I started using Live Stack a few weeks ago and am very happy with everything overall. But I need help on one area. Except for one or two captures, nearly every time I used Live Stack, the displayed image would be blown out or too dark. I tried using the auto stretch on the display histogram and I tried using the auto color balance on the Live Stack histogram. I was able to drag the manual histogram dashed controls, but the response on the display was always delayed and sometimes, just a tiny move left or right would simply go to blown out or dark. It all seems sloppy and not nearly as consistently high quality as the rest of Sharp Cap. So I feel like I must be missing something because I was expecting a quick auto-stretch would keep the display exactly where it needs to be.
Can you please go over your suggestions to maintain a enjoyable view of the Live Stack targets as they are coming in? Am I missing a control or misunderstanding how Live Stack display works?
Use of Live Stack and Histogram
Forum rules
If you have a problem or question, please check the FAQ to see if it already has an answer : https://www.sharpcap.co.uk/sharpcap-faqs
If you have a problem or question, please check the FAQ to see if it already has an answer : https://www.sharpcap.co.uk/sharpcap-faqs
-
admin
- Site Admin
- Posts: 17468
- Joined: Sat Feb 11, 2017 3:52 pm
- Location: Vale of the White Horse, UK
- Contact:
Re: Use of Live Stack and Histogram
Hi,
the display histogram stretch on the right is a very blunt tool for this sort of thing, so it is best to turn that off (or reset it to default no stretch) while live stacking. You should make your adjustments in the live stacking histogram, colour balance and background subtraction areas.
The easy way to do all of this with one button press (if you have a fully up-to-date version of SharpCap) is to use the 'Colour Calibration' tab and press the 'Calculate' button - this detects stars in the image, measures their colours and matches the stars up with known stars in the plate solving database to see how the image colours differ from the known catalog colours of the stars. This allows the colour balance adjustments needed to balance the image to be calculated 'scientifically' as well as the background sky glow that needs to be subtracted away. With one button press the three colour balance sliders are set, the three background subtraction sliders are adjusted and a reasonable stretch is set up to show most deep sky objects. It's not 100% fool proof, and works better after a few frames have reduced the noise level, but in most situations it works really well.
For manual adjustments, there are a lot of things that help you make the fine adjustments to the settings that are needed - setting the live stack histogram into 'logarithmic horizontal axis mode' or using the zoom function to see the area of interest in more detail helps, but there are also techniques to help make finer adjustments - see https://docs.sharpcap.co.uk/4.1/#Making ... 0Histogram for more info.
cheers,
Robin
the display histogram stretch on the right is a very blunt tool for this sort of thing, so it is best to turn that off (or reset it to default no stretch) while live stacking. You should make your adjustments in the live stacking histogram, colour balance and background subtraction areas.
The easy way to do all of this with one button press (if you have a fully up-to-date version of SharpCap) is to use the 'Colour Calibration' tab and press the 'Calculate' button - this detects stars in the image, measures their colours and matches the stars up with known stars in the plate solving database to see how the image colours differ from the known catalog colours of the stars. This allows the colour balance adjustments needed to balance the image to be calculated 'scientifically' as well as the background sky glow that needs to be subtracted away. With one button press the three colour balance sliders are set, the three background subtraction sliders are adjusted and a reasonable stretch is set up to show most deep sky objects. It's not 100% fool proof, and works better after a few frames have reduced the noise level, but in most situations it works really well.
For manual adjustments, there are a lot of things that help you make the fine adjustments to the settings that are needed - setting the live stack histogram into 'logarithmic horizontal axis mode' or using the zoom function to see the area of interest in more detail helps, but there are also techniques to help make finer adjustments - see https://docs.sharpcap.co.uk/4.1/#Making ... 0Histogram for more info.
cheers,
Robin