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05-28-2011, 01:40 AM   #16
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QuoteOriginally posted by Ash Quote
Yes, it seems to also drop to 3fps when something is mounted on the hotshoe, regardless of it being powered on or not.
Hmm, I just did some testing with my K-5 and don't get the same result. With either a Yongnuo YN560 or AF-540FGZ in the hotshoe and with the flashes turned off, the fps doesn't slow down.

With the AF-540FGZ in the hotshoe, turned on, and in M mode at 1/64th power, the fps does slow down and with every shutter actuation, the flash also fires.

With the Yongnuo YN560 in the hotshoe, turned on and in M mode at min power of 1/128th, the fps does not slow down, and the flash only fires every couple of shutter actuation, when it has recharged.

My theory on what is happening is that with pTTL flashes due to the communication between the flash and camera, the camera won't fire unless the flash is charged up and ready to go.

05-28-2011, 02:36 AM   #17
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QuoteOriginally posted by pop4 Quote
My theory on what is happening is that with pTTL flashes due to the communication between the flash and camera, the camera won't fire unless the flash is charged up and ready to go.
Still not making sense.
It's also happening when the flash is off, and regardless of whether the release while charging menu option is on or off.
05-28-2011, 03:00 AM   #18
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QuoteOriginally posted by Ash Quote
Still not making sense.
It's also happening when the flash is off, and regardless of whether the release while charging menu option is on or off.
Not for my K-5 (running firmware v1.03.22.11). Just quoting what I said earlier:
QuoteOriginally posted by pop4 Quote
Hmm, I just did some testing with my K-5 and don't get the same result. With either a Yongnuo YN560 or AF-540FGZ in the hotshoe and with the flashes turned off, the fps doesn't slow down.
And I'm pretty sure that the "release while charging" custom menu option refers to the built-in flash and isn't relevant to any external flash units.
05-28-2011, 03:13 AM   #19
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So just running the same test with my K-7:
- AF-540FGZ in the hotshoe, flash off. Hi-speed FPS stays at hi-speed
- AF-540FGZ in the hotshoe, flash on in M mode and at 1/64th. Hi-speed FPS stays at hi-speed and the AF-540FGZ actually keeps up with the FPS.

(My 2nd K-5 is with CK Kennedy, otherwise I'd run the test on it too, to see if the behaviour of a flash on it is the same)

And the mystery continues...

05-28-2011, 03:17 AM   #20
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Well all I can say is that I'm getting 3fps with the same firmware under the same conditions where you're getting the full 7fps...
05-28-2011, 04:21 AM   #21
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When you connect a dedicated flash to the hotshoe the camera detects the flash (whether the flash is turned on or not) as no Pentax flashgun can recharge and flash at more than 3 frames a second, and thats pushing it at higher powers, the camera slows it's framerate down to that.

You can get round it by using a 3rd party manual flash (the Yongnuo YN-560 is favourite, very fast re-cycle times) as these don't have the extra contacts the camera doesn't know it's there and does not switch the framerate down to 3 frames a second, but, no TTL, it's manual all the way.

This also works with radio triggers with the same Manual only limitation.

Chris
05-28-2011, 05:08 AM   #22
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Thanks for sharing this Chris.
That makes sense though as you can see in pop4's observation that with his AF540FGZ, which obviously has the contacts, his K-7 was able to maintain the hi-speed (5fps) shooting, on or off. Now the theory works for flashes that are on and communicating with the camera, but a flash that is off should not have any information being relayed to the camera.
05-28-2011, 06:22 AM   #23
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Yep, I tried it with Sigma ER-500 Super. Same results here.
Good Info Chris,, a big thanks..

05-28-2011, 07:49 AM   #24
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I just tried the same test on my K-7... also as on K-5 ONLY when the flash unit is ON it shots 3 frames per second.
when the flash is "off" and still attached to the hot-shoe the frame rate is as high on both models - K-5 & K-7.
I have noticed another thing : when flash is "on" but drained out of power after few shots, it is not firing because of recharging the capacitor. both models (k-5 & k-7) are firing in high frame rate until the flash recharges and become active.
05-28-2011, 12:14 PM   #25
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Could this 3 second rate be a part of the standard specification for PTTL. At some point with pttl development, someone probably sat down and figured out an exact sequence of preflash, flash recharge, focus times, flash lens zooming, red-eye pulsing, etc. and programmed the circuitry to those specifications. When pttl was designed, the shutter rate did not exceed 3 fps. When the new cameras have been brought out since the pttl development, there are probably sub-routines that are integrated in whole to avoid excessive labor in redesigning them.

Within pttl specification, there is probably also an integrated manual mode so thats why its (needlessly) affected also. While other camera mfrs have gone on to issue 2nd generation flash programming, Pentax is still using the old pttl code.

Bottom line - Pentax needs to come out with a new pttlREV2 and get some company to go build some flashes that will support it. One thought, perhaps the existing pentax flashes can support 7 fps, its only the camera programming that holds them back.

Meanwhile, i'm having a lot of fun with my Cactus radio triggers - didn't know they were such a good deal. Actually, i suspect any hot shoe radio trigger will not affect the frame rate because they are not flashes.

Last edited by philbaum; 05-28-2011 at 12:19 PM.
05-28-2011, 05:45 PM   #26
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QuoteOriginally posted by LEON Quote
I just tried the same test on my K-7... also as on K-5 ONLY when the flash unit is ON it shots 3 frames per second.
when the flash is "off" and still attached to the hot-shoe the frame rate is as high on both models - K-5 & K-7.
So that's the same as what I'm getting, but not what Ash is getting with is K-5...
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