Warning about GSO Ritchey-Chretien's Baffling ( RC resold under Orion, TS-Optics, .. )

[@DoctorRickOD]

Thank you for your hard work. I have an 8" RC I bought from OPT (I think made by GSO) about 20 months ago. It suffers from this problem, but only when I use a .67 focal reducer in combination with a full frame sensor. When the camera is closer to the scope, as is the case when a focal reducer is used, I can see the crescent of light leaking as you show at the 26 second mark in your video. This light is only visible around the edges where it would fall on the peripheral edges of a full frame sensor, but not a crop sensor, and that's exactly what my images show. Images from a full frame sensor show a bright ring of light all around the periphery, while images on a crop sensor show no such glare. I never knew why until now. Thank you. Of note; my baffle is in two screw together pieces, the front most baffle does angle inward as you suggest.

[@TheNarrowbandChannel]

You are going to have massive vignette with a 35mm sensor and the 0.67 focal reducer.

[@morrisroland3549]

I have a couple of friends who use two GSO RCs-12” and 16”. Both of them have for some time reported this same issue to the point where they will need to extend the baffle. They say that the problem is present even when there are no bright sources such as the moon nearby. This is a fairly serious design flaw which I hope GSO will quickly address. Roland.

[@jcluque]

Wow, thanks! Excellent description. I own a TPO 10” truss RC as well, it’s manufactured by GSO. And I’ve noticed that flat frames are problematic. Please share how to fix the issue or measurements to print an extension baffle. Keep up the good work! Juan Luque, MD

[@Astrofrank]

The light ray from 2:14 seems to affect the image of most telescopes with a primary baffle, just shift the ray a bit downwards and it will go through the *centre* of the front of the baffle. One solution would be baffles within the baffle tube and drawtube, another using velours or anti-reflex paint on the inside of them.

[@siriusfritz4003]

Great video! I had 3D printed an extended baffle with a length thru trial and error and it transformed my flats/image quality. Excited to see your future videos!

[@meademods6024]

what did you do to correct the issue? the poster did not say where to buy the 3d printed baffle to correct the issue?? please see my post .

[@siriusfritz4003]

​​⁠I modeled and printed my own at first which was alright. Then I used this one, painted flat black, and reduced issue significantly. My last issue was reflections in my focuser so I fixed that with felt lining. Now I can take flats like a normal person with ease (ASI6200). Can’t post the link here for the final one I use, but go to Thingiverse and then search “RC-10 Baffle”

[@siriusfritz4003]

​​⁠​​⁠I modeled and printed my own at first which was alright. Then I used this one, painted flat black, and reduced issue significantly. My last issue was reflections in my focuser so I fixed that with felt lining. Now I can take flats like a normal person with ease (ASI6200). Go to Thingiverse and then search “RC-10 Baffle”

[@djtrackyard1833]

This is a very well researched video! Great presentation

[@bassaturdayobserving327]

Great information and research Leon. I have a 12" RC truss GSO telescope and would like to establish the length of the baffle needed. It measures about 305mm long from the flange inside te mirror with the outside diameter reducing in 2 steps at the open end. My flats don't show a distinctive bright ring. They gradually reduce in count towards the corner of the APS-C sensor as you would expect with vignetting. There is a slight darkening at the centre.

[@alexanderwagner9524]

Interesting video. I guess the "yellow line problem" only appears with open RCs because the wall of the outer tube will block that path on any of the affordable closed variants. Next time I take apart my 6" RC to clean the primary mirror, I will try to get a laserpointer to skip both mirrors and come out at the focal point of my camera. If that works, I will try to improve the baffle.

[@AntharikshamTV]

I am planning to buy GSO 8 inch RC . Are they still selling faulty Telescopes?

[@rodken314]

I have the GSO RC8 (carbon fibre tube) and the factory baffle is actually close to 200mm from the primary mirror and also the outer diameter tapers-in just like you see at 2:25. So GSO have fixed this problem for the GSO RC8 at least from early 2020 when I bought it new. They definitely changed the baffle when I compare it with a 2013 KZbin video kzbin.info/www/bejne/rKnZmpidq7ahqZo of the same scope. I've had no problems with flats, etc. Just make sure it is recently a recently manufactured scope or if from a shop inspect/measure the baffle. Actually I just noticed that TS says "Due to a redesign of the baffle tube, problems with stray light no longer occur". So means only the older 8 inch RC models need this fix.

[@AntharikshamTV]

@@rodken314 thank you for replying bro 🙂

[@LeonBewersdorff]

@@rodken314 Hi, I've read about this as well and it's great to hear that they're implementing changes, though I can't find anything similar for the other RCs - did you read anything? While the fix for the RC8 is nice, it's the telescope which is least affected by incorrect baffling either way (see description).

[@rodken314]

@@LeonBewersdorff Well, more recently, I purchased the RC10A (truss) and it needs the baffle extension; so it hasn't been fixed by GSO - the baffle is close to 203mm from the mirror. I'll be 3D printing a baffle extension this week. I've had light ingress problems with the RC10A so I was delighted with your video. The GSO new design "fix" for the RC8 seems overkill (longer) relative to your design at 198mm. I've had zero problems with the RC8.

[@TheCreeperCraft766]

Thanks for posting and for providing the necessary numbers. I'm designing a baffle extension for the 16" and am a bit confused by the numbers provided. From the video it seems as though your Y-value is a radial offset and not a diameter offset. If the Y-value is a radial offset, shouldn't the Y be doubled for designing the extension inward taper? For example, the inner diameter of the existing baffle for the 16" is 114mm. At the end of the extension, should the inner diameter be 107mm (1x Y) or 100mm (2x Y)?

[@markjohnston5234]

Very interesting idea. My flats show a pronounced plateau in the centre using an RC10 and APS-C sensor when plotted. Visually it looks like a bright centre region. I tried a quick experiment extending the primary baffle by approximately 50mm but sadly it made no difference at all. Also the diagram at 3:36 is confusing. It shows an APS-C sensor centred in the light path. A typical APS-C sensor is 23.6mm wide so the 15.73mm position shown within the sensor window is actually well outside the half width of just under 12mm. And for a full frame sensor of 36mm width, half width is 18mm which more closely matches the depicted sensor. 36mm from centre shown as the edge of the sensor is way beyond that size and is in the realms of larger format cameras not common astro-camera sizes.

[@thethirdman225]

I think GSO might have addressed this now. I could be wrong but I saw one recently and I believe it had that extended baffle.

[@edwardgill1042]

One other option to consider is an extended light/dew shield to reduce the more severe off-axis light rays and to protect the secondary from dew, easier to implement on the solid tube models. Nice work overall and I'm very interested in the improved baffling for the 16" GSO RC, we're operating remotely.

[@michaelaldan6969]

was thinking the same....

[@RichardKinch]

An external shield is basically an enlarged projection image of the geometry of the proper internal glare stop. Same principle as tulips on camera lenses, which have to be giant odd shapes to effectively stop all off-axis rays (but are needed because of front refractive elements; glare stops much precede optical elements). Better to just put the right shapes internally, where they're smaller, protected, and enclosed.

[@OzSteve]

Great video thank you. I am looking at buying the 16" Do you know if they've fixed the issue from your findings?

[@meademods6024]

I have the TPO aka (Third Planet Optics) 14" Truss RC from OPT their house brand. Does this scope have the same issue, and should I get the adapter to extend the baffle tube? Do you make them? thanks for the video and your work

[@lonoshamobservatory3556]

Can you confirm if this is also present on the RC8? If so, can you please create a 3d render for that model too? Very informative video, identifies the exact issue we've been having with our GSO RC8.

[@RichardKinch]

I have the Orion branded RC8 from 2017, which definitely exhibits this defect. Just perform a "live ray trace" inspection by moving your head around and looking into the entrance aperture in front of the scope. At certain off-axis points of view you can plainly see into the eyetube baffle extension directly, and then straight through to the 2in eyetube and out the exit aperture. So there are direct ray paths from the entrance off-axis, down the glare stop tubes, onto the camera sensor or eyepiece. Astonishing blundering failure of a glare stop design.

[@josephmcgee1454]

Thanks for your work on this video Leon! I've got a proto-type of an extension for my Orion RC 10" Truss tube printing right now. I plan to test it with a comparison of master flats. When I have the part refined I will share the stl file.

[@josephmcgee1454]

Test of flats showed a substantial improvement when the baffle was applied. An STL is now available on Thingiverse named as "RC-10 Baffle Extension". thing:5100741

[@ninthplanet3040]

I literally have a turned piece of aluminum in my lathe chuck waiting for the dimensions of the extension for the 16 inch telescope light baffle - the only specs that haven't been released yet. And they continue to be delayed. What's the issue?

[@LeonBewersdorff]

RC16 specifications have been added, I apologize for the wait.

[@ninthplanet3040]

@@LeonBewersdorff Thank you for discovering this and generating the results for all of us.

[@davidrowe9168]

Excellent video, well explained. -- Dave

[@KartikeyG]

In your video description, you mentioned that the RC8 is least affected by this problem, if I understand correctly?

[@sonnycavazos]

Thanks for the info! Do you happen to have the Blender or STL for the baffle extender? Would love to print it out for my RC10. Thanks again! Great video.

[@LeonBewersdorff]

Hi, the pure specifications for the baffles are listed in the video description, but I've also seen some finished ones posted on thingiverse. Of course I can't personally guarantee that these are correct.

[@a.ca.6832]

Hello, what about GSO's RC8 telescopes? Do they have that problem too? (it's the one I own)

[@marcoschafer4370]

He said in the description that it have this problem too but not as much as with the bigger scopes

[@RichardKinch]

The Orion-branded version of the GSO RC8 certainly exhibits the serious flaw.

[@a.ca.6832]

@@RichardKinch hello, mine is GSO, not Orion (Guan Sheng Optics) carbon-fiber tube.

[@massimo541]

Very interesting analysis, thanks! I am planning to buy a GSO RC8 Carbon and I don't know, since it's been two years, if this error has been corrected in the RC models currently sold. Do you have any updates on this? The information I have found so far is very conflicting, but I think the optical scheme with two hyperbolic mirrors is among the best. Since I do not have an observatory I thought of guiding with OAG and controlling the mount with an AsiAir. Do you think it is possible? Thank you for your attention, I have not found anyone who can give me some advice on this (I am little more than a newbie).

[@LeonBewersdorff]

Hi, I've also heard conflicting information on the new models. In more recent pictures I've seen of new RCs, the baffle was visibly not corrected. I haven't seen pictures of a corrected version either. I can recommend an OAG with a somewhat larger sensor over a guide telescope 🙂

[@kevinwhiteaker6474]

Thanks! Can you provide the detail design information you got from Teleskop Express? Did they provide the optical prescription on the mirrors, like ROC and conics? I have a GSO RC-8. I believe a longer outer baffle will help too. The scattering from the inner baffle is pretty bad. The threads are too small, and the coating is too reflective. Flat black paint can be difficult and expensive for such a long tube, outside and inside.

[@sknarberg]

Very nice work, thanks! I use a long dew shield for my TS 8" GSO, but wow this is shocking! GSO must know this, so why isn't it implemented?

[@LeonBewersdorff]

I don't know. I found a forum where the owner of Teleskop-Service mentioned years ago that he was already in communication with GSO about this, but nothing has changed in their production. This video also has 20 views from Taiwan where GSO makes these, so I'm assuming they've seen it as well. I also cannot know if this is truly the case, but especially on the RC8 the built-in baffling length seems somewhat arbitrarily chosen - it's exactly 15cm in length, and exactly 3cm off the optical axis. But with this baffling corrected the telescopes are nevertheless excellent in value, I use one myself.

[@sknarberg]

@@LeonBewersdorff, thanks and yes that's is strange. But good to know about the baffling being 3 cm off, that is considerable. I shoot with the ASI294MM Pro which has a 19x14 mm sensor, which makes ample room for additional baffling. I just need a 3D printer 🤣 I'm also very satisfied with the RC, best scope I've had. Also easy to collimate. Are you on Astrobin?

[@jPaulofe]

Great video and explanation Leon!! I have a RC6 for almost an year now, but as I was not happy with the results, I was thinking about selling it. Now I understand what's wrong and which are possible solutions for the problem, however I have a few doubts on how easy will be for me to implement a correct baffle/baffle extension and where to find those for a RC6. Thank you Cheers PauloF

[@thomaswicker4368]

Hi -- Very useful video. I have a 6" GSO RC and I'd like to implement your suggested upgrade by extending the baffling. You mention in the video that you will be publishing the information for 3D printing of the extension tube. Any idea when you might be able to do this? I have access to a 3D printer for the next 3 months, and I'd love to make one. Thanks VERY much in advance for your research and solutions. Clear skies!

[@LeonBewersdorff]

Hi Thomas, the information for 3D printing is in the video description. Clear skies to you as well! There haven't been many here lately

[@thomaswicker4368]

@@LeonBewersdorff Hi Leon -- Sorry to be dense, but I have no experience with 3D printing. I understand that the dimensions shown for the RC 6 above show how long the extension should be, and how much it should taper in but it seems like I would also need three other dimensions: overall extension diameter, thickness of extension walls, and where to begin taper ie does the taper run the entire length of the extension, or does it begin at some point up the extension? Again, sorry if I am asking dumb questions. Unfortunately, I don't have access to my telescope at the moment to make any measurements.

[@astromout]

Thank you so much! I'm buying an Omega 16'' (second hand) ...Could't you tell me what must be the length of the baffle for that optic? Second question where can I have the specifications of the telescope to make a simulation with my pupils :) Regards Franck

[@LeonBewersdorff]

Hi Franck, values are in the description. You can find the specifications online if you search for the RC mirrors by GSO on Teleskop-Service.

[@donaldmartin7109]

THANK YOU FOR POSTING. WOW VERY IMPORTANT. HAPPY SKYS AND HOLIDAYS.

[@oj5193]

Hello, great work! did you Design the 3d models of baffles extensions?

[@jwalters4681]

Thanks, I was just about to pull the trigger on an RC14. Do you happen to have or know where I can find an STL file for that one? Nothing on Thingverse

[@astrofenixsv]

Hello excellent video, I have seen that many use the so-called Flexible Dew Shield, I don't know if that avoids a little the parasitic lights that affect the telescope.

[@StarlancerAstro]

I don't see the RC6 mentioned, does it all suffer from this issue?

[@LeonBewersdorff]

Added to the description.

[@MichMak]

very interesting video. I've recently bought an RC8 from TS Optics (couple of months ago) and it came with an baffle extension, I wonder if this was there in the first place and further extension is needed or this is a "corrected version"

[@glennsubawalla9884]

i too bought a 8 in rc gso make telescope and it also has an extension on the primary baffle tube,i bought mu telescope in dec 21 , does it mean that the problem is fixed or do i need to do something more?

[@MichMak]

@@glennsubawalla9884 am not sure, I was hoping someone would come along with an older gso and compare

[@random2310]

Leon, are you still primarily doing photometry or astrometry? If so, are you still using a GSO RC or are you using something else?

[@LeonBewersdorff]

Hi, primarily yes. I still own the GSO RC but use other telescopes too.

[@taurus7228]

Hello. Any update from your side? I have been looking at a RC 8 model. Can you confirm whether the extension of the baffle completely fixed the stray light issue? Any other associated difficulty? Thank you Ashvn

[@globaloptics]

Fixed already.

[@lionki3]

​@@globaloptics You mean new scopes have already been factory fixed? All sizes or just the 8? Any idea after what date of manufacturer?

[@meademods6024]

you have not said where to buy the 3d printed baffling to correct the scope for imaging???

[@LeonBewersdorff]

There are multiple people who have designed baffles and/or sell them according to the values in the description. I of course don't know if they're correct, I haven't bought any.

[@TheNarrowbandChannel]

So where are the 3D printable models? I have a 10RC I would like to get one of these onto. Repeating my question because not one has answered it yet.

[@LeonBewersdorff]

Hi, the specifications for 3D printing are in the video description.

[@mildave5992]

Hi Leon, further to the supporting description to your KZbin video, I've now measured the primary baffle of my GSO 250 mm RC-Truss telescope. In doing so I find that the dimensions I get differ quite a bit from those you describe for the RC10. In my case they are as follows: - Inside diameter of primary baffle: 72 mm - Wall thickness at end of primary baffle 2 mm - Therefore outside diameter of primary baffle: 76 mm - Distance from mirror surface to end of primary baffle: 189.5 mm Some time ago I received a schematic diagram direct from GSO that with careful measurement appear to give the same dimensions that you detailed, but which are clearly different from my actual telescope. The remaining dimensions you specify do match-up nicely, however. My concern therefore is that there may not be "one size that fits all" in terms of specifying tertiary baffle dimensions. Unfortunately, I do not have the necessary ray trace modelling facility that you employed to compute my specific requirements or indeed to assess the baffle error of my system. I would be most grateful therefore if you would be prepared to run the numbers for my. I have also copied this observation on the ExoClock Slack channel for your convenience.

[@LeonBewersdorff]

Hi Dave, this seems to be correct. I relied on the diagram from GSO (sent to me by TS) being accurate for the raytracing. As you later pointed out in the Slack thread, the specifications given to me seem to be for the "RC10A" without any mention of how many differing versions exist. I have re-run it with your numbers and as expected, the issue persits. These new numbers only shift the incorrect edge by a very small amount, and not in the right direction. The description will be updated accordingly. Thanks!

[@dankuchta5170]

@@LeonBewersdorff ​@@LeonBewersdorff Hi Leon. Just wondering if the size of the extension has been updated in your description above. I have the same scope as Dave, with the same measurements. There's no indication in your description text as to whether the measurements have been updated or not. Also, what is the recommended way to attach an extension to the existing baffle. The Teleskop Express baffle reducer attaches to the outside with grub screws, but it looks like that could interfere with the light path to some degree.

[@LeonBewersdorff]

@@dankuchta5170 Hi Dan, yes, the extension sizes have all been updated and verified. The extension for the "other" measurements mentioned in Dave's comment were only shown for ~3 days after the videos release, only for the RC10, and also only differed by ~2mm. Since the diameter of the hole in the primary mirror is slightly larger than than the baffling, any screws or knobs which don't extend past the diameter of this hole won't have an affect on the light path. The TS screws appear short enough judging by the product pictures. For my own RC I requested a 3D print from a local printing company, who provided me a black baffle out of PETG. This baffle is on top of a cylinder which slides over the existing baffling and fits tightly, though I also secured it with non-reflective tape. The cylinder has a wall thickness of 2mm which is flat enough to not obstruct any further light.

[@wieslawpotoczek2715]

Excellent information! Could you please publish technical data for all these telescopes? I'm looking specifically for designed mirror distances for 8" and 12" GSO. Have found distance for 14" but nothing else. It would be nice to have other data for both mirrors ie. focal distances for each mirror in order someone want to repeat your calculations. :-)

[@LeonBewersdorff]

Hi, the pure specifications for the baffles are listed in the video description, and the technical data is available on teleskop-express: www.teleskop-express.de/shop/product_info.php/language/en/info/p2500_TS-Optics-Spiegelset-zum-Selbstbau-eines-10--f-8-RC-Teleskopes.html If the page isn't in English click the flag at the top right. The other versions are available under the same name (GSRCSetXX) in the search bar.

[@wieslawpotoczek2715]

@@LeonBewersdorff Hi Leon. Many thanks for your answer. Yes I found these drawings - in fact the only one on entire internet :-) The problem is that the drawings are incomplete and inaccurate. No focal distance for primary mirror is given - scale of the drawing is insufficient to take it from the drawing itself. The primary mirror diameter for my 12 truss is showing 304 mm where in reality it is 300 mm of active mirror only (the edge of mirror disk is "phased out" - so active reflection is 300 mm only). Anyway many thanks for your really good job with the issue.

[@alexanderdelpos572]

Hello, first of all I want to thank you for sharing the information. As I'm planning to create an extention for my RC6, I was wounderung if the inward correction (the 2.3mm) is for the radius or diameter? Please let me know. Thx!

[@ninthplanet3040]

Leon - according to your specs on the 16 in model, my light baffle length should be 351.5 mm (420 mm - 68.5 mm). My actual measurement is 347 mm. Thus, if I make my baffle extension 68.5 mm as you suggest, I will fall short of the target 420 mm by 4.5 mm. I'm inclined to make the extension longer that you recommend in order to get to 420 mm. Any thoughts?

[@LeonBewersdorff]

I think the difference is due to the measurement of 347mm being from the baffle edge to the primary mirror, whereas the measurement given in the description is measured from the absolute center of the primary mirror to the absolute center of the baffling, i.e. directly on the optical axis. Since the mirror is curved, these two measurements differ (they should by about 3mm).

[@arbit19]

Hi, many thanks for this. Now there is a solution to the maddening reflections! You also mention the tertiary baffle. Are there any details available on its dimensions and installation? Thanks

[@LeonBewersdorff]

Hi, I haven't designed any tertiary baffling as this is dependant on each telescope's focuser (and how it can be attached to it).

[@JohnRFreeman2]

Can you share the schematics that Teleskop Service sent you somewhere? I have a resin printer with a larger enough print area for the primary mirror tube baffle and have some thoughts on the tertiary baffling you mentioned.

[@LeonBewersdorff]

Hi John, sure, the schematics are available here, where GSO sells mirrors-only versions: www.teleskop-express.de/shop/product_info.php/language/en/info/p2500_TS-Optics-Spiegelset-zum-Selbstbau-eines-10--f-8-RC-Teleskopes.html If the page isn't in English click the flag at the top right. The other versions are available under the same name (GSRCSetXX) in the search bar. I've verified that these are the correct schematics for the fully assembled telescopes sold by GSO. If you print the baffling, I recommend adding small internal baffles (in the form of 1-2mm thick rings) to the primary mirror tube baffle to even better prevent internal reflections. I don't know how well different printers handle this fine detail. Let me know how the tertiary baffling works out.

[@JohnRFreeman2]

@@LeonBewersdorff Appreciate it. I've already printed tertiary baffling for my 16" going off of my best measurements using a caliper that I got two good nights of use off of ending yesterday. Today I'll start processing and seeing if my flats actually work. Flats not working was always super frustrating, and I couldn't figure out why something everyone seems to have no problem with want working for me until I watched your video.

[@JohnRFreeman2]

@@LeonBewersdorff It works really well. I ended up going with a series of baffles that sit inside the primary baffle tube. Each one is situated at 45 degrees, starting from the base of the tube and stacking on top of each other at the point the previous baffle ends; narrowest at the base and widest closest to the secondary, designed to be just outside of the on-axis light path. The final one is flat and has set screws in it to hold the entire baffling system in place. 18 total baffles. My flats finally correctly subtract! It's very exciting.

[@kamranashraf4982]

really a research grade advice ... thanks

[@torstenreinhardt7017]

Dear Leon. Great Video. I just bought an TS 8“ RC as the TS Website states that the issue with the baffle is now corrected. Are there any pictures available of the „old“ Design so I can compare it to mine? When looking through the focusser fully retracted, I still see a very tiny bit of light, coming directly from the aperture. However, when extending the focusser to resch focus, I cant see any light. I can see that there seems to be an extension on my baffle. I can Share pictures of my RC, if desired. Greetings.

[@LeonBewersdorff]

Hello Torsten, that sounds great. Please share pictures if you can, youtube sadly removes most comments if they contain links

[@torstenreinhardt7017]

@@LeonBewersdorff I have just created a Short video on KZbin with a view from the front and focusser, as my link was removed.

[@Hector_Malot]

It's really difficult if not impossible not to buy crap today when buying a telescope, especially for beginners. Unfortunately, in Astronomy as elsewhere, low prices are often synonymous with mediocre.

[@beatsntoons]

excellent video. Straight and to the point. Thanks for looking into this

[@whatmattersmost6725]

Hi all, just ordered a GSO RC6 and your video was about 2 years ago, could have GSO make a longer baffling already?

[@globaloptics]

YES. you got the new baffle design.

[@LeonBewersdorff]

Hi, could you provide a source for the measurements of the new baffle lengths? Were dimensions changed by GSO or are the resellers adding plastic baffles?

[@michaelklemm-abraham7298]

Dear Leon, Do you by any chance know: does the classic Cassegrain Design have the same problem? I do have the 6" classic Cassegrain by TS (also made by GSO, also sold under different brand names). I have not yet noticed any problems but I also didn't look for it since I only had very rare chances to use this telescope. Best, Michael

[@LeonBewersdorff]

Hi Michael, sadly I don't know, I haven't used SCTs from GSO (though my SCT from Celestron was fine) and I don't have any specifications for them. You can try looking through the optics (0:27) and checking for incoming light past the secondary

[@michaelklemm-abraham7298]

@@LeonBewersdorff Dear Leon, Just for clarification: I don’t meant SCT. I don’t even know if GSO have SCTs but classic Cassegrain designs (parabolic primary mirror and hyperbolic secondary vs hyperbolic primary and secondary on the RCs). Those do look pretty much the same, biggest difference is the classic Cassegrains are slower f/12 systems. Once I do have the chance I’ll check mine. Since the tube seems to be the same, the problem could be the same. Anyway. Thank you for your quick reply.

[@ewanancy]

@@michaelklemm-abraham7298 I can confirm that my 6" CC from Orion does have this problem.

[@AstroPilotchannel]

Does the Ioptron Photron RC6 have this problem as well?

[@LeonBewersdorff]

Hi, I've checked the optcorp.com website and it does look similar to the non-truss RCs GSO produces, but it would be best to write iOptron and ask where it was manufactured to be sure. You can also look through the end of the telescope (0:26) to determine whether you're able to look past the secondary.

[@Mistr_A]

wouldnt a dew shield over the front entrance work as well as a shroud for the open types? this helps prevent stray light

[@RichardKinch]

No, not as well, since the external shield is basically an enlarged projection image of the geometry of the proper internal glare stop. Same principle as tulips on camera lenses, which have to be giant odd shapes to effectively stop all off-axis rays. Better to just put the right shapes internally, where they're smaller, protected, and enclosed.

[@AlbinoTigerBarb]

Do you have one for the RC20? Many thanks!

[@LeonBewersdorff]

Hi, unfortunately, I don't have one for the RC20. I wasn't able to find specifications for it.

[@deltacx1059]

I'd just print a tube extension to deal with most of the bad stray light and maybe just add the baffles inside the existing primary baffle and/or just paint it with a even less reflective coating

[@donaldkasper8346]

What is the most interesting is that you contacted GSO and they refused to respond. I find this typical of many retailers of telescopes as well.

[@neilhankey2514]

These telescope are excellent for the money. Buld quality is great and are easily fixed by anyone with modest skills. Thanks for the information. I hadn't really noticed the issue, well nothing PI DBE couldn't fix! :-) But I will put my 3D printer to work and make the extension to the baffle.

[@freddyhtckomat]

Hallo grüße Sie. Ist es möglich eine blende bei dir zu bekommen? Aus dem 3D Drucker? LG Andreas

[@LeonBewersdorff]

Hallo, ich stelle die Blenden nicht selber her, ich gebe nur die Spezifikationen/Maße für die Blenden in der Beschreibung an. Es gibt aber online (z.B. auf thingiverse.com) fertige Blenden, die nach den Spezifikationen in der Beschreibung hergestellt wurden. Ich selber kann aber natürlich nicht garantieren, dass diese auch korrekt sind.

[@freddyhtckomat]

@@LeonBewersdorff ok vielen Dank dafür. Ist es möglich die genauen Maße zu bekommen? Dann kann ich ihn sicher wo anders drucken lassen. LG Andreas

[@Astrofrank]

Fun fact: I observed with a 12" classic Cassegrain for many years and even the moon wasn't really bad despite the telescope had no primary baffle tube at all, rendering it day-blind and reducing contrast when used with a front solar filter. Deep-sky photography wasn't a thing with f/20 and no possibility for guiding.

[@davidwhatever9041]

A superb piece of work, many thanks

[@RichardKinch]

In optical engineering texts and standards, the phenomenon is called "veiling glare", the theory is known as the "theory of stops", and the engineered features are called "glare stops". The best textbook I know is Smith's _Modern Optical Engineering_, and the Wikipedia article en.wikipedia.org/wiki/Veiling_glare is a summary. This blundering defect in the GSO products is astonishing. My Orion-branded RC8 was sold to me as being "fortified with 9 internal, computer-positioned knife-edge light baffles; and both the primary mirror tube and secondary mirror light shield are highly baffled to ensure maximum image contrast for bright images rich in detail." Maximum! If it were a car, we'd be expecting an NTSB recall.

[@MrProulx]

Very similar problems exist in telescopes in the 10-50k range also and beyond.

[@ASC-Explore]

Hi, any progress designing the baffling?

[@LeonBewersdorff]

Hi, the specifications for the baffles are listed in the video description.

[@Dudleydogg]

How can you tell which ones are made by GSO?

[@brainandforce]

All low-cost RCs are made by GSO. If you got it anywhere else, you (or your wallet) would definitely know.

[@Dudleydogg]

@ old post ended up with celestron

[@griffith500tvr]

TS-Optics does not give strehl information about their optics and since even a 16 inch f8 RC OTA only costs around €7000 I suspect that the optics aren't first rate.

[@maximecuypersph.d.2029]

thanks for this, i just bought a TPO RC10 carbon, does the baffling issue apply to this construct as well? thank you

[@LeonBewersdorff]

Hi Maxime, I've checked the optcorp.com website for the TPO listing but cannot find any mention of GSO. It would be best to write TPO or the re-seller and ask where it was manufactured.

[@maximecuypersph.d.2029]

@@LeonBewersdorff thanks for looking

[@maximecuypersph.d.2029]

@@LeonBewersdorff when i look through the rear aperture with all the 3' extensions placed, i can see the light. I guess my 10'RC TPO has the issue too.

[@ninthplanet3040]

@@LeonBewersdorff I purchased my TPO 16 inch f8 RC from OPT in the summer of 2016 and in discussions with them over the phone confirmed that GSO was indeed manufacturing their TPO brand telescopes, as I had a wait time for the shipment from China to reach California. I still have that telescope and am anxiously awaiting the results of this investigation. However, my concern is whether the specification diagrams provided by various distributors are consistent. I have found differing specifications regarding back focus, for example, from at least 3 big distributors of the very 16 in telescope I own. I don't know whom to believe.

[@maximecuypersph.d.2029]

@@ninthplanet3040 i saw a comment on a forum where a rolled piece of black paper is used as a baffle extension. I ll try that soon.

[@ss1204]

any data for RC6?

[@LeonBewersdorff]

Added to the description.

[@cemoguz2786]

We need people like you.

[@astroEnthusiast1]

Thank you! I honestly wanted to throw away my RC 308mm, astrograph! The images are awful, I'm struggling to achieve really good collimation. I working with the Howie Glatter collimator and it's not going well. But thanks for this video, more to add to the list of issues with the type of scope. I honestly would not recommend the older designed RC. The newer ones have separated the focuser from the primary mirror, which I sure everyone already knows by this time.

[@carlosgoti]

I have the same problem with an RC14. The images don't have espatial resolution. I have an collegue with an ESPRIT 150 with so far better images subs. I continue collimating but not solved yet. And also baffle problems...

[@nonjaninja4904]

Apparently Orion just slaps their brand on anything now. They should really include the baffle.

[@globaloptics]

I think the problem was solved a few years ago. when did you buy it?

[@entropytango5348]

One of the reasons I got rid of my GSO 6"F9 Cassegrain. GSO could learn a trick or 2 from Takahashi. My Mewlon is well baffled and no stray light.

[@szymonozimek5527]

Anyone have stl file for RC 12?

[@derekregan6926]

So is this just internal reflections and off axis light? If using open truss then I'd agree, but if you're using a solid tube 6, 8 or 10 then off axis light can't enter from the side as shown

[@LeonBewersdorff]

Hi Derek, the light enters at an angle through the aperture at the front of the telescope, not through the truss bars on the side of the telescope. See 02:08 - the red rays aren't far away from the secondary mirror.

[@derekregan6926]

@@LeonBewersdorff as i understand it, which maybe wrong but light entering from the front be contained by the baffles?

[@LeonBewersdorff]

@@derekregan6926 This is exactly the problem - it should be contained by the baffles, absolutely, but in the GSO RCs it isn't because the baffling length is incorrect.

[@derekregan6926]

@@LeonBewersdorff I sent your video to a friend with a GSO RC.. He's never had seen your issues and sent me a pic of the front of the scope and it has baffles all the way down

[@RichardKinch]

@@derekregan6926 The baffles are flawed. There is a direct path from off-axis rays into the eyetube.

[@ohwell2790]

Well, I am disappointed in my Orion CC 6 classical cassigrain to the point I no longer use it. I get better resolution in the term of arc seconds in my Orion ST 120, American Scientific AR 102, and even my Celestron 102 long tube telescopes. And I do know how to collimate the scope and the baffles are loose and rattle, will have to glue them in place ? The doubles in Lyra look like dog bones, in my refractors they are separated by darkness and are so round and bright. Pay your money and take your chances I guess. Will keep the CC 6 and see what I can do with it. I got it for the true colors where on my acromats just use a UV violet filter and all is fine.

[@ohwell2790]

Response to my previous post: After much thinking and watching how to's on U-Tube, finally have learned to collimate the C6. The images are beautiful and the time spent is well worth the effort. And as far as baffles are concerned have yet to see baffle's in a Newtonian telescope and they do just fine. I am just a visual observer.

[@terrance_huang]

isn't this just some matte black paint or light absorbing tape can easily solve?

[@LeonBewersdorff]

Hi, it isn’t. The off-axis light has a direct path to the sensor

[@geoffreyraleigh1674]

Thank you for the upload.

[@czar551]

Excellent, very informative. I actually noticed strange light strays on my OAG, I guess it was coming from off axis light. I have a 16“

[@SnaxxNZGaming]

My 8" RC (Purchased about a year ago) already has a baffle extension on it. Are you saying it need another extension?

[@LeonBewersdorff]

You can measure the baffling length from the primary mirror surface. If it's too short (see description), yes, you would then need an extension. Alternatively you've received a version where this has already been fixed.

[@SnaxxNZGaming]

@@LeonBewersdorff As far as I'm aware, GSO has been shipping their scopes with the extension for quite some time now (I bought mine 19 months ago and its got it). That's what confused me... This is a new video for a problem that seems to have been fixed quite some time ago. Its still relevant for older scopes, but there's no mention in the video that newer scopes already have the extension in them.

[@chuckf.6383]

Great work, thank you!!

[@michaelaldan6969]

that's some great astrodetective work my friend...well done!...i will call you Der Alte :) (you're a bit too young to know this great german detective series..look it up :) )

[@nmontec]

I agree that with that fix most of the issue is gone, but I noticed that working in bin 2 the issue comes out again.

[@TheNarrowbandChannel]

So where are the 3D printable models? I have a 10RC I would like to get one of these onto.

[@TeamAstroworkz]

been a known fix for a long time usually solved by some plastic rolled into a tube - a 3d printed version sounds better - did you make 3d printer files please?

[@starnunki]

👍🏻👍🏻👍🏻

[@Microtonal_Cats]

Any astro involving mirrors is held together with duct tape and hope.

[@nordic5490]

Or, wrap a piece of light block material around the outside of the truss.

[@paint_thinner]

that wont solve the issue as the light-leakage can come straight in the front avoiding the mirrors and any potential truss-cover.

[@PeterStaniforth]

Personally, I find all the "defects" with the vast majority of these precision instruments completely unacceptable. As usual, we are left with the only option of buying cheap quality equipment at not-so-cheap prices from China. When is some European or American company going to start making PROPER telescopes that are exactly what they should be "precision instruments" instead of us having to virtually rebuild or constantly tweak this garbage from China?

[@robertschmidli2195]

Apparently all the rc photos on axtrobin are flukes then.

[@robertschmidli2195]

All the pictures taken with these scopes are amazing and don't support this video unless your one of those people who have to screw with everything

[@Antiath]

As long as you don't make very long exposure, your flat will be able to correct properly. I noticed my flats were weird on my RC from GSO but I was able to get good images with good calibration while doing lrgb images. But recently I switched to narrow band imaging and had to raise the subs to 10 min single exposure. This made my flat completely unusable because the stray light became very present in the subs. But in a normal light polluted setting and doing LRGB imaging, you subs typically won't go past the 2-min mark, this makes things easier on that aspect.

[@TheNarrowbandChannel]

@@Antiath why are you taking 10min flats? even with narrowband images I take flats that are less than a second.

[@Antiath]

@@TheNarrowbandChannel I meant that I got leaked light on 10 min subs that no flat whatsoever could compensate for. But the flats were still short of course.

[@TheNarrowbandChannel]

@@Antiath Ok that makes more sense. I was going to say. 10min flats something wold be wrong. Way to many possibilities for light leaks or chanciness in conditions to get a good flat that way.

[@RichardKinch]

Understand that the problem is loss of contrast, not spatial resolution. If by "amazing" you mean spatial resolution, then that is not what is flawed.

[@a.ca.6832]

Hello, what about GSO's RC8 telescopes? Do they have that problem too? (it's the one I own)

[@RichardKinch]

The Orion-branded version of the GSO RC8 certainly exhibits the serious flaw.