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Louis D

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About Louis D

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    Red Dwarf

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    Texas, USA
  1. There are bunch of threads out there on Synta base mods. There's the milk jug washer mod that goes around the central bolt. I would probably replace the factory bearings and bearing surface with whatever you used on the altitude bearings.
  2. Back when I was regularly using my 15" truss Dob, I would use the laser to do rough alignment by getting the return laser beam to coincide as closely as possible with the outgoing laser beam on the secondary mirror (which is plainly visible from the back of the scope) while at the back of the scope. I would then use the Rigel Aline to tweak the collimation incrementally going back forth between the focuser and rear of the scope. This method obviously won't work for a solid tube telescope, though.
  3. I can't figure that out, either. The numbers from a digiscoping calculator indicate that until I get to an 8mm eyepiece, there is no decrease from the camera's f/2.4 native f-ratio for the 127 Mak and 3.5mm for the refractor. And yet, eyepiece for eyepiece, I'm seeing more pronounced SAEP in the f/12 Mak than in the f/6 refractor. However, the effective f-ratio remains f/2.4 for both.
  4. All up, excluding VAT but including shipping, that's well over $250 for the focuser, adapter, and extension. I only paid $200 for each of my used 127mm Maks. I'll probably take a hard pass on adding one to either of my scopes. Thanks for the information, though.
  5. It's because of the slow f-ratio of the scope combined with the slow f-ratio of the camera. My Galaxy S7 camera is faster and picks up less of the SAEP in comparison. It mostly shows fleeting shadows instead of donuts. In my AT72ED f/6 refractor, some of the worst offenders show SAEP with the slow camera and only the worst of the worst show it in the faster camera. The analogous situation for the slow camera would be daytime, solar, or lunar observing where the eye's pupil constricts significantly, blocking more midfield rays as @Ruud shows quite clearly in this animation: At night, with a fully dilated pupil, SAEP becomes much less problematic. Camera-eyepiece spacing was at the exact point the full field stop came into view. Obviously, pushing in further reveals blackouts, but not of the SAEP type. Also, if you back off, you can avoid a lot of the SAEP as the two Meade MWA 26mm images show, but you lose some of the available field of view. Both situations are shown in another of @Ruud's excellent animations: Notice that it is edge rays, not midfield rays, that are truncated first in this situation. Neither being too close nor too far would show the black midfield rings I photographed. Some folks have complained about "finicky" exit pupils in the NT4s, Meade 4000 UWA 14mm, and the ES-92 12mm. I believe it is undiagnosed SAEP that has been causing it.
  6. It definitely matters at what f-ratio you test them. The NT5 16mm is pretty much immune to fast focal ratios compared to the UO and Celestron equivalents. At f/10, there's much less to separate them, though.
  7. I saw that link. I was surprised they didn't have the SCT adapter in stock since it would be the most common. What did they charge for the custom order when you bought yours?
  8. I took a bunch of photos of the fields of view (FOVs) of many of my 12mm+ eyepieces in my Orion (Synta) 127mm Mak using a 2" visual back and 2" diagonal using an LG G5 phone's superwide angle camera. This scope and camera combination really shows any spherical aberration of the exit pupil (SAEP). I composited together a bunch of the most interesting images with the worst SAEP offenders on the left and the best on the right. Rows are arranged by focal length, although I sometimes cheated and put interesting images on a nearby row to avoid the composite image getting too wide. I hope y'all find this interesting. It might help to explain why some people don't get on well with certain eyepieces. Shadowing is nascent SAEP. Rainbows indicate chromatic aberration of the exit pupil (CAEP). I had difficulty suppressing eye lens reflections on some of the Rini eyepieces, so they look kind of funky as a result. I included them because they are purely positive eyepiece designs that show lots of SAEP.
  9. Check your local library to see if they have a 3D printer available for use by card holders. My daughter used the one at our local library to print things for fun back in high school (8 years ago). I think there was a 4 inch cube size limit and one project per week limit. I would imagine they have an improved printer by now.
  10. As far as affordable UWAs, has any done a head to head between the Nirvana 16mm and the Luminos 15mm? The latter is considered one of the best of that line. I doubt I could use either with eyeglasses, so I'm out for comparing them. I'd be reporting all sorts of astigmatism across the entire field without eyeglasses.
  11. Too bad it's price makes the Noblex 12.5mm look affordable.
  12. Do you have the TS link for the SCT thread adapter? Thanks!
  13. Or just never sell and become an astro hoarder like me. I enjoy going back to compare newer acquisitions against older ones. My grown daughter also gets to borrow some really nice eyepieces without having to spend any money at all, so there is that as well.
  14. Could you link to a source for those little arms? I can't recall ever coming across them before, so I wouldn't know what search arguments to put into google to find one. Thanks!
  15. My Vixen LV 9mm always seemed to view a bit dark, but I never noticed any distinct color tone, although I never specifically went looking for it. Despite seeming a bit dark, it didn't seem to affect dim stars right at the edge of visibility relative to other eyepieces.
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