External flash will not engage over 125/sec exposure

Hi all, I am so new to all this that you will have to excuse the lack of decent terminology.

I bought a Pentax K200 a few months ago and want to start portrait photography. I bought some lastolite flash heads and have attached to the hot shoe etc. Basically the external flashes will not fire when I set the exposure above 125/sec. I have pressed every available button and gone into the menu.

I do not want to set the flash heads off as slave to the on board flash.
Any suggestion will be great.

Ta

That's absolutely correct (you may find that 1/180s is your highest shutter speed).
It is down to the physics of the shutter that makes the limit.

All cameras have a shutter speed limit for external flash. Some other brands may go as high as 1/250s - but they all have a limit!

If you're having problems with the amount of light, then turn the light heads down until you get under 1/125s! Aim for around f/5.6 to f/11, and use the lowest ISO rating (ISO100 on the K200D?) Definitely use a fixed ISO - not Auto ISO (otherwise the camera will push up the ISO to handle the ambient light, not "knowing" that you've got huge flash heads to fill in the light!

HTH!
Matt