SharpCap Forums

I have taken an image of the Soul Nebula which contains 32x5 minute sub frames. If you look at the main image all looks fine but if I zoom in to I see what are like hot pixel trails which is on the other attached image. There are no apparent star trails and the nebule gas looks uniform.
Any idea what those trails are?

Hi,

yes, that's what they look like to me too. The first step with these sort of trails is to use dark subtraction *and* hot/cold pixel removal, but I guess you may already be doing that....

You could try turning up the 'hot/cold pixel sensitivity' to see if that helps, or check your dark frame as unusually dim pixels in the dark can cause bright pixels after subtraction. If all of that is already done then dithering is probably the next step - it doesn't get rid of the slightly hot pixels, but it spreads the bright points around and makes them much less noticeable than the sort of lines you are seeing here.

Hope this helps,

Robin

Hi Robin,
Thanks for the reply. I use dark frames to match the length of time capture I am doing but I haven't yet (which I will do next time) adjusted the hot pixel sensitivity as I wasn't sure what it was I was looking at as I have seen hot pixels like that before. I will also try dithering as well if required.
Thanks.