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nie3mals
May 11, 2011, 10:20:52
Hello Folks,
i wanna capture a picture from 20 cameras at the same time.
now my question. is the bus system from the usb cameras enough fast, for trigger all cameras? or do you advise a hardware trigger with a ex. 5V impuls?

Thanks

Kevin

Stefan Geissler
May 11, 2011, 12:24:45
Hello Kevin,

I am very sorry, but I am not able to answer this question reliable. However, you can post 20 software trigger commands in sequence, but they are in sequence thus there is some time between the first and last trigger.
Also I see a little problem using 20 cameras: You must take care of the bandwidth each camera uses. You can not have 20 cameras sending at the same point of time images. Even running 4 cameras with 3.75 fps is near the edge of USB bandwidth.

nie3mals
May 11, 2011, 12:59:40
Dear Stafen
Thanks for your answere.
If I use the cameras only as image source (so i am only interessted on the picture, from each camera on the same time) and if a don`t use the video stream, is there always a problem with more than 4 cameras (up to 20 cameras)?

so you advise me, to use a hardware trigger, anyway?

regards,
kevin

Stefan Geissler
May 11, 2011, 13:04:35
Kevin

Keep in mind:
- The cameras have no memory. They stream the images through USB as soon as exposure has ended
- USB has limited bandwidth.


so you advise me, to use a hardware trigger, anyway?
Depends on the details of your job.