Quote:
Originally Posted by EddieT
Hi Greg,
That's a good question...I wasn't aware of any issues with ghosting and the U9000 and I noticed nothing during processing. But there were some odd artifacts in the first hour or so of imaging on the first night. It looked like out-of-focus star reflections and existed in every image regardless of filter. They formed what looked like an asterism, however I could see no star pattern in the image that matched it. They disappeared after an hour and weren't there at all on the following night. It could have been dew spots that formed early and dissipated later, I'm not sure...But they were easily removed when combined with clean images...
|
Hi Eddie,
RBI (residual bulk image or ghost images) are an issue with the U9000 camera and any 09000 chiped camera. The 09000 chip seems more prone to it than others. I have read several complaints about it.
Apogee instituted an RBI fix which is an LED that flushes the chip
(saturates it then removes it) before your exposure. The ocst of this is a slight increase in noise. The camera has to be sent to Apogee for this to be fitted. New they come with it. FLI have had this feature for quite some time and pioneered it.
If you took a shot of the moon and then tried to take darks or continue imaging it would be very noticeable.
The pattern you mention could be RBI but it could be cosmic rays or even radiation from the CCD window radioactive breakdown (FLI camera, not sure about Apogee). These new chips are very sensitive and they often have squiggly little white spots in the darks that appear to be a bit random. They average out though when making your master dark.
I hope the new STX has this feature as a 09000 chipped camera without that feature would be somewhat of a liability judging by the complaints I have read.
I haven't seen any sign of it with the 16803 chip which whilst a tad less sensitive than the 09000 seems to be the enduring popular choice.
Greg.