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40 cameras - need help

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Offline ostiii

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40 cameras - need help
« on: 01 / June / 2013, 12:40:47 »
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Hi there,

I am an artist and I want to buy 40 cameras the same type. Quality is not so important. I want to shoot pictures at the same time with 40 cameras. How can I manage that. 2nd issue is that I want to transmit the pictures from the camera to a laptop (Mac or PC).
1. How can I realease 40 exposure the same time?
2. How can I transmit the photos from the cameras to a laptop? (without removing the cards)

Thanks so much - Laura
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Offline waterwingz

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Re: 40 cameras - need help
« Reply #1 on: 01 / June / 2013, 12:53:32 »
Its relatively easy to connect the USB ports of all camera in parrallel with a simple device like this :
http://www.gentles.ltd.uk/gentstereo/sdm.htm#repeat
and use the CHDK USB remote functionality to have them all shoot at the same time.

Unfortunately,  this does not provide communication capability for uploading pictures.

I suppose it would be possible to use powered USB hubs to connect all forty as USB devices and then use a script with chdkptp to shoot and then pull pictures from them all.   But I don't know what the limits are for USB devices and how that script would look.  Perhaps someone else will weigh in on that one.
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Offline adeuring

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Re: 40 cameras - need help
« Reply #2 on: 01 / June / 2013, 13:12:05 »
Quote from: waterwingz on 01 / June / 2013, 12:53:32
I suppose it would be possible to use powered USB hubs to connect all forty as USB devices and then use a script with chdkptp to shoot and then pull pictures from them all.   But I don't know what the limits are for USB devices and how that script would look.  Perhaps someone else will weigh in on that one.

According to http://en.wikipedia.org/wiki/Usb#System_design you can connect up to 127 devices to a single host controller (where hubs count as devices too).

I run tests for my Python/PTP/CHDK library regularily with four cameras connected to the dvelopmaent machine; I am sure that chdkptp would allow this too. Most cameras have a PTP property for their serial numbers, so you can also easily identify all 40 cameras.

How well "shooting at the same time" works will probably depend on the definition of "at the same time" ;) I would not be surprised if triggering all 40 cameras would need 0.1 or even 0.5 seconds.

Retrieving one photo from all 40 cameras will most likely need more than a minute if done sequentially. (Though using different threads or differnt programs and especially using more than one USB host connector would reduce the required time)
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Offline Microfunguy

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Re: 40 cameras - need help
« Reply #3 on: 01 / June / 2013, 13:35:29 »
Well, if you want to capture all the images within a lot less than a 1/1000 sec, there are people on the Yahoo SDM Group who can advise on suitable, often inexpensive, cameras and give you precise information for the synchronisation tests :-

http://tech.groups.yahoo.com/group/StereoDataMaker/

A number of members use multiple-camera rigs.
How important is retrieving the images immediately ?

I cannot really help you with that.
I would not want to get involved with the intracacies of PTP (a way of downloading images and movies from the camera using the USB connection) and I suggest that you also do not.

Just stick with capturing the images.


David
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Offline waterwingz

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Re: 40 cameras - need help
« Reply #4 on: 01 / June / 2013, 14:17:05 »
Quote from: Microfunguy on 01 / June / 2013, 13:35:29
I would not want to get involved with the intracacies of PTP (a way of downloading images and movies from the camera using the USB connection) and I suggest that you also do not.
This has come up enough times that I can't help but wonder if its been done. And probably more than once.

Sadly, once people get something working,  they often just get on with what they were trying to do in the first place and don't report back here.  Still,  CHDK supports all you need from a PTP perspective and chdkptp is easily scriptable.   Not exactly a shrink wrapped solution straight out of the box but also not rocket science (like gutting an S95 to make a "secret" instrument to stare into the beginning of time  :haha ).
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Offline ostiii

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Re: 40 cameras - need help
« Reply #5 on: 01 / June / 2013, 14:18:45 »
Hi all and thanks for your fast reply. I want to shoot my picture. Accuracy is not so important. I dont need to flash - there will be light the whole time. The download process can take a while (1-5 minutes) no problem.

Who can make me the scripts I need? I am an absolut beginner. Never hacked a camera before. Which camera will be best to buy?

Thank you so much

Laura
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Offline waterwingz

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Re: 40 cameras - need help
« Reply #6 on: 01 / June / 2013, 14:27:08 »
Quote from: ostiii on 01 / June / 2013, 14:18:45
Who can make me the scripts I need? I am an absolut beginner. Never hacked a camera before. Which camera will be best to buy?
I think the point that microfunguy was making is that this is not a simple project!   If you haven't worked with CHDK at all,  have no programming experience,  and limited computer experience, its going to take you a long time to get this working.  Even with lots of help from the good people here.

If you are still up for that,  we'll help.  But you need to go into this with your eyes open.
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Offline ostiii

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Re: 40 cameras - need help
« Reply #7 on: 01 / June / 2013, 14:38:26 »
OK - sounds like work. I love to work ;)

I´m not bad at computer work. So what will be the fuzzy part? Make the 40 cameras to work together? Or transmit all 40 pictures to the computer? What is the best way to start? Buy 10 cameras?

This is the way I understood it till now. I connect all cameras via USB-Hubs to one Computer. On this computer runs a script (that has to be written) to make the shot on all 40 cameras at the same time. And then there is a 2nd script to download the pictures from the camera.

Am I wrong?

Laura
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Offline Microfunguy

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Re: 40 cameras - need help
« Reply #8 on: 01 / June / 2013, 14:45:13 »
Quote from: waterwingz on 01 / June / 2013, 14:17:05
not rocket science (like gutting an S95 to make a "secret" instrument to stare into the beginning of time  :haha ).

S90 !
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Offline waterwingz

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Re: 40 cameras - need help
« Reply #9 on: 01 / June / 2013, 14:54:15 »
Quote from: ostiii on 01 / June / 2013, 14:38:26
OK - sounds like work. I love to work ;)
link> FLW  - the 2nd definition.

Quote
I´m not bad at computer work. So what will be the fuzzy part? Make the 40 cameras to work together? Or transmit all 40 pictures to the computer?
Most of the chdkptp work has been done with one camera / one computer.  So there is not a lot of support in the code for dealing with multiple cameras.   Although frankly,  once you need to deal with more than one,  two or forty are the same problem.

Quote
What is the best way to start? Buy 10 cameras?
Unless you have unlimited funds,  or find a bargain that you need to grab right away,  I'd suggest starting with two.  If you can make it work with two,  you can most likely make it work with forty.

Quote
This is the way I understood it till now. I connect all cameras via USB-Hubs to one Computer. On this computer runs a script (that has to be written) to make the shot on all 40 cameras at the same time. And then there is a 2nd script to download the pictures from the camera.
We seem to be off to a good start - nice summary.

Did I mention I love a fun project challenge?  When I started doing "blind ports" here there were a few comments. Now its common practice with a few people who have become a lot better at it than me.

Searching this forum is somewhat painful.  Give me an hour or two to see what's already out there?

Update : http://chdk.setepontos.com/index.php?topic=9097.msg94355#msg94355
« Last Edit: 01 / June / 2013, 15:10:04 by waterwingz »
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