White dots on DSI preview image

[vic4loc]

I just bought a second hand Meade DSI II colour. Connected it to my PC, and with the cover on I can see various white dots & blue dots, with some blue lines, isnt it suppose to be completely black if I have the cover over it?

Strange enough, when I take it outside and focus on a star, I can see the star, with no white/blue dots, the background is completely black. However when I focus on a globular cluster, the white/blue dots reappear.

Have I been unlucky and bought a faulty DSI? or do i need to do some calibrations/adjustment to get rid of it?

Victor.

[Merlin66]

Victor,
Sounds pretty normal.
The coloured pixels are due to various issues - hot pixels which show a signal even when there's none, different sensitivities of the pixels etc etc
These can usually be suppressed by taking a series of DARK exposures (cover on) at the same exposure length (ie 10 sec etc) at the same temperature and then subtracting this DARK from the image.
HTH

[vic4loc]

Ok will try to take a few darks and see if the image processing will remove these. Still trying to learn this Meade DSI too :)

Was a bit worried I bought a dud DSI.

Victor.