11x P&S Cameras Rig, little help needed? - page 2 - General Help and Assistance on using CHDK stable releases - CHDK Forum

11x P&S Cameras Rig, little help needed?

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11x P&S Cameras Rig, little help needed?
« Reply #10 on: 12 / January / 2016, 20:18:19 »
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Also as far as i understand, when running the multicam.lua "Stuff", to use it to take synchronized shoots with multiple cameras (like 11 in my case) i have to have 2 scripts- one type on the SD card in each camera and then the second type running from my PC through chdkptp, right?
There have been several solutions to this problem but AFAIK the multicam stuff from reyalp does not require anything specifically loaded on the camera. It can all run from the host PC as long as CHDK itself is loaded on the cameras.
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Offline reyalp

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Re: 11x P&S Cameras Rig, little help needed?
« Reply #11 on: 12 / January / 2016, 22:20:27 »
AFAIK the multicam stuff from reyalp does not require anything specifically loaded on the camera. It can all run from the host PC as long as CHDK itself is loaded on the cameras.
Correct, no additional scripts need to be installed on the camera.

There is camera side code, but it is sent and run by chdkptp as needed.
Don't forget what the H stands for.

Re: 11x P&S Cameras Rig, little help needed?
« Reply #12 on: 14 / January / 2016, 12:51:09 »
So i did some testing, and i shot using this command:
!return mc:testshots{tv=576,sv=411,nshots=1}
Which did synchronized shoots at f speed cca 1/60 and iso 100.

I used all my 10 cameras, pointed them at my PC screen and on my monitor i ran program called "Free Stopwatch" (http://download.cnet.com/Free-Stopwatch/3000-2350_4-75332299.html) and enlarge the screen to cover my almost entire monitor, it has format: hh:mm:ss:ms (hours:Minutes:seconds: and i believe miliseconds), so 00:00:00:01 = 10 miliseconds (i believe) and 00:00:00:99 = 990 Miliseconds

What was my suprise when i found out that in all 4 tests i run i got the same ms number on all my 10 cameras (pictures from them)... I was quite suprised... does this really mean that the shoots are so synchronized, that the difference is under 9 miliseconds... That almost seems too good to be true :-).

Is it possible or is my testing somehow flawed?

http://s21.postimg.org/5na4f6s5j/Super_Sync.jpg
(The picture above) i got the same picture (with the same time) from all my 10 different cameras, so it really seems that they all really fired in 00:02:48:46 (that means 46x miliseconds)... the difference had to been under 10 ms?

(I did the test 4 timea and almost get the same (identical) time in 1 test on all 10 cameras)
« Last Edit: 14 / January / 2016, 12:56:54 by goriskil »

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Offline reyalp

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Re: 11x P&S Cameras Rig, little help needed?
« Reply #13 on: 14 / January / 2016, 13:09:04 »
Is it possible or is my testing somehow flawed?
What is the refresh rate of your screen? That will dictate the maximum precision you can get with this method. 60 hz = 16 ms/frame.

Note if your exposure is 1/60th, the screen refreshing faster would make the numbers blur, because every exposure would include multiple values. Even at a 60hz, you'd expect some of the shots to be blurred, because they wouldn't synchronized with screen refresh.

There is also the question of how accurate the stopwatch program is. Do the numbers actually increment one digit at a time (subject to the limits of refresh rate), or do they have larger jumps.
Don't forget what the H stands for.


Re: 11x P&S Cameras Rig, little help needed?
« Reply #14 on: 14 / January / 2016, 13:23:11 »
If you have a CRT you should be able to download and test using "synctest011" e.g http://chdk.setepontos.com/index.php?topic=11667.msg118673#msg118673

I've only ever used with 2 cams so it might get a little crowsed with 10 cams?

Re: 11x P&S Cameras Rig, little help needed?
« Reply #15 on: 14 / January / 2016, 15:00:00 »
interesting... i dont have CRT anymore... and im not sure how precise is the stopwatch program (the numbers there simply move too quick :-).

I have 5 years old LCD monitor samsung t220 running at 1680*1050 22 inches screen... refresh rate i dont know... where can i find that :-D?

Re: 11x P&S Cameras Rig, little help needed?
« Reply #16 on: 14 / January / 2016, 15:16:16 »
Not relevant.

Edit: only for use with crt - I picked one up for £5:

I have this http://www.3dtv.at/Downloads/SyncTest011.zip as a bookmark and use mcafee.

Haven't used it in a while but will do again soon.
« Last Edit: 14 / January / 2016, 15:26:17 by andrew.stephens.754365 »

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Offline reyalp

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Re: 11x P&S Cameras Rig, little help needed?
« Reply #17 on: 14 / January / 2016, 15:39:06 »
I have 5 years old LCD monitor samsung t220 running at 1680*1050 22 inches screen... refresh rate i dont know... where can i find that :-D?
Windows display settings or something in the monitors own settings menu may tell you, but it's probably 60hz.
Don't forget what the H stands for.


Re: 11x P&S Cameras Rig, little help needed?
« Reply #18 on: 14 / January / 2016, 18:31:24 »
yeah probably 60hz, but still that means as you wrote 16 ms, thats still pretty small i believe:-).

Re: 11x P&S Cameras Rig, little help needed?
« Reply #19 on: 15 / January / 2016, 21:33:50 »
I shoot using the command:

!return mc:testshots{tv=384,sv=411,nshots=1}

is there a way to modify this command to specify to which distance from objective should the camera focus?

Or can i set the focus distance "for hard" in each cameras CHDK? and it would remember and work with remote shooting using CHDK ptp via command: !return mc:testshots{tv=384,sv=411,nshots=1}
?

thanks for help

 

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