Too tight of a zoom and image darkening when car passes through

[biggen]

Playing with my new 5241-Z12 I've noticed that if my zoom is too tight (>90% of maximum), a car moving into the scene will cause the image to quickly darken somewhat. White cars with sunlight hitting them really makes it happen on a cloudless day. As soon as the car moves out of the scene everything goes back to normal scene brightness as before the car moved into the frame. If I zoom out a ways its lessened to a large degree and if I'm zoomed out far enough its gone totally.

I assume its some type of auto Iris/Gain setting that is trying to adjust the image on the fly and a bright car with sunlight hitting it makes the camera think the image is overexposed. The issue is that it darkens it up so much for that split second that it dims the plate as well.

Just curious if anyone else has noticed this with tight zooms. I'm going to play with the gain range and instead of having it set for 0 - 50 have it set for 25 - 50 and see how that effects anything.

 

[wittaj]

I had that happen with setting a range on the shutter and too big of a spread on gain. I now run 1/2000 shutter and 30-35 gain and that eliminated it in my situation.

 

[biggen]

Yeah playing with the shutter range I upped the low end to .3ms and the high end to .5ms. That has tamed it quite a bit. I'll keep playing with it but it looks like that is the culprit.

You can run fixed 1/2000 shutter during the day?

Edit: Set the shutter to fixed 1/2000. So far I'm liking that better than range.

 

[wittaj]

Yes, I have been able to run 1/2000 shutter through all 4 seasons without an issue.