> having problems with hot pixels. If I cool the camera down to -20c by
> placing it in the refrigerator, the dark frames show about half as many
> hot pixels as when the camera is only -10c. If this is normal, I was

oops sorry everything below is for my 416, but I still think
the point(s) hold.

My average dark pixel is around 3800 at -10C. A typical
PictorView contrast stretch shows "hot pixels" that are anywhere
from 4000 to 4500. I even found a couple at 6500. However,
I don't consider these to be "hot pixels" even though they show
as bright white spots on the dark. I don't have a complete
controlled experiment but maybe this data is useful:

A dark at -10C
average pixel 3800
possible hot pixel 386, 247 = 6320
possible hot pixel 121, 53 = 4365

A flat at 0C (and 9 months earlier, sorry)
average pixel 41000
possible hot pixel 386, 247 = 41658
possible hot pixel 121, 53 = 41133

As you can see the "hot pixels" in the dark frame are nicely
sensitive to light and have a good dynamic range. Since they
are consistent, they can be processed into good images.

In short Robert, you may not have a problem. I wouldn't attempt
tweaks to improve darks. Darks are done to improve the end product.

I would be interested in yours and other folks numbers, that way
I could discover just how wrong I am.

Jon B

View index by [date] [author] [subject]
Previous message: Re: [M]: [OT]: Opinions on flip mirror brands?, Gregg L. Ruppel
Next message: Re: [M]: PView 6.4 release 1 now available on Meade site, Jon Brewster
Next message in thread: Re: [M]: 216xt Temperature, R. A. Greiner
Previous message in thread: [M]: 216xt Temperature, Robert Exon