Brian,
I have an extension for my camera as it would not focus in my scope. Would it be best to put the dew heater on this extension or is this a trial and error thing? Also, when you say a heater on "the objective", what are you referring to?
Aaron
Strange "artifact" on light images
Re: Strange "artifact" on light images
Hi Aaron,
Have you had the camera long? Have you successfully imaged with it and your Celestron 150? I have no experience with Newtonians so I can't be of much help there. Do you know if the anti-dew feature is on all the time or does it require a flick of a switch? Have you shown the light frame image to the people at Altair? It sure looks like dew to me.
Just in case you haven't imaged with this combination before, try imaging something terrestrial, preferably something a great distance away. If that is not possible then I'd recommend pointing it at the Moon which is nearly full now. To begin with turn the cooler off. See if you can get a good image of the Moon and then turn the cooler on. Give it some time.
How humid have the nights been for you? The times I've had problems with dew, the humidity has been "dripping wet", meaning that everything including the grass, the laptop computer, the telescope tube, everything has a thin layer of water.
Primarily the reason why I asked you to image something terrestrial is that I am a bit concerned that there is some degree of vignetting going on. Your camera has a full-frame sensor. If I am not wrong cameras like this need a "field flattener" in order to get good optical quality from edge to edge.
Brian
Have you had the camera long? Have you successfully imaged with it and your Celestron 150? I have no experience with Newtonians so I can't be of much help there. Do you know if the anti-dew feature is on all the time or does it require a flick of a switch? Have you shown the light frame image to the people at Altair? It sure looks like dew to me.
Just in case you haven't imaged with this combination before, try imaging something terrestrial, preferably something a great distance away. If that is not possible then I'd recommend pointing it at the Moon which is nearly full now. To begin with turn the cooler off. See if you can get a good image of the Moon and then turn the cooler on. Give it some time.
How humid have the nights been for you? The times I've had problems with dew, the humidity has been "dripping wet", meaning that everything including the grass, the laptop computer, the telescope tube, everything has a thin layer of water.
Primarily the reason why I asked you to image something terrestrial is that I am a bit concerned that there is some degree of vignetting going on. Your camera has a full-frame sensor. If I am not wrong cameras like this need a "field flattener" in order to get good optical quality from edge to edge.
Brian
Re: Strange "artifact" on light images
Aaron,
I think you are going to need to do a lot of experimenting in order to narrow down the problem.
I would begin with:
1. With the cooler off, see if you can image something terrestrial.
2. With the cooler off, see if you can image the Moon.
3. If all is OK up to this point, turn on the cooler going forward:
4. If the artifact should reappear, make note of the temperature and humidity. Pull the camera from the scope and shine a flashlight/torch at an oblique angle onto the sensor window. Do you see dew? If not then shine a light on your secondary mirror. Finally check the primary mirror. Be careful not to exhale on the optical surfaces. Dew can form that way too.
Brian
I think you are going to need to do a lot of experimenting in order to narrow down the problem.
I would begin with:
1. With the cooler off, see if you can image something terrestrial.
2. With the cooler off, see if you can image the Moon.
3. If all is OK up to this point, turn on the cooler going forward:
4. If the artifact should reappear, make note of the temperature and humidity. Pull the camera from the scope and shine a flashlight/torch at an oblique angle onto the sensor window. Do you see dew? If not then shine a light on your secondary mirror. Finally check the primary mirror. Be careful not to exhale on the optical surfaces. Dew can form that way too.
Brian
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alinderbaum
- Posts: 34
- Joined: Thu May 28, 2020 7:56 pm
Re: Strange "artifact" on light images
After inspecting the lens, it appears there is an issue with the lens. Maybe this is a small crack that led to the issue? The white line does not move when touch using a cotton q-tip and appears to be on the inside of the glass.
- Attachments
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- IMG_2671 (002).jpg (307.64 KiB) Viewed 4533 times
Re: Strange "artifact" on light images
Wow, that's a new camera? That scratch unto itself won't cause the artifact you see but it might be an attractant.
The dust on the sensor window is causing those "donuts" I saw on your flat frames.
Brian
The dust on the sensor window is causing those "donuts" I saw on your flat frames.
Brian
Re: Strange "artifact" on light images
Aaron,
Is the camera still under warranty? If you've got time before it expires I strongly urge you image something terrestrial just to see if you can get a decent image. It's a lot easier working things out when you can see what you are doing. Night time work requires familiarity with your equipment.
Brian
Is the camera still under warranty? If you've got time before it expires I strongly urge you image something terrestrial just to see if you can get a decent image. It's a lot easier working things out when you can see what you are doing. Night time work requires familiarity with your equipment.
Brian
Re: Strange "artifact" on light images
Aaron,
People on the forum may disagree with me but I just finished reading through your earlier posts. I see that you are just getting started. I think you made a wise choice for your first telescope but I am sorry to say, my friend, you chose a camera that is not entry level. You would be much better off with a $250 uncooled camera. They are commonly called guide cams. That will keep you busy for at least a year or more, and then as your experience grows you may find that you want to upgrade your camera and telescope. This is a multi-year endeavor. Knowledge will come in fits and spurts. Sometimes you'll want to give up and then there will be a breakthrough. There is reward ahead but it comes slowly. We've all been through it.
Brian
People on the forum may disagree with me but I just finished reading through your earlier posts. I see that you are just getting started. I think you made a wise choice for your first telescope but I am sorry to say, my friend, you chose a camera that is not entry level. You would be much better off with a $250 uncooled camera. They are commonly called guide cams. That will keep you busy for at least a year or more, and then as your experience grows you may find that you want to upgrade your camera and telescope. This is a multi-year endeavor. Knowledge will come in fits and spurts. Sometimes you'll want to give up and then there will be a breakthrough. There is reward ahead but it comes slowly. We've all been through it.
Brian
-
alinderbaum
- Posts: 34
- Joined: Thu May 28, 2020 7:56 pm
Re: Strange "artifact" on light images
Good points, Brian. I have been using a DSLR for about 7 months now and had a lot of constraints when it came to longevity of sessions - battery would die after about an hour and a half, it took 40 seconds for a 15s exposure to go to my laptop, and many other little things that impeded my progress. I cannot walk away form my rig, so time constraints were/are important to me. Yes, it is a challenging hobby I have come to learn (especially for us non-engineer types 
).
I do wish I would have gotten an 8inch scope instead of what was recommended to me. Another newbie in our club was in the same boat, but he started with an 8 inch and while I have gotten some really nice final images, you can tell the difference with his scope. Anyway, I have a few years left with this one and look forward to producing some great results.
I do appreciate yours and everyone else's insight. It is a challenge weeding through all of the opinions and figuring out what is beneficial in your situation. As a non-techy guy, and a sales person, I expect that when I plug something in, it will work as advertised....but we know that does not always happen! That is my biggest challenge.
Aaron
). I do wish I would have gotten an 8inch scope instead of what was recommended to me. Another newbie in our club was in the same boat, but he started with an 8 inch and while I have gotten some really nice final images, you can tell the difference with his scope. Anyway, I have a few years left with this one and look forward to producing some great results.
I do appreciate yours and everyone else's insight. It is a challenge weeding through all of the opinions and figuring out what is beneficial in your situation. As a non-techy guy, and a sales person, I expect that when I plug something in, it will work as advertised....but we know that does not always happen! That is my biggest challenge.
Aaron
Re: Strange "artifact" on light images
Aaron
https://www.firstlightoptics.com/batter ... -pack.html
Don't dwell on the 8" scope - I have one and it brings a different set of problems to the party. The least problematic scope for starting out is a refractor.
If the scratch is on the underside of the sensor window then you must have a case under warranty? The sensor window may be replaceable as a part. Contact the vendor.
Might be worth posting an image of the eyepiece end of the scope with camera and any extension tubes attached.
Dave
I have used a DSLR for astrophotography (Canon 600D) but did not run with the internal battery. I used a dummy battery with external PSU (had 2 dew controller ports as well) driven off 12V. Cost around £110.DSLR - battery would die after about an hour and a half
https://www.firstlightoptics.com/batter ... -pack.html
Something wrong there - a USB2 should transfer a 20Mb file in under 5s. Going through an unpowered hub perhaps? That must be fixable. The exposure length is irrelevant as the frame is always the same size for a given capture area.took 40 seconds for a 15s exposure to go to my laptop
Don't dwell on the 8" scope - I have one and it brings a different set of problems to the party. The least problematic scope for starting out is a refractor.
If the scratch is on the underside of the sensor window then you must have a case under warranty? The sensor window may be replaceable as a part. Contact the vendor.
Might be worth posting an image of the eyepiece end of the scope with camera and any extension tubes attached.
Dave
Re: Strange "artifact" on light images
Hi!
I don't know if you already did find the source of the oblong form? Just in case I also took a look at the FITS from your first posting and that form is in the DarkFrame.fits. Here what I did got out of it. Made it color so it's more visible.
It is there in all 3 color channels.
I don't know if you already did find the source of the oblong form? Just in case I also took a look at the FITS from your first posting and that form is in the DarkFrame.fits. Here what I did got out of it. Made it color so it's more visible.
It is there in all 3 color channels.
- Dark Frame.jpg (675.36 KiB) Viewed 4364 times