Antares 12" Dob Stellarvue 10*60 finder Telrad Meade 25mm Plossl, Orion 10mm plossl, Celestron 6mm plossl, Paradigm 18mm,15mm,12mm, 8mm, Knight Owl 20mm, Shorty 2x barlow, Celeston Ultima 2x Catseye Triple Pack Collimation 4.5" Tasco 11TR Frankenscope 60mm Tasco 9TE-5 60mm Tasco 7T Oberwerk 12*60 binos
Quote:Can someone tell me the purpose of blackening the edges of your mirror? Will they ALL benefit from it?Thanks.
XT10 classic with premium optics Tri-knob CR2 focuserCatseye + Glatter collimation toolsStarBlast 4.5" & 6"Round Table PlatformTV EPs
Orion XT12i with Swayze-refigured primary & Protostar secondary
Televue NP101 refractor
William Optics Megrez 90 refractor
Universal Astronomics Deluxe Mounts
All MY reflectors are apochromatic. I am personally covered with infrared detectors and emit at 295 Kelvin, 24/7. If I were to recieve a spin entangled photon before you recieved its twin, MY photon would predict your photon's spin. Every time. MY family's lineage goes back over three billion years and has a whole branch of science devoted to studying it... The most Quotidian of observers
C10NGT, Z8, 150 Rumak, XLT 150, C6, C5, SW5 Newt, 4.5 Ball, C102GT, C90, ST80, A70LF; 15x70, 25x100; Burgess BV; Paracorr II; T6 2.5, XO 2.58/5.1, Ethos-SX 3.7, Delos 4.5, TV Plossl 7.4-26, BCO 10, Hutech HC 12.5, Sterling 12.5-25, ES100 14, CZJ H 16/25, CZJ O 16, M5k UWA 24, T5 31, Ultrascopic 35, Titan-II 40; Bino Pairs M5k UWA 6.7, Baader Zoom 8-24, M5k SWA 24, TV Plossl 26, RKE 28.7; Zooms NZ 2-4, NZ 3-6, Leica ASPH 8.9-17.8, Baader 8-24; Baader Zoom Barlow, VIP Barlow
Quote:It depends a lot on the design of the scope. The bevel is less of an issue in a solid tube OTA. In a truss dob, though, it is possible for light from an off-axis object (like the moon) to hit the bevel at an angle where it will reach the focuser.Also, there is no downside to blackening the bevel. It is easy to do with a chisel-tip marker, takes maybe 30 seconds once you have access to the mirror.Jarad
Quote:...I do NOT recommend darkening the bevel on a primary mirror for the above reasons.
Celestron 8SE Dobstuff 13.1": Swayze refigured Coulter mirror, 6 pt mirror cell (2 pt edge support) and CF focuser board made by me StarBlast 4.5 ST80/PortaMount II Zhumell 20x80/Oberwerk 15x70 on a Seronik-style tripod boom mount Hubble Optics 18 inch F/4 mirror.
AD10, NoName8, DS-16 with Spooner primary.
ES, Sterling, Parks, Baader, TV, GSO EP's and a lone Nagler.
Nikon, Celestron binos
20" homebuilt truss dob 6" watson refractor
Quote:Here's another way to look at it. A 2mm wide bevel on a 10" mirror presents an area of nearly 1,600mm^2, equal to a square patch of 40X40mm. Remember, that's a scattering, (usually) aluminized surface. This would be equivalent to at least 50 shiny, exposed screw/bolt heads on the inner tube wall, down near the primary. Would any discriminating amateur (or pro) tolerate that? We go through almost tortuous measures to lessen the impact of scattering sources less injurious than this.
Orion ED80 - AT Voyager with TNT,pier ext.,Vixon steel tray and Manny's mod.
Omni 120 cg4 with Orion pier ext. and RA drive, Binotron-27 (25mm & 17mm Sterlings)
Orion XT10(Original F/5) SkyStopper Equatorial Platform
Jason Constellation Model 311(Modified with 1.25"Crawford Machine focuser & rings)
Quote:I cut a ring from MDF backboard material then wrapped it with flocking paper. I drilled holes matching existing mirror cell bolts to place it securely in place.I used the mask with my old stock mirror to cover a mild TDE then I kept it with my premium mirror to redirect air flow across the mirror to reduce thermal boundary layer but I found out that the mask was creating too much turbulence and decided to remove it. Now my scope performs better without it.Jason
Celestron C11+EQ6, skywatcher /Zambuto 12"dob,watchhouse tracking platform, 16"/Zambuto lightbridge , Ethos's 6,8,10,13,17,21. Naglers 31,26. Lieca ash zoom, televue 2.5 powermate,2"2x powermate .Paracorr type2. Howie glatter 2" laser & Tublug. Lumicon 2" UHC, 03, H-Beta,Televue smoothies ( all of em) , Meade 4000 smoothies ( all of em). That'll do for now.
Quote:In my case, I did install a fan baffle and the ring mask I have shown in the earlier post in this thread. I used this setup for a while but I have not been happy with it. When I did some analysis, here is what I noticed:
1- I noticed some air was escaping around the fan. I did my best to cut a baffle with an almost perfect fit but the pressure building between the mirror and the fan was too high and managed to push air through crevices between the baffle and the scope.
2- As far as the air that was redirected across the mirror by the ring mask, it was causing too much air turbulence above the mirror surface. I can see that clearly by defocusing a bright star. When the fan in turned on then the “boiling” effect got too severe.
I ended up removing the baffle and the ring – back to the original scope setup – and things got better. The turbulence was minimal when the fan was turned on.
Quote:But then I constructed an annular baffle from black foam core and positioned it directly above the mirror clips. The baffle is snug tight against the inner wall of the OTA.
Quote:Recently I drilled a line of several lateral holes just above the edge of the primary, below the baffle. Hopefully this will allow the thermals to escape more easily from the solid-tube OTA and improve the image.
Quote:Of course, back on the topic of blackening mirror edges, an annular baffle would cover the bevel - and perhaps a TDE, if the baffle is wide enough - and negate any need for blackening the bevel.
Quote:I've never had an optics-damaging accident when removing, cleaning, etc. mirrors in my Newts. Never dropped an eyepiece. Never damaged a lens or mirror. You just need to be careful and aware of what you are doing and aware of your surroundings. No quick, hyper movements. Maybe cut back on the coffee beforehand. Enter a Zen-state of relaxed concentration. Mike
Quote:Gambling isn't a good analogy to driving, and driving isn't a good analogy to cleaning telescope mirrors. Among these situations, we have more and more control over the variables involved. In gambling, the outcome is mostly a matter of chance. In driving, we have more control over the outcome, but we cannot control the weather or the other drivers. For cleaning telecope mirrors or blackening mirror edges, unless something out-of-the-ordinary occurs - such as an asteriod strike or the house blowing up - we are pretty much in control of the entire situation, beginning to end.Mike
Quote:But then I constructed an annular baffle from black foam core and positioned it directly above the mirror clips. The baffle is snug tight against the inner wall of the OTA. This time I noticed a circular motion of the thermals in a de-focused star or planet. At least I was having some effect on the image - the boiling effect was replaced by a circular motion - showing that the thermals were being moved differently than without the baffle.
Quote:Gambling isn't a good analogy to driving, and driving isn't a good analogy to cleaning telescope mirrors. Among these situations, we have more and more control over the variables involved. In gambling, the outcome is mostly a matter of chance. In driving, we have more control over the outcome, but we cannot control the weather or the other drivers. For cleaning telecope mirrors or blackening mirror edges, unless something out-of-the-ordinary occurs - such as an asteriod strike or the house blowing up - we are pretty much in control of the entire situation, beginning to end.
10" F/4.7 Modified Skywatcher Reflector, 38mm Orion Q70, 17mm Modified Ultima LX, 10mm TeleVue Delos, 7mm Pentax XL.