Lodestar X2 Hot Pixels...

[PhotoGav]

My utterly reliable Starlight Xpress Lodestar X2 guide camera has decided to be unreliable... it has developed a couple of hot pixels that will not shift with darks or a bad pixel map in PHD2 - I redid both calibration frame sets yesterday evening, but nothing, they won’t go. Here are exhibits 1 & 2 that clearly show the annoying dots that lead to a flatline guide graph... both screenshots taken just now with the observatory roof closed, so it’s basically dark in there, with no stars...

 

 

Any ideas on what’s gone wrong here please?

[StarDodger]

They are probably not hot pixels but dead pixels, in which case nothing will calibrate them out...they will glow white in every image... it’s a shame, but not sure there is anything you can do..

[Davey-T]

My 2 Loadstars have a  few hot pixels, it's never bothered me as I know where they are and always manually select a guide star anyway, darks don't remove them.

I remember a lot of complaints on CN about them and some folk did have a lot, I've  got less than half a dozen.

Dave

[PhotoGav]

10 hours ago, StarDodger said:

They are probably not hot pixels but dead pixels, in which case nothing will calibrate them out...they will glow white in every image... it’s a shame, but not sure there is anything you can do..

Uh oh, that is not great, but sounds like a sensible answer. Damn!

8 hours ago, Davey-T said:

My 2 Loadstars have a  few hot pixels, it's never bothered me as I know where they are and always manually select a guide star anyway, darks don't remove them.

I remember a lot of complaints on CN about them and some folk did have a lot, I've  got less than half a dozen.

Dave

If I didn’t rely on PHD2’s auto-select guide star while I slumber, it wouldn’t be a major issue... but I do! Perhaps I will contact Starlight Xpress and see what they have to say about it.

[newbie alert]

I'm sure I've seen a hot pixel removal tool somewhere,  not sure on dead pixels

[Davey-T]

2 hours ago, PhotoGav said:

Uh oh, that is not great, but sounds like a sensible answer. Damn!

If I didn’t rely on PHD2’s auto-select guide star while I slumber, it wouldn’t be a major issue... but I do! Perhaps I will contact Starlight Xpress and see what they have to say about it.

IIRC they weren't particularly helpful and considered it normal though some folk with hot pixels in double figures got replacement I believe.

A search on CN might turn up the thread from the time, probably 3 years ago at least, time flies when you get old 

Dave

[StarDodger]

Hot pixels are a given with an uncooled CCD camera and are not an issue, my Lodestar gets loads, and is normal, it’s dead pixels that are more uncommon and that’s when you are more likely to get the camera changed, I doubt they would swap for hot pixels... !! 

[AngryDonkey]

Have you tried adding them manually to the bad pixel map? There is a function for this in PHD.

[PhotoGav]

Thank you for the various replies, that is all helpful stuff.

I have just been having a look at the various settings in PHD2 for the camera and have realised that rather than setting the binning to 2, I had only set the Noise Reduction to '2x2 mean'. When I set binning to 2, the image looks quite different and those two white blobs appear to disappear. I need to redo the BPM with the new settings and will report back!

[PhotoGav]

Well... I have just redone the calibration frames with the camera in Bin 2... and the two white dots appear to have vanished. Hurrah! I will see what happens under the stars... eventually!