Banding in Skies on Imacon scanner

[Chester McCheeserton]

Thanks Everyone. The negs were developed at a place that runs reframa dip and dunk - LTI in NYC. Kirk - I don't think it's in the processing as I flatbed scanned the negs first and the problem is not visible in those. (though I agree with your thought that good to make sure it's not that first) Also the banding moves when I flip the negative, which would seem to me to eliminate dust on the sensor.

Robert - your scratch on the prism thought seems the most likely to me, though it is a school's scanner, not mine, it's unlikely most of the students are as particular as me, (and none of them are scanning 5x7)
Could you get to/see the scratches on the prism yourself or did the folks diagnose that when you sent it in?

Dave -good to know about the belt - short side - my problem is always parallel to the long edge. I'll talk to the lab tech about the possibility of pulling of the side panels and doing some careful cleaning/dusting.

The only other variable is that I'm using an off market holder from China. and It's only an issue in smooth tone sky areas.

[interneg]

Thanks Everyone. The negs were developed at a place that runs reframa dip and dunk - LTI in NYC. Kirk - I don't think it's in the processing as I flatbed scanned the negs first and the problem is not visible in those. (though I agree with your thought that good to make sure it's not that first) Also the banding moves when I flip the negative, which would seem to me to eliminate dust on the sensor.

Robert - your scratch on the prism thought seems the most likely to me, though it is a school's scanner, not mine, it's unlikely most of the students are as particular as me, (and none of them are scanning 5x7)
Could you get to/see the scratches on the prism yourself or did the folks diagnose that when you sent it in?

Dave -good to know about the belt - short side - my problem is always parallel to the long edge. I'll talk to the lab tech about the possibility of pulling of the side panels and doing some careful cleaning/dusting.

The only other variable is that I'm using an off market holder from China. and It's only an issue in smooth tone sky areas.

How heavily used is the scanner - ie is it being run all day, every day?

Might be worth trying it first thing in the morning to eliminate the possibility that it's from the sensor getting too hot or similar.

When I experienced the problem, it was almost always at the end of a long day, rushing to squeeze a few extra scans in before going home.

I also wonder if it's possibly to do with the holder not being properly seated on the drawbar - given that they are magnetised, it's very easy to attach the holder off true & not notice. Have you checked to see if the firewire cable is securely seated at the back? I've seen far too many people get into a mess thanks to the cable either falling out, not properly seated etc.