Please Help with Dithering

Discussion of using SharpCap for Deep Sky Imaging
Post Reply
ScottD
Posts: 43
Joined: Mon May 04, 2020 2:45 pm

Please Help with Dithering

#1

Post by ScottD »

Hello,

I'm pretty new to imaging. I've been using Sharpcap and PHD2 but was recently told that I need to start dithering to eliminate some of the noise. I've been reading and trying to figure out how to set this up, but it seems everyone is already well underway and their discussions are way over my head. Can anyone help with settings if I give you my setup?

I am using a CGX mount with an 8" f3.9 Newtonian with a QHY294C imaging camera and a ZWO120mini as a guide camera on a 60mm x 240mm guide scope. I use a light pollution filter and a coma corrector. My images have been pretty good, but I'd like to get them much smoother.

I'm planning on going out in the next few nights. I'll be taking 2 minute light exposures. From what I've gathered so far, I should be dithering around every third frame, so my interval should be 360 seconds, correct? As for the other settings, I'm not at all sure what to set those at. Any advice would be greatly appreciated.

Thank you,

Scott
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Please Help with Dithering

#2

Post by admin »

Hi Scott,

in the current version of SharpCap, dithering support is only available while you are running the live stacking functionality. Once you have activated live stacking, you will see that there is a 'Guiding' tab which has all the appropriate settings on it. You can find more documentation about how to set things up here:

https://docs.sharpcap.co.uk/3.2/#Guiding%20Tab

One thing that several members of the forum have taken advantage of is that you can use live stacking and also save the unprocessed frames for later reprocessing. This allows you to take advantage of the dithering functionality in live stacking even if you want to use another stacking application for your final image.

Hope this helps, Robin
ScottD
Posts: 43
Joined: Mon May 04, 2020 2:45 pm

Re: Please Help with Dithering

#3

Post by ScottD »

Thank you Robin. I appreciate the follow up. I guess my question was more about how long the minimum and maximum settle times should be, as well as the maximum dither step. I will experiment and see what works best. Again, your follow up is much appreciated!

Regards,

Scott
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Please Help with Dithering

#4

Post by admin »

Hi Scott,

I'd leave the defaults alone unless/until you run into problems with them :)

cheers,

Robin
ScottD
Posts: 43
Joined: Mon May 04, 2020 2:45 pm

Re: Please Help with Dithering

#5

Post by ScottD »

Robin,

Now you're really going to get tired of me. I already messed with them. Can you kindly tell me what the default settings are? I'm so sorry for this bother.

Cheers,

Scott
User avatar
turfpit
Posts: 1779
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
Contact:

Re: Please Help with Dithering

#6

Post by turfpit »

Scott

I have never used dithering which means these will be default values in SC 3.2.

dithering-defaults.JPG
dithering-defaults.JPG (44.19 KiB) Viewed 1175 times


Hint: in any technical environment, before making changes, record values so that regression is possible.

Dave
ScottD
Posts: 43
Joined: Mon May 04, 2020 2:45 pm

Re: Please Help with Dithering

#7

Post by ScottD »

Thank you Dave! You are very kind to take the time to post this. And you're right, I should always record original settings. Again, much appreciated!

Scott
User avatar
admin
Site Admin
Posts: 13177
Joined: Sat Feb 11, 2017 3:52 pm
Location: Vale of the White Horse, UK
Contact:

Re: Please Help with Dithering

#8

Post by admin »

Hi Scott,

I was going to suggest using the reset button which is on the log tab in the live stacking area – that's supposed to reset all the live stacking settings to their defaults. Then I noticed that it doesn't reset the guiding settings properly... (he scurries off to fix the code)...

Cheers, Robin
Post Reply