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multicam: synch problems when using scripts

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Offline waterwingz

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Re: multicam: synch problems when using scripts
« Reply #20 on: 14 / July / 2012, 14:14:17 »
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Quote from: Microfunguy on 14 / July / 2012, 14:03:07
Less than one msec.
this is simply a value that stereo photographers find adequate for action shots, fast moving water, etc.
Thanks - that helps.

That S95 graph is much worse than I imagined it would be.  Your math is pretty much correct too - the likelyhood of getting 60 cams all within 1 mSec is pretty close to zero.
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Offline Microfunguy

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Re: multicam: synch problems when using scripts
« Reply #21 on: 14 / July / 2012, 14:58:50 »
The other problem is flash.

If this is for 3D modelling or similar, you need a single light source to avoid confusion.

If you must use flash, you would have to shoot at a relatively low speed, say 1/60 sec.
the gentLES switch will trigger an external flash.
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Offline Alarik

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Re: multicam: synch problems when using scripts
« Reply #22 on: 17 / July / 2012, 08:23:47 »
i made some tests with/without scripts
have a look to: http://chdk.setepontos.com/index.php?topic=8312.15
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Offline waterwingz

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Re: multicam: synch problems when using scripts
« Reply #23 on: 17 / July / 2012, 08:52:44 »
Quote from: Alarik on 17 / July / 2012, 08:23:47
i made some tests with/without scripts
have a look to: http://chdk.setepontos.com/index.php?topic=8312.15
FWIW ... I'm on record as saying there is no difference in how sync is handled internally by CHDK with or without scripts.  The sync function is not even in the same camera task as the script engine.  Your data shows a shift but I wonder if this is normal random variation or not ?
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Offline Alarik

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Re: multicam: synch problems when using scripts
« Reply #24 on: 17 / July / 2012, 08:59:06 »
maybe... I know 10 shots are not a very statistic result but I couldn't do more...
It could be as you say a normal random variation but I also see that in the
"no-script" test the bad shots are better than the bad shots "with-scripts",
there are never very dark shots... but, again, could be a random variation...
When it will possible I'll do other tests...
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Offline waterwingz

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Re: Re: multicam: synch problems when using scripts
« Reply #25 on: 17 / July / 2012, 09:45:40 »
Quote from: Alarik on 17 / July / 2012, 08:59:06
maybe... I know 10 shots are not a very statistic result but I couldn't do more...
It could be as you say a normal random variation but I also see that in the
"no-script" test the bad shots are better than the bad shots "with-scripts",
there are never very dark shots... but, again, could be a random variation...
When it will possible I'll do other tests...
Okay - I have a revised theory.  When running a script in ALT mode, there is an additional load on the CPU caused by the running of the script.  Based on my recent tests, this will increase the sync variability but I don't know by how much.  I think I can set up a test version that will run a script at a high yield factor and let the built-in USB remote code control the shutter if you would like to test this theory.
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Offline Alarik

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Re: multicam: synch problems when using scripts
« Reply #26 on: 17 / July / 2012, 09:48:25 »
Quote
I think I can set up a test version that will run a script at a high yield factor and let the built-in USB remote code control the shutter if you would like to test this theory.

Yes, please, I'll test it.
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Offline Alarik

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Re: multicam: synch problems when using scripts
« Reply #27 on: 20 / July / 2012, 06:14:53 »
Some other tests made with a much faster Flash: very good results.
100% synch at 1/60...

http://www.experience-3.com/PROJECTS/timefly/neorTest2.html
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Offline waterwingz

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Re: Re: multicam: synch problems when using scripts
« Reply #28 on: 20 / July / 2012, 10:19:30 »
Quote from: Alarik on 20 / July / 2012, 06:14:53
Some other tests made with a much faster Flash: very good results.

Would that not be expected as all you need is for all the shutters to be open when the flash goes? The short duration of the flash burst provides the sync.
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Offline Microfunguy

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Re: Re: multicam: synch problems when using scripts
« Reply #29 on: 20 / July / 2012, 12:59:04 »
Quote from: waterwingz on 20 / July / 2012, 10:19:30
Would that not be expected as all you need is for all the shutters to be open when the flash goes?

Yes.
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