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CHDK PTP multiple instances

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Re: CHDK PTP multiple instances
« Reply #90 on: 18 / November / 2013, 15:40:56 »
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Hey boys!

Just wanted to say I managed to switch two cams connected via PTP with an Arduino with remote sync enabled. I can even use the LiveView feature of CHDKPTP without switching it off before shooting, everything is reconnected as soon as the signal reapperas in the cable.

Now I have one question: To try snyching I turned on the flash of one cam while leaving the one of the other cam off. I was able to shoot with both cameras using the light from ONE flash only. But this is not reliable, sometime I got it, sometimes not.

Now I wonder what the reason might be? Is the revised synch-option part of the actual trunks? I altered the code as it was proposed here, but I don´t know if i have the high-recision-sync then.

Thanks! Martin...

Re: CHDK PTP multiple instances
« Reply #91 on: 18 / November / 2013, 19:55:25 »
Just wanted to say I managed to switch two cams connected via PTP with an Arduino with remote sync enabled. I can even use the LiveView feature of CHDKPTP without switching it off before shooting, everything is reconnected as soon as the signal reapperas in the cable.
Good to hear - the code I posted was really just a concept.

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Now I have one question: To try snyching I turned on the flash of one cam while leaving the one of the other cam off. I was able to shoot with both cameras using the light from ONE flash only. But this is not reliable, sometime I got it, sometimes not. Now I wonder what the reason might be? Is the revised synch-option part of the actual trunks? I altered the code as it was proposed here, but I don´t know if i have the high-recision-sync then.
The precision sync code proposed by vnd has not been added to the CHDK trunk.  I have a Arduino test rig built to test it on my cameras but finishing that project has not been a priority.
Ported :   A1200    SD940   G10    Powershot N    G16

Re: CHDK PTP multiple instances
« Reply #92 on: 18 / November / 2013, 20:56:24 »
I was able to shoot with both cameras using the light from ONE flash only. But this is not reliable, sometime I got it, sometimes not.
 I don´t know if i have the high-recision-sync then.

SDM does not support precision synch for most cameras for a very good reason  ..... it is not compatible with flash.

Unfortunately, some recent cameras need precision synch merely to give acceptable synch.
They do not support flash with or without precision synch.


Re: CHDK PTP multiple instances
« Reply #93 on: 18 / November / 2013, 23:04:12 »
SDM does not support precision synch for most cameras for a very good reason  ..... it is not compatible with flash.
To further explain,  both CHDK and SDM use the same precision sync mechanism and code. 

When shooting in sync mode, both programs wait until the last possible moment for the USB signal to go from 5V to 0V.  They then release the Canon code to complete the shot as quickly as possible.   The "quality" of the sync at that point is determined by how consistent the timing is between the release of the USB signal and the actual shutter release.   With recent cameras,  this tended to vary quite a bit - largely due to interference from the video sync code.  CHDK user vnd posted code to allow CHDK to compensate for this,  greatly improving sync.

Having said all that,  when you enable the flash on one camera,  you increase the time between when the USB signal goes to 0V and when the shutter fires. This results in one camera taking longer to shoot than the other and thus a sync mismatch.  Even if both cameras are enabled to "flash",  the timing between the two after the USB signal is released becomes more variable.  The vnd precision sync code does not (currently) correct for that - it never tried to.   So trying to sync using flash is problematic - both because the timing varies and because, in the rare case where the timing does not vary, the image will be overexposed by two flash units overlapping at once.

« Last Edit: 19 / November / 2013, 05:04:39 by waterwingz »
Ported :   A1200    SD940   G10    Powershot N    G16


Re: CHDK PTP multiple instances
« Reply #94 on: 19 / November / 2013, 05:12:35 »
Thanks for your posts. I have read thru the thread that discusses the synch efforts of vnd, all that is very promising, but the discussion stopped at the beginning of september. Why that?

And do you think the patch will become part of a official release?

However, I am not yet sure if I need that precise synch at all. I think for me being able to synch the cameras up to 1/1000th of a second is good enough for what I need. Did I get it right, that the "normal synched" CHDK version should give me maximum differences of about 40ms between the cameras? If so, it should be good enough for me.

Nevertheless I would like to test my new setup a bit, today I will build such an LED-board as waterwingz did. Hope I have some bright LEDs here. The tests I made yesterday where absolutely random, I did not even have the same settings on the cameras.

But before building the 50 channel version with its maybe 800 solder joints, I want to make sure the channels are build the right way, so I need a testing setup all in all.

Please, could some explain why activating the flashes makes the system vary more? Are there more tasks to be done between _wait_until_remote_button_is_released() and the actual shot?

Are there any other things I should consider to make the system more synched?

Thanks a lot!

Re: CHDK PTP multiple instances
« Reply #95 on: 19 / November / 2013, 06:35:32 »
maximum differences of about 40ms between the cameras? If so, it should be good enough for me.
Are there any other things I should consider to make the system more synched?

Surely you are contradicting yourself ?

Re: CHDK PTP multiple instances
« Reply #96 on: 19 / November / 2013, 08:04:14 »
Thanks for your posts. I have read thru the thread that discusses the synch efforts of vnd, all that is very promising, but the discussion stopped at the beginning of september. Why that?
As far as I can tell,  nobody was interested in pursuing it for CHDK (other than maybe me) and microfunguy took the code over to SDM for his users and stopped participating here.

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And do you think the patch will become part of a official release?
Probably some day when somebody wants to do a multi-cam rig and needs "CHDK only" features (like Lua) or is using cameras not supported by SDM.

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However, I am not yet sure if I need that precise synch at all. I think for me being able to synch the cameras up to 1/1000th of a second is good enough for what I need. Did I get it right, that the "normal synched" CHDK version should give me maximum differences of about 40ms between the cameras? If so, it should be good enough for me.
It depends on the camera model - you would need to test that.  But 40msec  (1/25 sec) is probably the worst you should see.

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Nevertheless I would like to test my new setup a bit, today I will build such an LED-board as waterwingz did. Hope I have some bright LEDs here. The tests I made yesterday where absolutely random, I did not even have the same settings on the cameras.
Let us know how that goes? I really need to get back to playing with mine now that I have some ultrabright LED's.

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Please, could some explain why activating the flashes makes the system vary more? Are there more tasks to be done between _wait_until_remote_button_is_released() and the actual shot?
Either more tasks or more code that takes a more random amount of time.

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Are there any other things I should consider to make the system more synched?
As you are using a custom build of CHDK in order to get USB remote sync and PTP to co-exist,  it should not be a big deal to build in vnd's precision sync patch.   But that still won't let you use flash on some cameras and not others.
Ported :   A1200    SD940   G10    Powershot N    G16

Re: CHDK PTP multiple instances
« Reply #97 on: 19 / November / 2013, 08:35:30 »
Surely you are contradicting yourself ?

Think so?

I don't. If there are any tasks I could do immediately without building a special CHDK version, examining registers and so on, why shouldn't I? It is a difference between disabling the OSD for example and hacking into CHDK, especially for me...

Also I don´t know which synch times my rig is capable of at the moment. It might also be I did not achieve my goal yet.


@waterwingz

I am a bit concerned doing the wrong things compiling my own chdk version. It was no problem to implement your single line, but when it comes to address registers I am hesitating.

40ms I consider to be 1/250th of a second, not 1/25th, no? 1/25th would absolutely not be acceptable, whereas 1/250th would be in most situations at least.

I never intended to use the inbuilt flashes of my cameras. I thought it would be a good way to test synchronization. As far as I can see for now, the images at least always get SOME light of the flash, I don't know the t0.5-specs of the inbuilt flash, and I suppose even Canon doesn't. But it seems at least that synch seems good enough that at least it is better than the time the flash needs to burn completely.

I still don't understand that thing with SDM. Is this a closed software? No source available? Looking at the SDM Homepage downloads I find ZIPs with the newest files from 2010, thus very old stuff. Looking here in the forum I find this: Microfunguy's Builds, where the last post is also ancient.

That´s the reason why I never considered SDM as an alternative. And if it is closed source I won't all in all. Could someone bring light into this? Thanks a lot...
« Last Edit: 19 / November / 2013, 08:39:50 by Karmaschinken »


Re: CHDK PTP multiple instances
« Reply #98 on: 19 / November / 2013, 11:30:55 »
I still don't understand that thing with SDM. Is this a closed software? No source available?
Could someone bring light into this?

I was not going to bother responding to Waterwingz comments but seeing as you ask  .....

Waterwingz has a tedious, long standing attitude-problem regarding SDM.
To use a recent phrase, he seeks "total domination of the Internet".
I normally just ignore it.

The situation is ........  SDM 1.86 Beta builds are available for testing via the ASSIST application.
I am in the process of preparing for official release.
That involves tidying-up the source code and writing new documentation.
That is a lot of work and as I do not devote my entire life to this it is not a priority  ..... especially as I have found 90% of testers are selfish and unreliable.
If they cannot commit time then neither can I.
I spent many enjoyable hours today taking photos rather than sitting in front of the PC.

That said, SDM 1.86 Beta does not include precision-synch code except for recent 'problem cameras'.
The degree of synch may sound impressive but why do you need it ?

CHDK will do what you want.

You can play games and programme with Lua.

Re: CHDK PTP multiple instances
« Reply #99 on: 19 / November / 2013, 12:19:34 »
Ah, okay, this is why I couldn't find any new release. I haven't been aware I could play games with CHDK too? I had a look at the menu, but could not find anything, where is that?  :)

Is SDM open source, too? I think CHDK is so advanced and stable because so many people are working on it, testing it.

All right, I have to work on my self-made synch-test-Arduino solution. I'll post some results here tonight...

Be nice and thanks a lot for all your help!

Martin...

 

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