atik 428ex osc

[wahee]

hi

I have just purchased the 428 ex OSC camera

I have got it connected up and was looping shots with a cover over the nosepiece

I noticed this blue line in the image. It getts better when the camers is cooled, but I didn't think it should be there.

I tried a different USB port etc but no change
Any help most appreciated

[bwa]

I notice you're using a 1 sec exposure with AutoStretch checked.

1) Try a 1-5 minute exposure and see what the result looks like.

2) Then turn off AutoStretch and reset lower/upper bounds to min/max.  Capture the image and open it in something like Photoshop.  Stretch it and see if the problem still exists.

I have a mono 428Ex.  It has probably the cleanest dark frame I've ever seen.

bwa

[wahee]

hi thanks for the reply.

here is a 4 minute dark taken and stretched right up in PS. The issue seems to be much reduced in real world use I guess.

This one is with the cooling on

[bwa]

I believe the problem in your 1 sec sub was the huge stretch applied by the AutoStretch checkbox being checked.  The sub still looks a bit noisy with maybe more hot pixels than I would expect off a Sony sensor but I believe your image was one dark, not a stack of darks?

I've uploaded the 1800sec(30min) master dark off my mono 428Ex created from 20 subs taken at -10C for comparison (stretched to the max. w/ the Curves tool in Photoshop).  Image at:

http://tinyurl.com/bwa428Ex30minMstrDrk

I normally do not use darks in the processing of images off the 428Ex.  I do, however, dither subs to average out sensor "flaws", which are pretty minimal.

bwa

[wahee]

hi yes it was just one sub. The line is a bit concerning as it is continual.

The camera also was indoors at 26 deg C and the camera just would go down to -3 deg.

I will try to take a stack of darks at a lower temperature and compare

Your dark frame is amazing it shows just how great the camera can be

[bwa]

Yes, I've noticed you can only get about 30 degrees of cooling out of the 428Ex peltier; a problem if you're shooting in particularly warm climates. 

I have never run into this problem... it is -25C outside here at present.  Just in time to fire up my mount and get imaging!

bwa

[wahee]

yes it doesn't drop as low as some other cameras I have used.
It's a bit of  learning curve after using the DSLR for so long
I managed to get this shot of M42, so I think the camera is performing ok in real world use