Weird spot in Rasa 8 images all the sudden

Hey all! I have an odd spot showing up in my rasa images that seems to only be in the light frames. If i rotate the camera 180⁰, the spot is then on the opposite corner so I don't believe it to be the camera sensor. It's there with or without a filter, and with or without moonlight from any direction. Underneath should be a ridiculously stret hed image to help see the spot im talking about. Upper left center area...almost looks like a yinyang.Thank you for any advice!

I am not sure for certain about this, but when you say spot I assume you mean that large circularity, that you say looks like a yin and yang. All I can tell you is that with bright stars, and certainly with brighter stars, I get some odd internal refractions and reflections through the optics and if they are significant enough I simply have to clone them out. At least that is what I think is causing these issues. I have not had anything as bad as this but then you are imaging an extremely bright star in that region. It might be worth imaging elsewhere with a less bright star or with just a regular star field, to see if the same problem occurs. My gut feeling is that it is probably something to do with Alnitak. Hoping you get this sorted!!

Normally I would agree, but it shows up no matter what I try to image now. I've actually got an image of the horsehead region on here that has nothing like that. I did an experiment and pointed the scope at my house and it still showed up….so I'm kinda lost at the moment.

It seems you have unwanted reflections in your optical train.

andrea tasselli:
It seems you have unwanted reflections in your optical train.

*** Do you know if anything in that 4 piece lens group can shift at all? I ask that because I really don't believe this particular issue is coming from the tube itself, but rather the light cone is being shifted somehow in that lens section?

It is indeed possible that the corrector group is responsible for this issue. Hard to figure out how this happened though. Best bet is remove and re-insert and see what happens.

andrea tasselli:
It is indeed possible that the corrector group is responsible for this issue. Hard to figure out how this happened though. Best bet is remove and re-insert and see what happens.

*** I was worried you were gonna say that 🤣

What filter are you using? I had similar issue in the past and it was the filter was tilted since I was using a 36mm filter attached to an adapter 36-2”.

Rodrigo Roesch:
What filter are you using? I had similar issue in the past and it was the filter was tilted since I was using a 36mm filter attached to an adapter 36-2”.

*** That was just the clear glass that comes stock in the Rasa in that image, but I did try the rasa light pollution filter too and got the exact same result.

Did you try it with different camera? If you don’t have another camera, just rotate it and see if the position of the artifact changes. Do you see that on the raw pictures?

Rodrigo Roesch:
Did you try it with different camera? If you don’t have another camera, just rotate it and see if the position of the artifact changes. Do you see that on the raw pictures?

*** I only have 1 camera that can work on the rasa, but I did rotate it 90⁰ and 180⁰ and the spot is in a different position that corresponds to the rotation. I also installed the camera on another scope just to make sure it's not the camera itself.

If the artifact moved, the it is the camera. Check the cameras window and the sensor under a bright light

Rodrigo Roesch:
If the artifact moved, the it is the camera. Check the cameras window and the sensor under a bright light

*** If it's the camera, it should show up no matter what scope it's on though I thought. And if it was the cam or something on the sensor then the spot should stay in the same spot of the field...as in if I move the camera, the spot should move with it, which it doesn't. The camera looks extremely clean.

If you move the camera and the camera has the spot, you will be moving the spot with the field, the the position will change in reference to the scope The field is always the same because the spot it is fixed there, but the field will rotate with the spot. So in other words if you measure the distance from the center of the field to the spot, it will be always the same and if you rotate the camera, it will appear on the other side but the distance from the center of the field to the spot will be still the same. That will show the camera is the problem. Also look at your raw frames to make sure the artifact was not introduced with the flats

Rodrigo Roesch:
If you move the camera and the camera has the spot, you will be moving the spot with the field, the the position will change in reference to the scope The field is always the same because the spot it is fixed there, but the field will rotate with the spot. So in other words if you measure the distance from the center of the field to the spot, it will be always the same and if you rotate the camera, it will appear on the other side but the distance from the center of the field to the spot will be still the same. That will show the camera is the problem. Also look at your raw frames to make sure the artifact was not introduced with the flats

*** I did check the flats and didn't see anything in there. The distance and position from the spot definitely changes. Kinda like if you take a piece of paper and take a pencil and poke a hole in it away from the center...stay in that position and keep poking holes as you rotate the paper...that's how the spot is moving in relation to the sensor.

Ok, then it is in the scope, check if you corrector plate as well as the clear glass filter are clean. It will be hard to believe there is something inside, but not impossible

Rodrigo Roesch:
Ok, then it is in the scope, check if you corrector plate as well as the clear glass filter are clean. It will be hard to believe there is something inside, but not impossible

*** Unfortunately, I didn't see anything in there. The scope is still pretty new (from November) and I baby it. The image really almost seems like if the light cone is being shifted by one of the glass elements in that 4 lens assembly, but Celestron specifically says not tp touch that stuff.

At this point, take another set of pictures, just maybe flats to confirm the problem is still there, then create a ticket with Celestron. They should cover everything for the repair. Don’t open it or it will void the warranty

Rodrigo Roesch:
At this point, take another set of pictures, just maybe flats to confirm the problem is still there, then create a ticket with Celestron. They should cover everything for the repair. Don’t open it or it will void the warranty

*** Alrighty, I'll definitely create a ticket with their support and see what they say.Don't worry...I'm not opening that thing up 🤣 I don't trust myself that much.

From the size of it i guess it is a defocued speck of dust on the flattener lens. (The one you see when the camera is removed). Looks odd though, but that could be because it is not quite succesfully removed by the flatframe.

Hi, your problem is the camera and backfocus.
Tell all about your setup, how your cmos is attached to the Rasa.
or provide your backfocus calculation for your equipment and setup.
The circle is created by light beyond focus. The spot is an image of your clear glass located in the optical train, normal if the cmos is not exactly at the required backfocus of 29 mm +/- 1 mm specs.

clear skies

Rich Sky:
Hi, your problem is the camera and backfocus.
Tell all about your setup, how your cmos is attached to the Rasa.
or provide your backfocus calculation for your equipment and setup.
The circle is created by light beyond focus. The spot is an image of your clear glass located in the optical train, normal if the cmos is not exactly at the required backfocus of 29 mm +/- 1 mm specs.

clear skies

Given the other responses so far, and the nature of the spot itself, this seems like the best path to pursue. I was trying to figure out what would make the spot with that particular shading...it does not look like any kind of dust spot I've ever encountered, even with mis-correction from flats.

Rich Sky:
Hi, your problem is the camera and backfocus.
Tell all about your setup, how your cmos is attached to the Rasa.
or provide your backfocus calculation for your equipment and setup.
The circle is created by light beyond focus. The spot is an image of your clear glass located in the optical train, normal if the cmos is not exactly at the required backfocus of 29 mm +/- 1 mm specs.

clear skies

*** It's an ASI2600mc threaded to a Baader 7.5mm spacer then attached to the rasa with the stock retaining system. I was getting pretty great results even though I could see a little bit of backfocus and possibly a tiny bit of tilt. But then this started up on Feb.19th and I was completely lost.

ok, if you think the backfocus is correct, the problem could be with the cmos. is your cmos leaking oil, when was it purchased?
Your image shows the round spot but also different drastic gradient, not normal.

Good luck fixing this.

Rich Sky:
ok, if you think the backfocus is correct, the problem could be with the cmos. is your cmos leaking oil, when was it purchased?
Your image shows the round spot but also different drastic gradient, not normal.

Good luck fixing this.

**It was purchased in October I think. I checked the camera by using it on other scopes and the spot isnt there. I can also rotate the camera and the spot will hit a different part of the sensor meaning it's definitely on the rasa side.
The gradient within the spot made me wonder if part of the little lens group had shifted. Kinda like one side being farther from the sensor and one being closer affecting how well the light gets through.

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