Pentax fixed the overexposure problem and I'll be able to bounce shots on the fly.

02-02-2014, 05:41 AM	#88
lister6520 Veteran Member Join Date: May 2012 Posts: 733	Originally posted by tabl10s I actually like going manual and have done so since a friend traded his Sunpack 611 for my iron(!). I'm just glad Pentax fixed the overexposure problem and I'll be able to bounce shots on the fly. Its not always a matter of choice whether to go manual or P-TTL - sometimes P-TTL is the only way a shot can be taken, especially action shots which are not staged.

02-02-2014, 06:35 AM	#89
tabl10s Veteran Member Join Date: Jun 2011 Location: Sacramento(formerly from B'Ham, England). Posts: 1,424	Unfortunately, I can't use flash when I shoot Table Tennis which is the only sport I do. P-TTL would be fantastic.

02-03-2014, 08:14 AM	#90
gosman Senior Member Join Date: Jan 2014 Location: Texas Posts: 263	Just tried my on board flash again. Shot about 5 times -no hesitation. This seems to be a non issue with maybe a few early models exhibiting the delay.