Apollo rover TV camera question...

[Trebor]

Quick question....
How was the exposure controlled on the camera, was it automatic or controlled from earth?

[ChrLz]

Not 100% sure, but according to:
http://www.hq.nasa.gov/alsj/GCTA-Manual.pdf
it did have an ALC (Automatic Light Control) function with both peak and averaging functions, and it appears to have been remotely operable.

[ka9q]

I'm pretty sure I saw the exposure level being manually changed, so i wasn't just an automatic gain control.

[dwight]

Yep it had both. There was a built in ALC (and the camera was rugggedly tested by pointing it at the sun) and Ed Fendell could control it from the ground.

[ka9q]

Tested by pointing at the sun? What changes were made to make that possible?

I was reminded of Apollo 12 almost every time I saw one of those videos taken from a shuttle SRB. They frequently captured the sun but weren't bothered at all.

[dwight]

On the Westinghouse Apollo 14 camera, there was a gauze filter placed over the scanning plate which dissipated the heat. For the GCTA, Sam Russel said it was one of the tests on the camera. They performed dust tests, vibration tests and bright light tests. The camera did have AGC as well and you can see it kick in whenever the camera pans over the sun. Somewhere I have the details, but in which document I have no idea as I never added the info into the comment field in my document database.