K20D: Shutter lag paradox

I have made a device to trigger the shutter release when a laser beam is interrupted, and encountered a perplexing problem.

The accepted value for minimum shutter lag (i.e. in manual focus and exposure) seems to be about 0.09s.

Using a switch plugged into the remote shutter release port does not seem to make any difference as far as I can tell from simple observation.

But using my device plugged into the remote shutter release port produces delays of about 0.25s. I have tried both a relay and an optocoupler as the final stage in the device without major effect.

The device is not slow. Setting the camera to expose for several seconds and using the device to trigger a flash produces a more or less instantaneous result.

So where does the extra 0.16s come from? (Bear in mind the focus and exposure were set manually throughout.) If anyone (technically more competent than I) has a suggestion, I would be very grateful.

Thanks in advance.

John C

Assuming you are using a Pentax DSLR, did you have Shake Reduction turned on? Is it perhaps taking the extra time to stabilize?

Peter read the title, it's a K20D

And your point is...?

I hadn't considered shake reduction; I'll check it out. (Too many switches, too much automation, getting too old...)

Thanks, Peter.

John C

Nothing, just pointing Peter to where he can find the camera model John (the OP) is using.