How do I turn off the pre flash?

I want o use some old optical triggers on some flashes..
How can I turn off the pTL/ pre-flash?

Rune,

Har ingen aning! Have no idea!

Just ordered a K-30 for the wife (returning to Pentax, here we go!)!

Welcome back ... and what color ?!

Blue, of course! Like my K-x, but it is not as subdued as the K-x's color! And a DA70 is on order ;-)!

My D600 is visiting the Nikon doctor, for similar oil problems as the K-5s had (and many other cameras has had similar problems, not least from Canon).

Rune,

I had the same problem and struggled to find a solution other than using a cheap external flash on-camera as the trigger for the optical slaves. I’d bounce it from the ceiling at low power so that it only had a minimal effect on the image but triggered the slaves.

Now I use Cactus v5 wireless triggers, these make the whole setup much easier. They are not as good as Pocket Wizards but are so much cheaper and so far have been 100% reliable.

Hope this helps.