Help Needed ! PTTL Mode doesn't turn on

[alantan]

G' Day,

I'm a Pentax K20D user and i kept having the same problem with my 540 flash.

When i mount my 540 flash to my camera , it does not read as P-TTL at all , i try to remove and install it again it still does not turn into P-TTL.....sometime this problem is quite frustrating as oddly as it can be, it keeps turning on and off..

this problem occur randomly as there are time i do not face the problem and the flash works alright.

how come i am not getting the consistant P-TTL..is there fault with the camera or the flash?

please help.

Regards,
Alan Tan

[spyglass]

Trying to understand your sceniaro (so excuse me if I have to ask the obvious), when you say "it does not read as P=TTL", do you mean that the display on the flash unit does not indicate that the flash is in P-TTL mode?
If you depress the Mode button on the back of the flash can you toggle through the various modes and get P-TTL to appear?
What lenses are you using when this happens. (DA, D FA, F, A, M) ?
What mode are you using on your K20D (Green, Program, AV, TV, etc)
What Flash setting are you using (accessed via the Function Button)
Have you tried using the Pentax Live Chat (see links on our Main Page - lower left hand column)



Spyglass

[calsan]

Make sure that the flash sync mode is set to leading curtain sync (ie to the far left position.)

It may depend upon the lens you are using - the manual says p-ttl mode is available when using DA, D FA, FA J, FA F or A lens.  I'm unsure if this rules out other brands, like Sigma or Tamron lenses.

Sorry if this was just stating the obvious, but hope that this helps anyway.

[calsan]

I've had the chance to play around with my 360 flash.  The first part of my answer doesn't make any difference with my setup.

Might still be the lens - although flash still works OK on p-ttl with my Sigma 10-20.

Are the contacts on the hot shoe clean?

[alantan]

Spyglass,

I'm using DA lenses. By instructions when i switch on my flash on my 540, i am able to trigger the flash in P-TTL mode but sometime its just stubborn and detect only at TTL mode. I've tried reseting by switching on/off both flash and camera and then remove the lens and lock it back...sometime this method works sometime not.

Does it means the problem lies in the flash? or else..

another troubleshoot to the problem is..sometime when its in a very good mood, it works the way i want it(which is how the manual book says so) but it get stubborn on the time when i need it most....happens during indoor events and the flash don;t work properly the way i wanted it..i'm quite frustrated.

just as i was checking it while typing..now its in P-TTL mode...at any sync options and its in A.Zoom mode but when i change the focal of my lens the zooming in the flash display did not detect it...

sighs...

help help

regards,
alan tan