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08-22-2007, 06:43 AM   #1
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Wireless off camera flash - K10D

Hi all -

I have a question about using a flash unit off of the K10D. I recently bought a Promaster 7500DX flash unit for my K10D. The flash works great when connected to the camera, however, I have been trying to use the unit mounted on a tripod disconnected from the camera using the wireless option on both the K10D and the flash here is my setup...

- 7500DX is mounted on a tripod and set to trigger via the K10D on board flash
- The K10d is set to the wireless flash option

When I take the picture the 7500DX triggers but the picture is very under exposed. If I mount the flash on the camera, using the same aperture and shutter settings, the picture is perfect.

Has anyone used the wireless trigger of the K10D? It almost seems like the shutter is opening and closing BEFORE the 7500DX actually triggers.

Any ideas?

08-22-2007, 06:58 AM   #2
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How are you triggering the 7500DX? Could be the preflash setting it off if it's an optical slave you're using.
08-22-2007, 06:59 AM   #3
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I don't know the promaster but does it really have a true wireless option?
Perhaps it is just a slave option?
If this is the case the promaster is probably triggered by the TTL-preflash of the K10D.
08-22-2007, 07:00 AM   #4
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I am triggering the 7500DX with the on board K10D flash. Which I think is correct, but part of the issue is that I am not sure if I am setting the K10D up correctly.

08-22-2007, 07:06 AM   #5
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Don't use the K10D myself, but try setting a manual white balance. I believe this eliminates the preflash. This should at least allow you to rule out the preflash as a potential problem.
08-22-2007, 08:40 AM   #6
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QuoteOriginally posted by TMoore77 Quote
I am triggering the 7500DX with the on board K10D flash. Which I think is correct, but part of the issue is that I am not sure if I am setting the K10D up correctly.
I have no experience with the ProMaster, so can't help you there. But you ask about setting up the K10D. What I do with my K10D and my Pentax AF 540FGZ flash unit is pretty simple.

On the camera: Hit Fn, then the flash symbol (at 6 o'clock on the dial), then select "Wireless Mode" from the iconic listing of flash mode options. Wireless Mode's icon is a lightning bolt with a big "W" next to it -- it's the last option on the right.

On my Pentax 540 flash unit, there are three power settings: On, Off, and Wireless, which is in between on and off. I set the flash to wireless.

That's it. Well, of course I pop up the camera's built-in flash, since that's what triggers the external unit.

For what it's worth, I generally set the flash to P-TTL and set the camera to Av mode with auto ISO. If I have time to think while working, I use it and do things more deliberately. But if I don't have time to think, letting the the camera and flash do the thinking for me works pretty well most of the time -- and allows me to get the shots.

Will
08-22-2007, 08:48 AM   #7
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I omitted one thing, although it only affects how the wireless operation works, not whether it works or doesn't work.

Go to Menu > Custom Setting > Flash in Wireless Mode. It's the next to last item in the custom setttings list, so you can just hit the up button from the first item twice to get there quickly. Anyway, this setting determines whether the built-in flash contributes light to the shot (acts as a master) or whether it simply acts as a controller/trigger.

Will
08-22-2007, 10:09 AM   #8
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WMBP,

Thanks for the info. That is pretty much how I have been doing it EXCEPT for the "Flash in Wireless Mode" custom setting. Maybe that is my issue. I'll give it a try.

Thanks

08-22-2007, 02:11 PM   #9
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so did it work?
08-22-2007, 02:21 PM   #10
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QuoteOriginally posted by TMoore77 Quote
When I take the picture the 7500DX triggers but the picture is very under exposed. If I mount the flash on the camera, using the same aperture and shutter settings, the picture is perfect.

Has anyone used the wireless trigger of the K10D? It almost seems like the shutter is opening and closing BEFORE the 7500DX actually triggers.

May be that this is related to the wireless mode option in the custom settings menu, which I referred to earlier. It seems to me that, if the wireless mode is set to use the built-in flash simply as a controller, the built-in flash fires an instant BEFORE the shutter opens. That's not what you described, but perhaps it's what you were actually perceiving. In this mode, the light from the built-in flash simply triggers the other flash and does not contribute to the illumination of the subject. If you put the custom setting to the other option, where the built-in flash acts as a "master" and the other flash is a slave, then both units contribute to the illumination of the scene.

But if you have the other settings in the camera right and if you're using P-TTL, well, I am very much NOT an expert on flash, but it seems to me that the exposure should be close to correct in either case. The camera and the flash ought to know how much light is going to be thrown on the subject and should set the exposure accordingly. I will admit however that I do occasionally have an oddly underexposed shot that I can't easily explain.

One other thought. Have you checked to see if the flash unit is set to trailing curtain? Seems to me that it should not be (for normal shooting anyway).

Will
08-22-2007, 02:38 PM   #11
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So far, everything I have heard has indicated that the 7500DX is not a P-TTL flash, and so likely does not work with the Pentax wireless system. If it is P-TTL, there is still a good chance it does not work with the Pentax wireless system.

Most likely it is behaving as a normal optical slave, in which case the preflash is firing the big flash. Your symptom description sounds like this. WMBP's instructions won't work as they are for enabling wireless P-TTL, not dumb optical slaving.

Someone else commented that there are certain manual flash settings that disable the preflash - this is what you want to do. The other option is to buy RF wireless triggers such as Pocket Wizards ($$$$$$$$$$$$$$$$$$$$), Elinchrom Skyports ($$$$$$$$$$$), or the YinHe/Gadget Infinity "eBay triggers" ($30/set).
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