Rising Cam IMX 571 gradient issues

[Clarkey]

Thanks again @ONIKKINENand @tomato, I really appreciate the help.

I think I will go through all the settings again to make sure everything is as it should be - including the dark frames. I might just have to persevere a bit more. I only got an OSC as I thought it might be a bit easier.🤣 Should have stuck with mono.

9 hours ago, tomato said:

the dust motes look strange on your flat, they are rings rather than filled circles

This seems quite normal for the RC8. I'm guessing it something to do with the secondary obstruction.

FLAT_Lum_2021-02-12_08-01-47_-20.00_0.44s_2x2_139(1).fits

[tomato]

48 minutes ago, Clarkey said:

Thanks again @ONIKKINENand @tomato, I really appreciate the help.

I think I will go through all the settings again to make sure everything is as it should be - including the dark frames. I might just have to persevere a bit more. I only got an OSC as I thought it might be a bit easier.🤣 Should have stuck with mono.

This seems quite normal for the RC8. I'm guessing it something to do with the secondary obstruction.

FLAT_Lum_2021-02-12_08-01-47_-20.00_0.44s_2x2_139(1).fits 7.82 MB · 0 downloads

Ok apologies, that does make sense on the dust mote shapes. I have only ever seen ones from refractors and a RASA, I forgot what kind of scope you were using.

[Oddsocks]

I meant to post a comment last week but got caught up with other things and could not get back here until today.

When I looked at your opening posts and screen grabs they reminded me of images taken through a RC OTA with a mono cam that had no IR blocking filter.

The "donut" overcorrected image after flats were applied were typical of that system as off-axis IR found its way to the sensor by glinting off the RC focus extension tubes, which were only anodised black and therefore highly reflective in the IR band.

Unless the IR content of the flats source matches the night sky then calibration with the flat will over or under correct when a IR blocking filter is missing.

I had a look at what I could find regarding the Risingcam IMX571 camera window specification and could find nothing about whether it was IR blocking in the colour version or not.

If the camera is not natively IR blocking and you don't have a IR blocking filter added as a supplementary filter then it might be worth trying a cheap IR/UV blocking filter in front of the camera window, if nothing else just to dismiss that as a possible cause?

Edited December 14, 2022 by Oddsocks

[ONIKKINEN]

2 hours ago, Oddsocks said:

I had a look at what I could find regarding the Risingcam IMX571 camera window specification and could find nothing about whether it was IR blocking in the colour version or not.

Its not very clear even if one knew where to look, but earlier than last july models of the camera had either an AR coated window at around 300-1000nm or a UV/IR window that cuts off at 650nm (before Ha! Which is why most people have the AR coated version). New options are an AR or a proper UV/IR window that passes Ha and sulfur and ends somewhere around 700nm i believe.

[tomato]

Yes, when I purchased the OSC  version a year ago, I had to specify if I wanted the AR or UV/IR window on the order. I specified the AR window and use a separate UV/IR cut filter with it.

[Clarkey]

Mine is the AR window - but all imaging is done using either an IR filter or NB filters - so IR can be ruled out.

I have gone back over my darks and the offset is definitely wrong - so this could well be having a factor. I am in the process of re-creating all of the darks to see if this gives an improvement.

Unfortunately, due to unforeseen circumstances my AP hobby is going to be put on hold for a while - so I am going to have to wait a while to see if I can sort this problem out.