[miltona580]

Hello all,

I have recently started having problems with a Sigma EF-610 DG ST and my K-x. I have the following issues, which may be symptoms of one problem or multiple problems. I don't know, so I am coming here! I usually shoot in Apeture Priority mode.

1) The flash often will not zoom to the correct focal length.
2) The camera doesn't seem to be taking the flash's light output, leaving pictures way overexposed.

The only way I have found to solve the first issue is to turn the camera on after I turned the flash on. It used to not matter. The second issue I have found no solution for. I am quite confused and need some help. Thanks for reading!

[miltona580]

Oh one more important piece of information - the Sigma flash is for Pentax cameras, so it is supposed to talk P-TTL.

[sterretje]

I don't have this flash so can't really help.

The fact that it blasts full power indicates that it is not in pTTL mode. If the flash does not have an indication of the mode, you can check using the 2s delay: in pTTL it should give a pTTL pre-flash when you fully press the shutter and another flash 2 seconds later when the actual picture is taken.

Do the same exercise with the built-in flash. If the results are different, it indicates a camera / flash communication problem. If the results are the same (no pTTL), it indicates a camera or camera / lens communication 'problem'.

What lens do you use when this happens? Are you using M42/K/M lens when this happens? If so, pTTL does indeed not work (see page 162 of the camera manual).

Note:
FYI: The manual of a AF540 states to switch the flash on first and the camera next.

[miltona580]

Thank you, I will try that and report back.