Dithering with NINA and Mach2 #Mach2GTO


midmoastro
 

I have never dithered before, but it appears NINA supports it when connected to PHD2.
Has anyone ever done this with the Mach2 and NINA? Is it really needed, or does it help?

Todd


midmoastro
 

I think I figured out the issue, thanks to Linwood and Iseborn in the NINA Discord chat.
That said, I assume this is a good practice to get in to? I should have clear skies tonight and will give it a try.
Todd


Richard Hennig
 

Dear Todd,

I always dither to reduce the noise in the stacked images that come from the slightly different responses of each pixel in the imaging sensor (CCD or CMOS). Also, it helps minimize the effect of dead or hot pixels, which are removed as outliers during stacking dithered images.

All you need to do in NINA is to tell it in the guiding tab how many pixels you like to dither and how often. With the Mach2, I dither every images for longer sub exposures (3 - 10 min) and less frequent for shorter ones. I usually dither by something like 5 pixels.

Clear skies,
Richard

— 
Richard G. Hennig
Professor and Alumni Professor of Materials Science and Engineering
Associate Director, Quantum Theory Project
Department of Materials Science and Engineering, University of Florida
Email: rhennig@...
Web: http://hennig.mse.ufl.edu

On Jun 28, 2022, at 9:15 AM, midmoastro <teche70@...> wrote:

I have never dithered before, but it appears NINA supports it when connected to PHD2.
Has anyone ever done this with the Mach2 and NINA? Is it really needed, or does it help?

Todd


Dean Jacobsen
 

On Tue, Jun 28, 2022 at 06:22 AM, midmoastro wrote:
That said, I assume this is a good practice to get in to? I should have clear skies tonight and will give it a try.
Absolutely give it a try.  In addition to the noise benefit, if you use PixInsight you can use your dithered images to leverage Drizzleintegration for your mono images or CFA drizzle with color camera images.
 
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/


midmoastro
 

Richard and Dean,

Thank you for the input. I will give it a try tonight as it appears I'll have some nice weather.
I just started using PI so I will give that a try using CFA, thanks Dean.
I usually end up around five minutes exposures for most things but tonight its comet time so I suspect 90 seconds will be my max.
I'll see what the default is in NINA and maybe try 5 pixels.

Todd


Dean Jacobsen
 

Excellent, here is a post from Juan Conjero - the author of PixInsight - regarding using CFA drizzle for color cameras:

https://pixinsight.com/forum/index.php?threads/bayer-drizzle-instead-of-de-bayering-with-osc.12996/

You can set the scale at 2 if your camera is undersampling, otherwise he recommends setting the scale to 1.

You have to set the CFA Drizzle option in the StarAlignment tool and then add the drizzle data to the stack during ImageIntegration.  The "Generate Drizzle Data" box is also selected during ImageIntegration.  Then, lastly, you can run the DrizzleIntegration.

If you are interested in drizzle integration, there are more posts on the PI forum regarding usage.  Here is the too announcement back in 2014 to get you started:

https://pixinsight.com/forum/index.php?threads/new-drizzleintegration-tool-released.6911/

The CFA drizzle is something that I use every time with my color cameras.
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/


midmoastro
 

Again, thanks everyone. I've been experimenting with this, as well as PixInsight.
Still much to learn but here is the latest attempt using both.
While I took dark flats and flats, I have not yet taken darks.
Thanks for the tips,
https://astrob.in/gw0xv4/0/

Todd


Dean Jacobsen
 

Great result for for just over an hour.  Keep us posted.
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/