Pentax K100D with Sigma EF 430 ST PA flash?

[colinb23]

Does anyone know if this flash will work OK with my Pentax K100D? It has very few controls - OFF/TTL/MH/ML. MH clearly delivers more light than ML so I presume they stand for Manual High and Manual Low. Will the TTL system work even though there is no obvious way to change the ISO on the flashgun? Does it get that information directly from the camera? Does the camera control and cut off the flash or vice versa?
There is a screen on the back that lights up any one of these numbers - 28/35/50/70/80 - which looks like a zoom range. There is some communication with the camera because these numbers change as the lens is zoomed but not exactly to match. The flash fires properly - as the exposure is made - with TTL and it gives small flash just before the main flash goes off, presumably as way to reduce red-eye. It does not fire properly on MH or ML though that maybe because I have not set the camera correctly.
Unfortunately I do not have a manual and cannot locate one on line anywhere - well, I can but at a cost that is greater than my enthusiasm to pursue it that far! I just want to know if it can work well and how and if not - bye,bye,blackbird!
Any help appreciated, colinb23

[Mr Guy]

You need to worry about your trigger voltage. Mattdm usually swoops in and gives great answers on flash questions, so you might try sending a private message to him. As a general answer, you need to find out what the trigger voltage is in on that flash, because older flashes used higher voltages and can damage the most sensitive electronic components in modern DSLR.

[inkista]

No, it should be safe. The botzilla list has it around 10V-13V.

The MH/ML settings are for full and 1/16 power settings in lieu of your having full Manual control, if it's the same as the 530 DG. So you pretty much got the "High" and "Low" right.

And, as I understand it from what I've been googling up, it's a TTL-only flash, so yes the camera is supposed to be controlling the power output of the flash automatically. Whether it does the same "flavor" of TTL that Pentax is using on its digital bodies, though, could be the issue. If your exposures look good, the TTL is working. That "pre-flash" isn't for red-eye. It's for the TTL (through-the-lens metering). Basically, the camera tells the flash to send out a burst of a known brightness, and then meters it. Based on the metering, the camera can then adjust the flash's power output to be where it thinks it ought to sit (i.e., the "known brightness" part).

You may want to go and ask about this on a more Pentax-oriented board. The pentaxforums.com might be a good place to start, unless mattdm rides to the rescue.

[colinb23]

Thank you both for the responses. I did check out the likely trigger voltage before putting it on the camera, even though Pentax claim a very large voltage is safe, so I don't feel badly worried by that aspect. Well, a bit anxious, perhaps.
With TTL I guess that I need to at least preset either shutter speed or the aperture for the camera to be able to work out what to do? Without any guide factors on the flashgun I have no idea what to do in manual and I presume that in any full Program mode neither the camera or flash are going to communicate properly. It appears to work in TTL on the flash and Av on the camera in the few pictures I have taken round the house but is there a better way to confirm this?
With thanks, colinb23.

[inkista]

Originally Posted by colinb23

With TTL I guess that I need to at least preset either shutter speed or the aperture for the camera to be able to work out what to do?

I'd say yes. The camera will need to know the iso, aperture, (and if your flash can change the spread of the light, the focal length you're using) to figure out the best way to set power in TTL mode. It's hard to tell you what you need to do, though, since I'm unfamiliar with both your flash and your camera (which is why I suggested the Pentax forum, they'll at least know how your camera's supposed to work with this stuff).

On my Canon, if I'm in e-TTL mode, the flash and camera communicate all this information no matter what shooting mode my camera body is in. If, however, I'm using my Nikon SB-26 on the hotshoe (which cannot do any TTL communication), I can use the flash in "Auto" mode by setting the iso, aperture, and focal length directly via the flash back. It then spits back the effective flash distance to me on the LCD display. So, there are different ways this can be handled depending on the technology in both your camera and your flash.

Without any guide factors on the flashgun I have no idea what to do in manual and I presume that in any full Program mode neither the camera or flash are going to communicate properly. It appears to work in TTL on the flash and Av on the camera in the few pictures I have taken round the house but is there a better way to confirm this?

Not really.

I'd say just try the camera in Manual and set the flash to TTL mode. It should still work the same way as it did in Av, because the flash power is set via metering.

[colinb23]

Once more - thanks. I shall try some things as you suggest on a few settings and see what happens. If the results are less than good at least I shall know where I stand and can start hinting about the next Christmas or birthday present! My main worry was that I might damage the camera but the consensus seems that that is not very likely.
Grateful for your interest, cheers again, colinb23.

[JohnA]

Hi everyone. According to their website, Old Time Cameras can supply a manual for the Sigma EF 430 ST PA. - OTCWORLD -.
I hope this may help. I have no connect with OTC except as a satisfied customer.
JohnA.