I dont seem to able to guide on faint stars in AstroArt,only bright ones.
I heard somewhere that you have to take a dark frame before imaging,as this is then subtracted,
I dont know if this is right,
What is the correct procedure,so i can guide on faint stars.
cheers. mick

Hi Mick,

Yes, it helps to subtract a dark frame from the guider image. How that's done depends on your guider (whether it has a shutter or not).

Another thing that helps with dim stars is to bin the guide chip 2x2 or even 3x3. This concentrates the star-light on fewer pixels, helping improve the signal-to-noise ratio.

If you are using a separate guider, make sure that it's well focused. An out of focus star will also reduce S/N. A sensitive monochrome chip is best for an autoguider: color chips or other filters reduce the amount of light.

If you need any additional information, it may help if you describe your system in greater detail: what guide camera are you using, what guide-scope, etc.

Regards,

-Paul

Hi Paul.
I image using an 8inch SCT to which is attached an MX716 starlight camera.I use a 4inch guidescope,which sits atop the SCT.This scope has a MX516 attached,and i use star 2000 to guide with.
If i use the MX software i can guide on virtually any star within a 1sec image,and there is no problem.Its just i fine this software wanting.
In Astro-art,if i guide on a really bright star the crosswire is fine,and the background is nearly black.
Faint stars,the crosswire starts off ok,but it soon starts to wander,and the background is like a checkers board.The values start going haywire,and i have to abandon the image.I would have thought that Astro-art would have been more sensitive,but this does not seem to be the case.
Iwill try binning at 3x3 and see what this shows.
Thanks for the reply.
regards mick.

Hi Mick,

Dark frame is very important with your guiding setup, especially for dim guide stars. You'll need to cover up your guide scope to take it before starting to guide, but definitely use a dark frame to reduce guider images: amp glow and hot pixels can overwhelm a dim star very easily.

Binning can also help, although it sounds like you may not want to bin 3x3, as it will make stars too tiny on the gudie chip. See if binning 2x2 will improve your results.

Regards,

-Paul

Thanks for your help Paul.I will let you know how i get on.
regards. mick.