Orientation matters with the Chroma filters but I do not think that is your problem. Your arcs look like reflections. I posted a comment on the topic of Chroma filter orientation on Cloudy Nights with test results and images on the Star Capella with my new Chroma filters. Here is the link for the discussion. My comment is on line #76 on the 4th page. You can click on the photos to get a close up of the difference. Chroma 3nm orientation - Experienced Deep Sky Imaging - Cloudy Nights"First light on my new Chroma 3nm SHO filter set last night. I ran some tests on each filter and the results were the same on each. Placing the reflective side TOWARDS the camera is the correct orientation. On my filters that would be placing the TOP of the lettering towards the camera but it is better to check for the reflective/shadowing just to make sure. Here are two 3-minute subs with the Ha filter on the Star Capella with opposite orientations..." I hope this helps. Eddie
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I had an ESPRIT 120ED. I had no issue with an ASI1600MM (4/3” sensor). The arc were probably outside the sensor if they were happening at all. I upgraded to a full frame camera (QHY600M with 50mm chroma filters) and started getting those arcs. I tracked it down to reflections in the adapter between the flattener and the camera. After some reading at the time, I picked a method to breakup the reflections on the shinny surface of the adapter. (With everything separated :-) I painted the inside surface of the adapter with blackboard paint. Sprinkled the finest bits of seed on the surface and let it dry. (I forget the seed used but it was a suggestion someone made). I then did another coat of blackboard paint over that surface. The result was a very bumpy looking surface that must have bounced the light around enough to remove the hard semi circles.
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Greg McCall:
I had an ESPRIT 120ED. I had no issue with an ASI1600MM (4/3” sensor). The arc were probably outside the sensor if they were happening at all. I upgraded to a full frame camera (QHY600M with 50mm chroma filters) and started getting those arcs. I tracked it down to reflections in the adapter between the flattener and the camera. After some reading at the time, I picked a method to breakup the reflections on the shinny surface of the adapter. (With everything separated :-) I painted the inside surface of the adapter with blackboard paint. Sprinkled the finest bits of seed on the surface and let it dry. (I forget the seed used but it was a suggestion someone made). I then did another coat of blackboard paint over that surface. The result was a very bumpy looking surface that must have bounced the light around enough to remove the hard semi circles. I wonder does it happen with mirror-only scopes (Newton; RC; etc)? Thanks
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Just to add my two cents here.
I had the Esprit 120ED with the Esatto 3" and Arco, and I never experienced that. However, when I started with astrophotography, I got an APM 107, second hand from someone that claimed it was in good condition. When I received the scope everything looked great, so I mounted and I started to image, exactly at the same target as you showed as examples. I got exactly same artifact, and I tried to troubleshoot this. Long story short, one lens had a vey thin crack that was causing this type of arc when refracting the light coming from bright stars in and specially out of the field of view. How I found the crack, without the camera mounted, point the scope to a bright light, like a lamp at home, then move it to the side until the lamp is not directly seen through the scope looking from the side where you mount the camera. Then carefully inspect the lenses, I could spot a crack like this way. The scope had no easy/cheap reparation. I did learn a couple of lessons with this experience.
I really hope this is not your issue, but the artifact I had looks the same as what you have showed in these images.
CS
Obdulio
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hey Brent,
I have a 120 with the dedicated flattener.I have not experienced these arcs from the 120.Also I have 16"gso with the essatto focuser.This scope did produce arcs of stray light until I put an extension over the centre baffle.
Like wise with your 120 if you were to flock the baffle at the front of the telescope (120) and made up another baffle so as to slide it over the exsisting one this will definately reduce these problem arcs.At the same time be careful not to increase the vinyetting to much.
Best David
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Your arcs are reflections from a shiny surface, quite likely something anodized black but still smooth enough to cause a reflection for light at a glancing angle.
With the scope set up during the day, take the camera off and look into the backend carefully examining the edges of everything you can see between the camera and the front of the OTA. 10:1 you will spot something shiny that needs to be either flocked or painted matte black.
The tight radius of your arcs suggests the culprit is probably near the backend, quite close to the camera
One cuprit I found in my scope was the inside of the focuser barrel sleeve - right where you would normally slide a 2" barrel in, the inside surface was shiny and caused arcs from stars outside the frame of the camera.
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sounds like there is a post on CN that seems to find a resolution ? orientation of the Chroma filters "might" matter.. check it out : https://www.cloudynights.com/topic/715162-chroma-3nm-orientation/#entry10423985 |
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Eddie Bagwell:
Orientation matters with the Chroma filters but I do not think that is your problem. Your arcs look like reflections.
I posted a comment on the topic of Chroma filter orientation on Cloudy Nights with test results and images on the Star Capella with my new Chroma filters. Here is the link for the discussion. My comment is on line #76 on the 4th page. You can click on the photos to get a close up of the difference.
Chroma 3nm orientation - Experienced Deep Sky Imaging - Cloudy Nights
"First light on my new Chroma 3nm SHO filter set last night. I ran some tests on each filter and the results were the same on each. Placing the reflective side TOWARDS the camera is the correct orientation. On my filters that would be placing the TOP of the lettering towards the camera but it is better to check for the reflective/shadowing just to make sure. Here are two 3-minute subs with the Ha filter on the Star Capella with opposite orientations..."
I hope this helps.
Eddie I think you’re probably correct about the arcs of light being some sort of reflection, and not the filters being placed in upside down. The subtle pattern appearing around stars when the filter is upside down is substantially different than the huge, bright arcs I'm getting. I’m glad you did the filter-flip test so I don’t have to.  My observatory is 4 hours away so doing some quick tests ends up taking a couple days and a hotel room stay.
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Obdulio Garcia-Nicolas:
Just to add my two cents here.
I had the Esprit 120ED with the Esatto 3" and Arco, and I never experienced that. However, when I started with astrophotography, I got an APM 107, second hand from someone that claimed it was in good condition. When I received the scope everything looked great, so I mounted and I started to image, exactly at the same target as you showed as examples. I got exactly same artifact, and I tried to troubleshoot this. Long story short, one lens had a vey thin crack that was causing this type of arc when refracting the light coming from bright stars in and specially out of the field of view. How I found the crack, without the camera mounted, point the scope to a bright light, like a lamp at home, then move it to the side until the lamp is not directly seen through the scope looking from the side where you mount the camera. Then carefully inspect the lenses, I could spot a crack like this way. The scope had no easy/cheap reparation. I did learn a couple of lessons with this experience.
I really hope this is not your issue, but the artifact I had looks the same as what you have showed in these images.
CS
Obdulio Hi Obdulio, Thanks for the info! The crack in a lens sounds like a likely source of the arcs. ...but, I sure hope that's not the issue. Repair/replacement will put me my observatory out of commission for awhile. I'll try the method you suggested to look for a crack. Thanks for the suggestion! Brent
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Greg McCall:
I had an ESPRIT 120ED. I had no issue with an ASI1600MM (4/3” sensor). The arc were probably outside the sensor if they were happening at all. I upgraded to a full frame camera (QHY600M with 50mm chroma filters) and started getting those arcs. I tracked it down to reflections in the adapter between the flattener and the camera. After some reading at the time, I picked a method to breakup the reflections on the shinny surface of the adapter. (With everything separated :-) I painted the inside surface of the adapter with blackboard paint. Sprinkled the finest bits of seed on the surface and let it dry. (I forget the seed used but it was a suggestion someone made). I then did another coat of blackboard paint over that surface. The result was a very bumpy looking surface that must have bounced the light around enough to remove the hard semi circles. Hi Greg! Thanks for the info. What you're suggesting also sounds like it could be a culprit. That should be a fairly easy thing to check.
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Brent Bowen:
Greg McCall:
I had an ESPRIT 120ED. I had no issue with an ASI1600MM (4/3” sensor). The arc were probably outside the sensor if they were happening at all. I upgraded to a full frame camera (QHY600M with 50mm chroma filters) and started getting those arcs. I tracked it down to reflections in the adapter between the flattener and the camera. After some reading at the time, I picked a method to breakup the reflections on the shinny surface of the adapter. (With everything separated :-) I painted the inside surface of the adapter with blackboard paint. Sprinkled the finest bits of seed on the surface and let it dry. (I forget the seed used but it was a suggestion someone made). I then did another coat of blackboard paint over that surface. The result was a very bumpy looking surface that must have bounced the light around enough to remove the hard semi circles.
Hi Greg!
Thanks for the info. What you're suggesting also sounds like it could be a culprit. That should be a fairly easy thing to check. Even if you temporarily stuck some black felt on the inside of the tube between flattener and filter to see if reflection disappears
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