Building a mult-camera rig - page 25 - Hotwire! Hardware Mods, Accessories and Insights - CHDK Forum

Building a mult-camera rig

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That's why you should interconnect each camera with its own 1K resistor.  That means they each see 1K when you pull all the other sides to ground.

i think there would be another potential problem - even this won't behave as expected if, for instance, you have 10 cameras connected but 5 of them are turned off. There will still be a path to ground through the resistors and through the circuitry of the switched off cameras, _even_ when your trigger is 'off',and this circuitry may be enough to bring the voltage below the threshold when you wanted it to be above.

 ie when a camera is powered down, is there a resistance between the battery terminal and ground and is it low enough to cause this issue.

 this problem could manifest itself as, you turn on the 1st camera out of 10 and the first camera sees an unintended trigger signal because you haven't turned on the others yet.

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That's why you should interconnect each camera with its own 1K resistor.  That means they each see 1K when you pull all the other sides to ground.

i think there would be another potential problem - even this won't behave as expected if, for instance, you have 10 cameras connected but 5 of them are turned off. There will still be a path to ground through the resistors and through the circuitry of the switched off cameras, _even_ when your trigger is 'off',and this circuitry may be enough to bring the voltage below the threshold when you wanted it to be above. ie when a camera is powered down, is there a resistance between the battery terminal and ground and is it low enough to cause this issue.
While this might be an issue, I doubt it. What you are talking about is a high impedance path backwards through the offline camera's power supply circuitry.  My suggestion here is "try it and see"  - you are not going to break anything.

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this problem could manifest itself as, you turn on the 1st camera out of 10 and the first camera sees an unintended trigger signal because you haven't turned on the others yet.
Regardless, none of the cameras are going to trigger just because they power on - unless maybe you are autostarting their multicam script.  But even then, so what?  One extra shot on your SD card that will just be ignored.
Ported :   A1200    SD940   G10    Powershot N    G16

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What you are talking about is a high impedance path backwards through the offline camera's power supply circuitry.
say it's a 100k impedance - is that reasonable? there'll surely be a resistor network across the output to monitor the feedback voltage. then with 10 cameras connected but not powered off, that would be like a 10k resistor in the circuit which you weren't expecting to be there - wouldn't that kind of value be significant?

 I've seen exactly this happen, not with the camera battery terminal / not depending on the camera power supply impedance, but I do have multiple triggers, deriving a 5v signal from the usb output of multiple raspberry pis, and any pi's that are connected but not turned on cause this issue, so I wanted to raise this.

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My suggestion here is "try it and see"  - you are not going to break anything.

agreed

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Regardless, none of the cameras are going to trigger just because they power on - unless maybe you are autostarting their multicam script. 

my thinking is, if the camera is set to monitor the battery terminal, then the 1st camera powered on will see a low signal on the battery terminal and so it will shoot, _if_ the mooted impedance and number of connected cameras does indeed cause a problem, of course. This would not need a script to be running for this to happen, if the menu setting is there?

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But even then, so what?  One extra shot on your SD card that will just be ignored.

 from my experience with multicam setups, the ideal, by far, is that the 1st pic across all the cameras is the same generation, the 9th pic is the same generation, and so on and anything else is potentially a major pain. I have almost 80 cameras now, i did a session of about 70 pictures, so we're talking over 5000 pictures to be sorted, I would definitely try to avoid anomalous photos as much as I can. Of course, other setups won't be so extreme, at the beginning anyway.

say it's a 100k impedance - is that reasonable? there'll surely be a resistor network across the output to monitor the feedback voltage. then with 10 cameras connected but not powered off, that would be like a 10k resistor in the circuit which you weren't expecting to be there - wouldn't that kind of value be significant?
Like I said, try it and see. If it's a problem, we'll figure out how to fix it. At this point, I'm certainly not going to invest any time playing "what if...".
Ported :   A1200    SD940   G10    Powershot N    G16


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Offline bismo

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Hi guys it's me again

I have another question but it's no longer about the remote function

Now it's about the bc:download function

For some reason I can't download the last picture, I've tried both the bc:download and the bc:download_last

These are the results

Code: [Select]
> exec bc=require('bcamHost') bc:download()
Connecting...
  1:Canon PowerShot A2500  = bus:\\.\libusb0-0001--0x04a9-0x3271 dev:bus-0 sn:430B11D876534109B0C5F4EC4C5368BD
ERROR: call failed:...ASUS\Documents\Bullet Time\chdkptp-r795\lua\bcamHost.lua:96: bad argument #1 to 'match' (string expected, got nil)
stack traceback:
...ASUS\Documents\Bullet Time\chdkptp-r795\lua\bcamHost.lua:96: in function 'camera_numbers'
...ASUS\Documents\Bullet Time\chdkptp-r795\lua\bcamHost.lua:285: in function 'download'
[string "bc=require('bcamHost') bc:download()"]:1: in main chunk
[C]: in function 'xpcall'
...sers\ASUS\Documents\Bullet Time\chdkptp-r795\lua\cli.lua:733: in function <...sers\ASUS\Documents\Bullet Time\chdkptp-r795\lua\cli.lua:724>
(...tail calls...)
[C]: in function 'xpcall'
...sers\ASUS\Documents\Bullet Time\chdkptp-r795\lua\cli.lua:285: in function 'execute'
...sers\ASUS\Documents\Bullet Time\chdkptp-r795\lua\cli.lua:400: in function 'run'
...sers\ASUS\Documents\Bullet Time\chdkptp-r795\lua\gui.lua:744: in function <...sers\ASUS\Documents\Bullet Time\chdkptp-r795\lua\gui.lua:744>

This is probably worth mentioning, so I cannot use the download command only when I use the remote cable, if I use the shoot command then it's no problem downloading

Thanks again

 

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