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Nikon D700 - Red Banding on Bright Object - Stacking ?

Nikon D700 M42 Banding Messier Objects Deep Sky
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Ian Coopland avatar
Ian Coopland avatar
Good Morning All,

I have my first scope and at the minute using A full Frame Nikon D700 until I purchase more equipment over the next few months.

I capture M42 using 250 x 30 Second exposures at Iso 800 and when stack any bright object star , core etc has really bright red banding ! I have over stretched the image below to to highlight the banding. 

Banding.jpg

I have seen some stunning images taken with the Nikon D700 with some guided exposures of 300 Seconds that are very clean ? 

IS stacking a large amount of images making the banding worse for me and is there a suggested stacking method to remove ?

Here is an example of same camera with less longer subs.

https://www.astrobin.com/h37izk/

Stacking ASTAP
Process Siril
OTA Explore Scientific 127mm Triplet CF
Field Flattner 

Thank you everyone !
andrea tasselli avatar
andrea tasselli avatar
What is your calibration procedure? Because it is all in there…
Ian Coopland avatar
Ian Coopland avatar
Thank you for your reply. 

I captured around 30 Darks with 3d printed cover on scope, 30 or so flats using a usb light panel .. I did this using a exposure time so histogramm was around 50% ( hope this is ookay as seen a few variations ) and then 30 bias at fastest shutter speed again with scope cap on. 

ASTAP would not use the bias frames so hope all the above is the correct procedure.

Regards
andrea tasselli avatar
andrea tasselli avatar
1. Do not use ASTAP, use Siril for calibration and everything else
2. The issue with those old models is most likely with the bias, specifically with bias signal removal from both flats and darks, flats being signally the more troublesome.

Procedure (which should be easily handled within Siril) is:

Creation of master bias
Creation of master dark (with or without bias subtraction). My choice would be NOT to remove the bias signal from the darks to reduce numerical errors.
Creation of master flat WITH bias subtraction
Calibration of the light frames >> (L- Bias - (Dark - Bias))/(Flat - Bias) or (L - DarkwithBias)/(Flat - Bias) [note: this is handled by Siril in streamlined fashion]

ALL of the above MUST be carried out with ALL the calibration frames having the same ISO speed of the light frames you are calibrating.

After all have been said and done old CMOS sensors do not do great so to mitigate those banding issues significant dithering during acquisition is a very much recommended practice.
Helpful
Ian Coopland avatar
Ian Coopland avatar
I really appreciate your advice and will give that a go very soon.

Thank you.
Well Written Respectful