Do You Have the Dreaded RASA Ring?
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- Опубліковано 24 сер 2023
- Do you have a ring in your RASA data and for the life of you... Can't figure out what it is? Well, I'm here to show you how I fixed those dreaded RASA rings that once you see them, you will always see them until you do something to fix them.
- Наука та технологія
I'm thinking of buying a RASA 11, this info is gold, thanks !
Glad I could help... The data out of the RASA is wonderfully rich now and as you saw, the gradients are easier to handle even with my light-polluted skies... You can't beat the speed of this fast scope and with my full-frames sensor. The FOV is breathtaking!
I hope things go well with your decission to purchase one. You can't go wrong and with this fix, the data is the best I have gotten out of mine at the moment...
Great Job Jeff, and timely video! I have mentioned the rings a couple of times in my videos and your findings backup my thoughts on them. I have actually already purchased Musou Black IR Flocking sheet and paint to tackle my scopes. The order arrived a couple weeks ago and now just need to get on with the mods!
Dave, I didn't use anything other than some flock I got at Hobby Lobby... and those 3D printed parts I made to allow me to slip them in and out as needed. Hope you have as much success as I did with your efforts to removes these pain-in-the-butt rings that ruin the data... I just wish Celestron would have had more information on what these rings were from and how to fix them when I purchased the scope a little over 2 years ago... Now my RASA 11 is making the best imagery I have ever seen come out of it... One Very Happy Astro Camper!
Great stuff Jeff I've got the RASA 11 V1 & it came with the Baader filter drawer system which did cause the rings you speak of, I'm now using the stock Celestron adapter & as far as I can see I don't seem to suffer with them, but using it with an APSC sensor does cause a lot of vignetting which flats take care of. I will still probably flock mine anyway after watching this as every little helps although I do still suffer with some tilt to which I will be sourcing a tilt adapter at some point but I'm not to fussed about it right now.
Glad you liked the video. One of the reasons I purchased the Astro HuTech RASA 11 Adapter was to get a bigger hole to help with the vignette I had from my full-frames sensor I'm using with my RASA 11. You will always get some vignette with faster scopes just because of their design. You get a hot spot that falls off fast to the outer edges. What also helped me was making my flats a little hotter. I use NINA's Flat Wizard and use an extra 10% for the mean. This helps to even out the hot spot to the edges. Good luck with your rings... They can be hard to handle... CLear skies.
Lovely video Jeff! - I for one appreciate you going to the effort to share this mate, good on you!
I've done the same kind of fix on my own RASA11 but my rings aren't completely gone yet - maybe further work to be done hey as discussed via email!
Clear skies mate!
Thanks, Luke Slowly but surely you get those pesky ring(s)... Clear skies!
Thank you, Jeff, great video and very timely as I just finished a narrowband effort on my RASA 11" which clearly showed major RASA rings that I've never seen before. I saw Luke of Lukomatico had addressed the issue which is how I found you! I now know how to fix this, and am therefore wondering if I can purchase those two inserts (3d printed perhaps?) from you? You also mentioned "flocking paper" but as I'm new to the hobby am unsure where/how to purchase this material as well. Hope you can help, and thanks in advance.
Thanks, Timothy
The parts I 3D printed were for my IDAS RASA 11 Adaptor. If you have the same adaptor, then yes, I can print you the 2 parts I made for that adaptor. If you are using the supplied Celestron camera adaptor(s). Then these will not work with those parts. You can find the Flock or Felt here:
www.amazon.com/YaoHui-Adhesive-Sheets-Backing-Backed/dp/B0BYM5LQQZ/ref=sr_1_5?adgrpid=1337006702007014&dib=eyJ2IjoiMSJ9.52NBUdKtJpTk0uY7VmZIubJx7xV_w5gM3rqNa0Xvxu6EUmF6pQ8fqebdFDAe1ZsW2GsgiXRk0x6vyelUCE8bQa6T8jqY5fp6FB3tzOQ02CuQzuuVCjHt-5Gjt67SJAGYUX9DAyuCylxbZMXKZVa9Gp5tdq_A8lkhwmnnKg0g20hCl7PyC_qzcFeZsd9LBcWlwNFVfeLDpF-yN5m3LzqD00B5XI7BsHrkuNXaiFmX1XsZzjx-IO8UxYz3yUJlGWVJqs2glHuGGKQzE9EecxB06nHFvhhve-Xxfgwb6jCSnvY.rWamqYosX3VodDLoCcVbLkrMfIEmK1nJIUceGhqnPxU&dib_tag=se&hvadid=83562989670986&hvbmt=bp&hvdev=c&hvlocphy=104790&hvnetw=o&hvqmt=p&hvtargid=kwd-83563259039727%3Aloc-190&hydadcr=5300_10448130&keywords=sticky%2Bbacked%2Bfelt&qid=1708356603&sr=8-5&th=1
Sorry for the long link...
I see these rings in my sct images and it is most noticeable when I have stacked reducers. I am sure the extra threads and adapters involved contribute to reflection. I ordered a bunch of flocking material some time ago but have not taken the time yet to implement it and see the results. I would like to have seen an apples to apples comparison with a second capture of M51 instead of a different target. Good video though. I will be flocking everything I can in my image train and see if I can have similar good results.
KB, Just been having too much smoke to try M51 again. Seems like all of western Canada is on fire and has been since April of this year... Jetstream pulls the smoke right over me. All I have to put up with is the smell and I still have a home. Some aren't quite as lucky as I am and have lost everything. My hope is that as it gets cooler out. The fires will die down and I can get back to doing some good Astro work with the gear. Seems like its been over a year since I've seen cloud and smoke free skies. It will turn my way... eventually. ;-)
Your reflections might be between the reducer and the sensor. I have seem that happen before... Good luck with your fixes... Clear skies.
My Orion 6” has the same whenever I put my filter at the front of my image train which has a 1.1x coma corrector
ortizma I think what you might have is a reflection between the filter and the sensor. If you can, try putting the filter in a different spot in the optical train. Sometimes that will help...
I just got my RASA 11 in and had my first light last night. I don't see the rings on my images, but I think I see them in my calibration frames.
If you believe your calibration frames are the problem. Try stacking the lights only and see what happens. After having meesed with this for the better part of 2 years. I tried many things. Faster scopes need a hotter flat. I have been making mine with the mean at around 40,000. Anything lower and the flats don't work as well with my setup. Dark flats (bais) and darks I make with the sensor cover on the camera. I don't see how a dark or dark flat will have a ring unless your have a bad sensor. Then I had a friend that teaches Astronomy tell me that this is a problem that the larger observatories have with thier large fast scope. They needed to use a special black paint and apply it to anything near the light cone to keep the reflection to a minimum.
When you have an image that has been pre & post processed. Then stacked, as you do things like a background extraction and what ever else one would do. This is when you start to see the ring appear. I have seen some RASA setups that have the ring without even doing a thing to the data. When I went to a full frame sensor with my RASA 11. I had to get larger adapters to help fight vignette. This helped with the reflections to a point. they were still there but as you saw in the video. They were still present and hard to deal with. I believe you have a reflection issue that needs addressing.
Clear skies...
Thank you. I will try that and let you know.@@jeffrh
After spending alot of money for a RASA. Why does the end user have to *FIX* the telecope? This issue is unacceptable.
Aggreed, but in the end I had to try something and this is what I came up with...