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11-19-2010, 11:50 PM   #1
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Baby steps in flash - one photo fine, next black?

Hi guys, this is probably a really dumb question, but I am just starting out with a Sigma SuperDG 500, and I've been experimenting with off-camera flash, and seem to be having some trouble.

So, following the shockingly bad Sigma manual, I set everything up for off-camera flash using my pop-up as controller - so far so good.

I take a few photos at max sync speed (I believe 1/180 for this model), and this is where I get into trouble.

The remote flash is firing in every shot, but some of my shots are black - pitch black (I'm trying to get that black background look), and some of them are exposed correctly - i.e. the flash is lighting my subject up. But I can't figure out what the difference is. The flash is firing every time. Maybe I'm not waiting long enough between charges?

I've played with the two play-able settings on the flash in this configuration, an "f-stop" setting and a flash power setting, both of which move the metres/ft distance meter bar closer (e.g 1 metre) and further away (e.g 7 metres).

It seems like - even though the flash is firing in every shot - it's somehow only showing up in the picture when the slider bar is a metre or two in range of where the flash is actually positioned. But I don't understand why would be the case, at all. Furthermore, I seem unable to adjust the brightness/darkness of the flash by using the on-flash settings. It's always the same brightness, or so close my eyes and the photos are unable to tell the difference. I'm shooting in M, so it's not an issue with on-camera settings.

Is this because my focal length setting _on the flash_ is incorrect or something? How is it that despite the flash firing at the same time the shutter is up, I can only see the flash on certain photos? And how can I stop this happening?

As I say, this could be something really simple, but the manual is so bad, and I'm already confused. Any illumination (ha ha) my fellow pentaxians could supply would be most welcome. No doubt I've left out lots of pertinent info, but thanks for your time anyway.

11-20-2010, 07:35 AM   #2
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If some of the consecutive shots fail (too dark), your flash is not fully charged at the moment that the (underexposed) image is taken. Your eye might see the flash but I'm quite sure that you can't see the difference between the intensity of a fully charged flash and a not fully charged flash.

I suggest (for testing) to wait a longer time between consecutive shots and see if that solves the issue. I don't have experience with remote flashes so can not really advice further.

For further replies it might be useful to mention camera and lens used. The story might be very different between a DA18-55 and a M50/1.7
11-20-2010, 08:43 PM   #3
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Thanks sterretje I'll give that a shot!
11-20-2010, 08:57 PM   #4
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Are you using wireless PTTL? Or just slaving off the flash?

If you are using a non-PTTL flash to slave off the main flash, this could be your problem.
Pentax flash will send off a pre-flash to determine metering.
There is *NO* way to turn off pre-flashes on the current Pentax cameras.
A standard slave flash will fire on the pre-flash and not usually be capable of recharging by the time the main flash goes off. (sometimes timing catches the flash so results can appear intermittent and random)

If you are using PTTL, be sure the remote flash is set to PTTL slave and not "dumb" slave.

From what you describe, it sounds like behavior when the remote flash is slaving off the flash without any knowledge of PTTL signaling.

11-21-2010, 04:09 AM   #5
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Darn it, I still can't figure it out. What's confusing me is that it's working *sometimes*, and for the life of my I cannot find any rhyme or reason to why it works sometimes and not others.

Amoringello, I think you're right in that it might be a pre-flash issue - it's the only way to explain the complete blackness of my pictures, the flash is definitely firing and with my settings it should be easily showing.

Are there any Sigma Flash users out there?

I am

1) Setting it to P-ttl, slave, selecting the channel
2) Attaching the Sigma to my k-x, turning on k-x to M (1/180, iso200, f11) pressing the button halfway
3)Taking the Sigma off my k-x, positioning it (changing the focal and power level on flash doesn't seem to affect whether I capture it or no)
4) Popping my k-x flash (which is set to controller)
5) Manual focussing and pressing the button half, and then full, or just full
6) Blackness! Or occasionally the photo, but not very often, sob.

It doesn't matter if it's the first shot of a series, second, whatever. I can definitely confirm that the flash is both charged and firing.

There is something going on here that I am missing, but I can't figure out what, it's killing me! Does there look like an obvious missing step there to any Sigma users?
11-21-2010, 05:58 AM   #6
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I don't think you should be putting the Sigma on the camera in the first place.
The flash/came will be set up as the maser (or controller as set in K-r menus).
One would think everything should be reset dynamically, but who knows what level of QA was done and how the circuitry locks up or even shorts out as it crosses live pins! (probably good idea to not attach or disconnect the flash while the camera is on -- probably a even better idea to not do it while the camera is potentially actively communicating with the flash)

1. Set up your Sigma flash when you want it.
Be sure it is set in advance for using PTTL and correct channel. (I am assuming the flash has PTTL capability - it sounds like it does).
2. Set your M-r to use Wireless flash.
3. Pop up the on-camera flash. (Or have a second Sigma/Pentax flash in the hot shoe)
4. Fire.
11-21-2010, 11:03 AM   #7
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If your flash is indeed a Sigma EF-500 DG Super, it might need re-chipping by Sigma. That flash model had sync problem with Pentax cameras when used as a slave with the camera flash. The problem did not happen with the newer EF-530 DG Super. The re-chipping was made free by the Sigma importer/distributor, but I don't know if that still hold true, or if it was just for the original purchaser.
11-21-2010, 02:44 PM   #8
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A ha!! Thank Yves, so much - I bet that's it. I thought I was going crazy there!

11-22-2010, 07:46 AM   #9
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You're welcome. I hope it solves your problem.
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