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01-09-2014, 09:13 AM   #76
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QuoteOriginally posted by jhmos Quote
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
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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
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QuoteOriginally posted by Quicksand Quote
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
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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
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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
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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
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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
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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
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QuoteOriginally posted by tabl10s Quote
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
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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.
02-01-2014, 05:14 PM   #86
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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
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QuoteOriginally posted by kenyee Quote
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
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QuoteOriginally posted by tabl10s Quote
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
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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
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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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