How to control camera exposure?

[Alan 26]

I'm using a PCI-1428 board, a Pulnix TM-1020 camera, am programming in VC++, and I have unclear about controlling the "shutter" time and the gain control.

First, it looks like gain is controlled by setting the white-level voltage. Is this correct?

Next, I do not see how to set the shutter time. Is there a camera or session attribute that I am overlooking?

A possibly related aside: I have noticed that the camera seems to occasionally use different exposure or gain settings from those set in MAX when my application starts.

Thank you in advance for any guidance you may have.

Regards,
Alan

[cld]

Alan,
The Shutter timing is set by serial commands that are sent to the camera. With the current camera file for the 1020, the serial comands are listed int eh Shutter Control section, and are sent based on the user selection in MAX. There should be an attribute you can set in C for "Shutter Control."
With Digital cameras, gain is not applied by the board, but is a setting sent to the camera serially that tells it how to apply it to the data before digitizing it. Int he camera file, the default is set at 73, but can be varied from 0 to 255. Again this is set in MAX but should be changed with Set Attribute.
I hope htis helps.
Chris D
NI Applications Engineer

[Alan 26]

Dear Chris:

Thank you for your reply. I am able to implement the shutter and gain control as you indicate...and it has raised other questions.

It appears that the camera/board stops responding to the shutter/gain setting. This seems to happen after altering the settings a few (3-10) times. Altering the settings seems to occasionally halt the acquisition. Do you have any suggestions what the problem could be? It appears that the calls to SetCameraAttribute execute without errors.

I also find that I need to expose for longish periods--say 0.1 to 0.8 second. As this is longer than the available shutter times, how can I best do this?

Thank you again in advance for any help you may have.

Regards,
Alan