- This topic has 4 replies, 4 voices, and was last updated 2 years, 2 months ago by Grant Privett.
4 January 2021 at 11:45 am #574855John CoffinParticipant
Hi, I am using an old secondhand Lodestar, (not the X2) in the guiding module of my spectroscope. I need to identify star fields with it. This is sometimes difficult because of hot pixels which I haven’t been able to eliminate with dark frames or bad pixel maps. I am binning x2.
I am thinking of buying a new guide camera and wondered if anyone had experience of the Lodestar Pro. Would I be likely to notice much difference? I have read that the Lodestar cameras are prone to hot pixels.
Thanks, and Happy New Year.
John4 January 2021 at 5:17 pm #583648Callum PotterKeymaster
Hi John – happy new year to you too!
I recently purchased an Ultrastar Pro – which is an upgrade to the Ultrastar. I understand that the main changes with the Pro versions are to do with the electronics; faster downloads and lower read noise. And they now come in a blue body!
The Lodestar Pro uses the same CCD as the Lodestar X2 – but that is a different CCD to the original Lodestar. Whether this chip has fewer hot pixels I could not say… You could try emailing Starlight Xpress – they are usually helpful.
Callum4 January 2021 at 5:33 pm #583650John CoffinParticipant
Thanks Callum, I’ll try that. John4 January 2021 at 6:51 pm #583652Dr Paul LeylandParticipant
My Lodestar 2 works very nicely. Whether it has an abnormally large (or small, for that matter) I couldn’t say.9 January 2021 at 11:16 pm #583676Grant PrivettParticipant
Just a note to say that I have emailed you two images acquired with an old Lodestar and a recently purchased Lodestarx2.
As the cams are uncooled, I kept them in a cold room and then connected each in turn and took darks of 5x 5s duration with each at x1 binning. The noise does look better on the newer Lodestarx2.
I also took the 4th and 2nd frame of the Lodestar sequence and subtracted one from the other and measured the resulting difference image to determine its standard deviation, which was 32.7. Doing the same for the Lodestarx2 gave a standard deviation of 21.1.
I don’t know for a fact that the caps used to block light were equally opaque, but they were the same make. Similarly, the time the cameras had been turned on when each image sequence was taken, probably wasn’t identical. So the CCD may have been at a slightly different temperature as use warmed them up – but it would have been close, a matter of 10s difference at most.
Anyway, hope these are of interest. If anyone else wants copies of the images, then please let me know.
Do let us know what you find about the hotpixels. To me it looks like a factor of 2-3 decrease in the number of hotpixels in the Lodestarx2.
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