Help With Walking Noise?

[BlakPhoenix]

Hi all,


I have been shooting on my RedCat51 and ASI294MC Pro the last few nights and when I went to stack them today I ended up with a HUGE amount of noise in the images. I've attached a scaled full image as well as a 100% crop so you can see the details of it. The full set up is a EQ6-R Pro mount and I was using the IDAS LPS D2 light pollution filter + ZWO 60mm guide scope & ASI290mm Mini.



The total stack is about 4 hours of integration time. 45 second exposures at 120 gain & -10C, with full dark library, 20 flats, and 20 flat darks.


I was dithering every 2nd image, with PHD set to dither in a random way, up to 5 pixels with a guide to main camera scale of 2:1.


I'm scratching my head as to why I have so much noise even while dithering. What am I doing wrong??

[glend]

I would suggest you run those subs through an image grader and find out just what sort of data your dealing with.

https://www.sequencegeneratorpro.com/download/fits-image-grader/

Have a close look at the good ones and the bad ones. Post up example subs here.

And what are you stacking with? DSS? Something else?

[BlakPhoenix]

Thanks Glen, I did a grade of the FITS and most images came out at about a 70 score. Here's two links two files, one of the best and one of the worst:


www.astrowithroro.com/img/0003_45.00S_120G_-11.10C.fits
www.astrowithroro.com/img/0198_45.00S_120G_-10.00C.fits


The worst files are early in the night as the target was lower on the horizon.


I am stacking using the WBPP in Pixinsight.

[BlakPhoenix]

Just an update on this. I have discovered that dew is forming on the sensor when it is cooled which could be causing fogging all over the sensor. I have contacted Bintel to see if this is under warranty or if I need to open the camera and fix it myself. A bit dissapointing given the camera has always been well looked after and is only just a year old.

[Dennis]

It does look like the frosting that I used to get with my SBIG ST2000XM camera at -10 deg C and lower, which I "fixed" by baking the removable dessicant plug.

If the camera is a low noise camera, maybe set the cooling to say +5 deg C so the moisture doesn't get the chance to turn to fingers of frost?

Cheers

Dennis

[BlakPhoenix]

Thanks for this info Dennis. I have talked with Bintel about this issue and they are going to send it back to ZWO for repairs under warranty. I will keep this thread updated as the process continues.

[Nikolas]

it's an easy fix, you open the camera, remove the dessicant tablets stick em in the microwave and poof you are done, put them back in and you are ready to go. ZWO even have instructions on how to do this. Sending it back to bintel who will send it back to zwo will take you months of wasted time for a simple fix.

[BlakPhoenix]

I agree that I probably could have done it all myself, however I just received the 294MM so I still have toys to play with and would rather it go off and be fixed under warranty as if I decide to sell the 294MC now that I have a mono cam, I'd feel better that it were "factory fixed/new" than recently opened and meddled with by me.

[The_bluester]

When I had frosting on my 294 it showed up much more strongly in the middle of the FOV. It was most obvious on flats and showed up as a weird sort of tetris like crystalline pattern.

I baked the dessicant, but be aware that if you open it up and bake the tablets you would likely end up with dust bunnies, and you may also still see moisture effects for a while. It took a week or so after I backed the tablets for them to suck up the moisture in the chamber and stop it frosting.