I have looked into this several times in my 6 years of Astro imaging but always given up hopelessly lost.
I have never used the sequence planner - am I going to have to use that?
Information on setting up dithering I have found refers to livestacking. I have never livestacked.
I set up capturing and go to bed.
How do I add in this mystical dithering?
How do I set up dithering?
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Re: How do I set up dithering?
Hi,
the key with dithering is that you are asking the guiding application (PHD2 probably) to move the mount deliberately. This has to happen between frames otherwise you will get ruined frames. In SharpCap you have three options for this
1) (Relatively Easy) - Use Live Stacking. You do this instead of capturing, but you set the 'Raw Frames' option to 'Save Except when Paused/Dithering', which makes SharpCap save all the individual camera frames for you as well as stacking them, which gives you the images you want (although they may get saved in a slightly differently named folder to normal). See https://docs.sharpcap.co.uk/4.1/#Left%20Panel for the 'Raw Frames' option.
You also go to the 'Guiding' tab in live stacking (https://docs.sharpcap.co.uk/4.1/#Guiding%20Tab), tick the box to ask SharpCap to monitor PHD2 and then tick the 'Automatically Dither' and 'Reduce Exposure while Dithering' boxes. Set the interval between dithering (maybe every 5 or 10 frames).
When set up like this, SharpCap will make a live stacked image on screen (which you can ignore), but will also be saving the raw images from the camera (which you want). SharpCap will ask PHD2 to perform a dither at the specified intervals, and will temporarily drop the exposure to 2s during the dither, then put the normal exposure back when it is over. Due to the 'Save Except when Paused/Dithering' choice, you won't get the 2s exposured saved among the other ones.
2) (Intermediate) - Use the Deep Sky Sequence Planner. This is more like the sort of capturing you are used to, but you leave some or all of the setup to SharpCap's sequencing tools. Mainly, checking boxes in the 'Guiding' tab to set up dithering in a similar way to the Live Stacking option above. If you are going to set up all your gear manually as you currently do (targeting, focus, camera settings, etc), then untick everything in all the other tabs so that SharpCap won't do anything unexpected like try to change camera setting for you. Then you just need to tell it how many light frames to capture and press the 'Run' button. Well worth doing some tests first with you watching to make sure it is doing the right things before you trust this to work unattended. See https://docs.sharpcap.co.uk/4.1/#!2!Dee ... %20Planner for more info.
3) (Advanced) - Use the full Sequence Editor - this is like a mini programming language for making SharpCap do things - only really for advanced users, so I will not cover it in more detail here except to note that the 'Deep Sky Sequence Planner' takes all the things you have ticked or not ticked and other choices you have made and automatically turns it into a program for the sequence editor for you. So, this option is mainly for people who try using the Deep Sky Sequence Planner and then find they want more flexibility.
One more thing to note is that for any of these to work, PHD2 needs to be running an set up to guide correctly. You also need to make sure the 'Enable Server' item in the PHD2 Tools menu is ticked, otherwise SharpCap cannot communicate with PHD2 to check status and request dithering movements.
A final point to note is that dithering is usually used to help deal with trails of hot pixels or 'walking'/'raining' noise in the final image. By introducing random movements it makes these things less noticeable to the human eye (it doesn't really reduce them, just breaks up the patterns that otherwise show). If you are not encountering these sorts of isues then dithering may not be necessary.
cheers,
Robin
the key with dithering is that you are asking the guiding application (PHD2 probably) to move the mount deliberately. This has to happen between frames otherwise you will get ruined frames. In SharpCap you have three options for this
1) (Relatively Easy) - Use Live Stacking. You do this instead of capturing, but you set the 'Raw Frames' option to 'Save Except when Paused/Dithering', which makes SharpCap save all the individual camera frames for you as well as stacking them, which gives you the images you want (although they may get saved in a slightly differently named folder to normal). See https://docs.sharpcap.co.uk/4.1/#Left%20Panel for the 'Raw Frames' option.
You also go to the 'Guiding' tab in live stacking (https://docs.sharpcap.co.uk/4.1/#Guiding%20Tab), tick the box to ask SharpCap to monitor PHD2 and then tick the 'Automatically Dither' and 'Reduce Exposure while Dithering' boxes. Set the interval between dithering (maybe every 5 or 10 frames).
When set up like this, SharpCap will make a live stacked image on screen (which you can ignore), but will also be saving the raw images from the camera (which you want). SharpCap will ask PHD2 to perform a dither at the specified intervals, and will temporarily drop the exposure to 2s during the dither, then put the normal exposure back when it is over. Due to the 'Save Except when Paused/Dithering' choice, you won't get the 2s exposured saved among the other ones.
2) (Intermediate) - Use the Deep Sky Sequence Planner. This is more like the sort of capturing you are used to, but you leave some or all of the setup to SharpCap's sequencing tools. Mainly, checking boxes in the 'Guiding' tab to set up dithering in a similar way to the Live Stacking option above. If you are going to set up all your gear manually as you currently do (targeting, focus, camera settings, etc), then untick everything in all the other tabs so that SharpCap won't do anything unexpected like try to change camera setting for you. Then you just need to tell it how many light frames to capture and press the 'Run' button. Well worth doing some tests first with you watching to make sure it is doing the right things before you trust this to work unattended. See https://docs.sharpcap.co.uk/4.1/#!2!Dee ... %20Planner for more info.
3) (Advanced) - Use the full Sequence Editor - this is like a mini programming language for making SharpCap do things - only really for advanced users, so I will not cover it in more detail here except to note that the 'Deep Sky Sequence Planner' takes all the things you have ticked or not ticked and other choices you have made and automatically turns it into a program for the sequence editor for you. So, this option is mainly for people who try using the Deep Sky Sequence Planner and then find they want more flexibility.
One more thing to note is that for any of these to work, PHD2 needs to be running an set up to guide correctly. You also need to make sure the 'Enable Server' item in the PHD2 Tools menu is ticked, otherwise SharpCap cannot communicate with PHD2 to check status and request dithering movements.
A final point to note is that dithering is usually used to help deal with trails of hot pixels or 'walking'/'raining' noise in the final image. By introducing random movements it makes these things less noticeable to the human eye (it doesn't really reduce them, just breaks up the patterns that otherwise show). If you are not encountering these sorts of isues then dithering may not be necessary.
cheers,
Robin