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Rings in image?

Askar 103APO Dew Heater Acquisition Solar System Artifacts
Konstantinandrea tasselli
•30 replies•791 views
Konstantin avatar
Konstantin avatar
Refractor: 103APO, Camera: Canon EOS R6

I highly doubt its reflection rings because i have the dew shield extended, the camera doesnt emit light when shooting either. Been having this issue for a year, not sure if it could be the reducer or the telescope or possibly humidity and dew.


Below one i took tonight, full moon was out and cloudy, only meant as an update.

This February


Around last summer
All of the above where without flats.
This one below is with flats and as you can see still doesnt dissappear. Using Siril for all of these.
Now i theorise that it could be dew, as it seems much less pronounced now and more pronounced in the winter. I am also getting similar patterns with my camera lense. Using the same camera. Noting that feburary looks strainge to me as it distributed as a ring that the if it were water, it would accumulate at the top end, imagining the glass lense as convex upwards


So the point being.
Should i invest in a better dew heater or could this be another issue?
Konrad Krebs avatar
Konrad Krebs avatar
I don't know if this is helpful, but I have a somehow similar problem with one of my cameras in combination with two of my telescopes. Maybe it is pupil ghost artifact?
Zeb Németh avatar
Zeb Németh avatar
With just the information you gave to gon on, this came to mind;
Nikon infamously has this problem, haven't seen any definite solutions. 

For instance, see https://www.dpreview.com/forums/thread/1941842

If you give more specifics on your gear and history of results (were there no rings before?), I hope you might get more concise answers.
Konstantin avatar
Konstantin avatar
Konrad Krebs:
I don't know if this is helpful, but I have a somehow similar problem with one of my cameras in combination with two of my telescopes. Maybe it is pupil ghost artifact?

This is extremely interesting!!! Will look into it!
Konstantin avatar
Konstantin avatar
Using and Askar 103APO with a 0.6x reducer. Canon R6.
Konstantin avatar
Konstantin avatar
Using and Askar 103APO with a 0.6x reducer. Canon R6.
andrea tasselli avatar
andrea tasselli avatar
It's a light leak, see my message on the issue: Light Leaks - AstroBin
Michele Rainville avatar
Michele Rainville avatar
Looks like condensation on the sensor. Had it same once dew/frost. Cool your camera slower for a try.
Konstantin avatar
Konstantin avatar

andrea tasselli:
It's a light leak, see my message on the issue: Light Leaks - AstroBin

5 min dark exposure in bright direct sunlight from above. It doesnt seem to be a light leak, granted there is a leak in the top right, but it doesnt seem to be causing any rings. I will make sure to covering the top right one anyway, but i dont think this is the cause of the issue.
Christian Bennich avatar
Christian Bennich avatar
I would also argue that this is a light leak. I have just gone through a similar experience. 

https://www.astrobin.com/forum/c/astrophotography/deep-sky-processing-techniques/problem-identifying-what-my-artefact-problem-is

As your setup is very different from mine, it could naturally be different in your case.
andrea tasselli avatar
andrea tasselli avatar
5 min dark exposure in bright direct sunlight from above. It doesnt seem to be a light leak, granted there is a leak in the top right, but it doesnt seem to be causing any rings. I will make sure to covering the top right one anyway, but i dont think this is the cause of the issue.


*It's a light leak all-right. Light leaks are additive in nature so even a reflection is in fact a "light leak". Yours might be due to the camera adaptor (on top of the side leak) and won't be revealed with the dark. If I had a penny-worth for each time I have seen this I'll be retired by now...
Konstantin avatar
Konstantin avatar
I hope you guys are right, my next clear night im going to literally cover the whole focuser and adapter/camera.
Andrew avatar
Andrew avatar
Konstantin:

andrea tasselli:
It's a light leak, see my message on the issue: Light Leaks - AstroBin

5 min dark exposure in bright direct sunlight from above. It doesnt seem to be a light leak, granted there is a leak in the top right, but it doesnt seem to be causing any rings. I will make sure to covering the top right one anyway, but i dont think this is the cause of the issue.

Whether it’s in direct sunlight or not you should be able to take a dark frame and have 0 leaks.

your dark frame should be completely black when unstretched and when stretched you should only see a noise floor there should be no colors besides what appears to be hot pixels on the pixel level. 

regardless if this is the solves the ring issue this is destroying your data because your calibration frames are messed up. 

you should also solve the leak at its source because depending on the severity of the leak it could be causing issues to your lights as well. 

Shinning a flashlight at various areas of the entire imaging train+telescope while taking a dark frame can help narrow it down.

common spots for leaks:
threads
focuser
Loose screw
filter wheel/drawer
OAG
Konstantin avatar
Konstantin avatar

Last night, I had the entire adapter covered, with a pair of socks, leather gloves, a neck warmer over it and a couple pieces of paper for good measure. You can argue it is not perfect, but i think if it light leaks were the problem it would have at the very least reduced it. Used 35 second subs
CaptnCook avatar
CaptnCook avatar
Are you using a flattener? Try without then as last resort try with a different camera.
Its not dew or light leak.
Konstantin avatar
Konstantin avatar
Are you using a flattener? Try without then as last resort try with a different camera.
Its not dew or light leak.

Using a reducer 0.6x
Konstantin avatar
Konstantin avatar
Are you using a flattener? Try without then as last resort try with a different camera.
Its not dew or light leak.

I can try using a flattener in a few weeks, in efforts to NOT replace my only camera i have, any theories as to how it could be my sensor? Is it frost?
Christian Bennich avatar
Christian Bennich avatar
I stripped down my image train to just the camera and nothing else. 
Did as you did - covered up everything and believed that all was good. 

When I took out the scope in broad daylight and still saw even the tiniest of reflections I could see that my OTA was not light proof. 

I reflocked part of my OTA, painted parts of my focuser with black musou paint. 
I kept seeing the same artefacts. 

Continued until I could do 5 minute Light exposures in daylight without any hint of reflections at all. 

Then I tried at night again, and at least in my scenario, the artefact was now effectively gone. 

If you only have the camera in your train, at least you rule out whatever is connected to the camera. 
Whether you have other internal reflections in your scope, is beyond my knowledge. 

I hope you figure it out soon.
Helpful Insightful
CaptnCook avatar
CaptnCook avatar
Konstantin:
Are you using a flattener? Try without then as last resort try with a different camera.
Its not dew or light leak.

I can try using a flattener in a few weeks, in efforts to NOT replace my only camera i have, any theories as to how it could be my sensor? Is it frost?

I meant remove any element inbetween your OTA and sensor (so flattener OR reducer)- take that out and see if theres any change. Next culprit might be your camera itself although anything on the sensor would be very dark.
Konstantin avatar
Konstantin avatar
What i should mention is that, right when i bought this telescope, the noob i am, i tried taking photos with it, with no backspacing from the reducer to the camera. Thus my images has stars stretched at the edges. I adjusted the draw tube so that the focus in the center of the frame was correct. So for every image i had to crop it significantly to the centre of the image to get a good image, back then i did not have rings. I will try next time to take photos without the spacers to see if the rings disappear again.



However i do not know specifically what this would imply.
Konstantin avatar
Konstantin avatar
Not on this one either, around the same time, before i got the spacers


andrea tasselli avatar
andrea tasselli avatar
As I mentioned before, internal reflections, such as those caused by reflective surfaces in adapters/rings/spacers/etc, act as virtual "light leaks" thus affecting calibration. By the look of things your case could  be most likely due to such an occurance thus removing the spacers (or not having them in the first place) removes the cause of the additive light and hence "the ring".
Concise
Konstantin avatar
Konstantin avatar


Maybe I am winding myself up. But in another image with no back spacing i notice the ring again, except it is much wider and far out of the circle. Which intuitively makes sense, as the further out i pull the camera, the smaller the ring gets. To test my hypothesis, on my next night, i am going to purposefully increase the backspacing of the camera and reducer past 55mm. I believe the ring will get smaller and more intense. If that happens, then its an issue with the reducer and camera combination so i do not know how i could fix it anyway.
John Hayes avatar
John Hayes avatar
That’s a calibration issue caused by stray light—either from stray reflections or a light leak.

John
Well Written Concise
Ed Astle avatar
Ed Astle avatar
You do have the reducer around the right way?
A reducer around the wrong way "seems to work" but gives a bright outer ring, the antithesis of vignetting.

I know this because I recently got my Daystar 0.5x around the wrong way for solar work.
I looked at every conceivable point of failure before there was only one left - me!

I had T2 both sides and I wasn't paying attention…
Helpful Concise Supportive