Flash FPS query

Hi All,
Can anybody explain to me if i'm doing something wrong, or the camera/flash are not working properly.

I've tested the K-7 with both my 540 and 360. THey both work absolutely fine in all modes, including HS Sync.

Why does the fps rate dimish to about 1.5 per second when using flash?
I understand that the power (recycle time) might not keep up with the 5.2 fps the camera is capable of, but I have tested this both at HS (where the flash output is hugely dimished in Ptt-l) and in Manual mode, down to 1/64 or 1/32 of power (respectively on 540 and 360). The power should be low enough to have instant recycle times, so much so, that with fresh batteries you can test the flash continuously for many bursts one after the other (1/64th - pressing the test button)

Any ideas?

THank you (Matt )

Nathan

p.s. have you noticed that nikon flashes can fire at much higher fps speeds?

On my K20D there's a setting to prevent shutter activations before the flash is fully charged.

I don't know how quickly the camera logic determines flashgun charge state, etc, but maybe the K7 is waiting for confirmation of the charge state?

THank you John.

I have used and tried both custom settings. In the specific, I always use the 'allow shutter even when flash is not charged' setting.

But re-testing now, I can confirm that the speed is the same with both settings. This is because I am using the flash at its lowest possible power output, and therefore it recharges 'instantly'

THank you anyway

Have you asked Pentax, since I don't think anybody here has an answer for you.

Stefan, great suggestion.

Where do you think I should ask?

UK link
USA link
I should write them both.

ahhhh found a way!

If I set the flash off camera with cactus triggers - (which unfortunately only trigger up to 1/30 ... ) it does fire at 5.2 fps.

Now going to test 2 other off camera triggers - (cord and wireless)

Cool stuff...

edit - wireless can't work because the onboard flash can't be put down to very low power, and therefore takes ages to load....

and the Ptt-l cord trigger doesn't allow fast fps either.

I wonder what would happen with a proper radio trigger like the pocket wizards....

Just a note about HS mode... the output light power is reduced by 50%. However, the drain on the flash capacitor is still the same as in non HS mode

The reason is that in HS it has to rapid fire light to "pepper" the light as the curtains move. Not sure how many pulses occur in HS mode - maybe it's only two... one pulse for the upper half, and another pulse for the lower half. Hence the reduction in light.

Not sure about the FPS reduction... I'll try and find out what happens with the K20D sometime for you (wish I had a K7 to try ). It's probably down to the dedicated linkage between the body and flash.

Have you tried one of the old "dumb" PC style hotshoe adapters? Just make sure it's a plastic mount (so the dedicated pins of the AF540/360 aren't shorted out). You'd probably get "M" mode on the flash at 1/32 at full rate (because the camera won't know it actually a flash attached )

HTH!
Matt

If you put your flash on the K7, don't turn it on, and try to use continuous shooting, the FPS also drops to less than 4. I just can't figure out why. I guess it's a bug in the camera.

indeed, when I used the ebay triggers it fired at 5.2

btw just tried with the K10:
the fps rate is about half than the K7, so even without pushing too much, the idea is that the flash should cope with this rate.

Results;
If the K10 fires at, say, 2.8 / 3 fps, the AF540 oncamera, in M, 1/64, actually fires every shot. it may feel a tad slower than the normal fps rate, but only by a minimal amount, say 2.7 fps.

Interesting uh?

Yves,
there is a post on dpreview about this topic.
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=33129576&page=2


I have answered there as well; my K7 shoots at normal fps rate (5.2) when the flash is on the hotshoe but turned OFF.

You might have the same problem that the OP in that thread reports with his Metz 58.

This was the first (only?) problem I noticed with the pre-production camera, and mentioned it then, but have still yet to get an answer.

Chris has forwarded on my feedback to Pentax, so I guess it's just wait and see. Hopefully the bug will be fixed with a firmware update as you have proven that the flashgun is more than up to the task.

Metz 58 BTW

Indeed.

Very annoying!

I emailed Pentax UK when I wrote this post, but no reply from them.