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I recently bought a 2nd hand Lunt 50PT Ha (on a different platform). The vendor said he had only used it a handful of times since buying it and it shipped in the original box. It seems fine, focuses well (although I find the helical focuser a bit of a pain compared to crayfords). But it doesn't show any Ha features on the surface of the Sun!
Long story short, I completely opened up the pressure tuner and found a bizarre thing. Its well greased, there's no detritus (and it doesn't lose pressure). But there was only one O-ring in it?! The tuner itself has grooves for two o-rings and the video on Lunt's website (on how to replace o-rings) shows a tuner with two o-rings when it comes out. And they ship replacements in batches of two.
So I'm guessing that somehow the original scope shipped with only one o-ring fitted? (It wouldn't make sense for the vendor to have removed one?).
I'm hoping that's what it is, b/c then the inability to resolve Ha features may just be insufficient pressure building up? In which case, does anyone know where I can get these replacement o-rings please (Lunt's US website has them but that's only for shipping to the US)?
If it's not that, and the scope is only meant to have one o-ring, any ideas on the problem? The ring & tuner seem well greased.
(EDIT: in the meantime, the next time the sun comes out, I'm going to try moving the current o-ring from the higher groove to the lower groove in case that longer distance from the base is why the pressure isn't building up sufficiently?)
We have a fledgling Astronomical Society at my place of work and we're intending to have some telescopes available for colleagues to view the transit of Mercury in November. While the majority will use appropriate solar filters it would be good to have at least one set up for projection. However, we only have reflectors and Schmitt or Maksutov Cassegrain scopes among the members. I was considering buying a small refractor second hand to use for this but thought I'd ask for advice here first.
Which is the best type of scope to use for projection?
What do we need to look out for (overheating & fire risks for example)?
What is the best umbrella to protect kit from the inevitable deluge on the 11th November? ☔
I just try to show the beauty of the night sky, and again the possibilities with a smartphone. There are already better applications at the google play to make the night lapse easy. At first I used the Gif maker pro. It's a good app to edit the frames, before creating video, but you can't save the videos in good quality. Now I use the TimeLab app (same developer, as Intervalometer app), in the editing it has not so many options, but with this app you can save the videos in 4K too, or full HD. This video is 360 frames (each 30 sec exposition at ISO 800) Huawei P10 monochrome camera, Intervalometer app, TimeLab app. Pictures taken in Kleinwalsertal, Austria 2019. 09. 23-24. (The video is full HD, I don't know, why, but it doesn't run continuesly on my PC, when I watch that back on SGL. I hope, on your monitors you can enjoy it!)
Skywatcher HEQ5PRO Tripod and Extension pillar.
There are a few marks on the tripod legs but not really noticable, the eyepioece/spreader tray has paint flaking off
But could be cleaned and repainted, it didnt bother me, but I am lazy.
I am selling as its not getting used as it should be and I find I use the excuse that it takes to long to carry it out
and setup, but in reality I think I am just losing interest.
As it is a heavy object collection from TS25 (Hartlepool) is preferred.
But if a courier collection service is available buyer pays the costs and arranges pickup I am happy as long as money has been transfered. Also I am prepared to travel a reasonable distance to meet for exchange.
Price £400 ONO I will not split
I have been away from this forum from possibly July - I never find a lot of time to do anything these days, same to be able to relax reading and interacting Astronomy forums.
I asked here a few ideas about making a solar scope or modifying whatever I had and I was recommended to also see Solar Chat Forums and I did.
Thanks to solarchatforums I have been able to do something decent and here is what I have done so far - very slowly!
1. I purchased a second hand PST and replaced its ITF with Maier one from the US and it finally had a clear image coming through + moved Etalon screw to third position - all the usual thing everybody does [after I researched it]!
2. used a new SCT screw-on short focuser [used once or twice on a LX200 R Classic] and using Teflon tape I screwed the PST Etalon to the focuser and purchased a 2" adaptor to fit on Etalon.
3. then used a Chinese 2" to 1.25 and modified the 2" side socket taking internal ring off and making 3x 120° threaded holes and 3x nylon thumb screws and used that as an adaptor to fit the original PST eyepiece holder - strangely enough at present this adaptor is also used as a tilter ... until I buy a proper camera tilter
4. then fit the above eyepiece holder into the SCT focuser with 2" to 1.252 adaptor in it and screwed the whole Gold PST tube with Etalon in it and made a BETTER PST - see image
5. I also initially tried a 2.2x DSLR camera Lens magnifier in front of PST and it decently works too - so PST will be fine for full solar disk mainly and without the 0.5 angstrom - not forcibly needed, I am probably around 0.7 as it is!
6. more importantly, I decided to make my own 90mm solar scope using the above bits and pieces.
7. with the help of Solar Chat Forums [great guys with a lot of knowledge, some are professional - i.e. they know the optics mathematical details - which helps] I purchased a cheap Bresser AR90/900
8. the ONLY usable thing there ... is the main tube, a nice and thick tube - the rest is ALL plastic!!!
I dismounted all parts and saw tube shorter ... a bit too much ! - I could have saved ~6cm really as I went with original ideas, but forgot I was using a different telescope from my initial thoughts - silly me!
So, I added a 6cm extension - no problems there to reach the 20cm inward needed for the PST Etalon which has ~20cm FL
9. initially I used a Tuna Fish 100g tin to adapt the SCT focuser onto my AR152 and fit Etalon inside the focuser to get near the 20cm needed- lets call it Quark unit - which it is really!
It worked well, so I decided to add a second focuser to tune the Etalon ... getting back to AR90/900 ...
10. I was trying to avoid overspending, I could not afford to spend too much - then I remembered I had a unused AR102SX which in my mind I guessed ... the focuser should over AR90/900 and it did!
It just fits perfectly - then drilled three holes for the holding screws et-voila'
11. I purchased a second hand 75mn Baader D-ERF and fit it INSIDE the AR90 tube at about 20cm inside from the front air-spaced doublet lenses, as there are the usual internal rings soldered in and just sit on it and I have about 70mm aperture - i.e 70mm width from the D-ERF for photons to get through.
At that ~20cm distance from front lenses the beam is still very large - probably about 60-65mm - there is no heat in between - no need for air-escaping holes
12. when I have the time I will make a solar finder scope and fit it on the tube - not that is really needed - I usually use CDC to get there almost over The Sun [having an almost exact spot on the yard!] - then use my eye without eyepiece and look thourgh the PST eyepiece holder for solar shinging and centre the telescope over The Sun.
Well, it works well after tuning Etalon focuser correctly and then focusing/tuning Etalon etc. - the usual.
See some images - still learning imaging/processing and a lot more to learn about Solar ... a lot!
I will probably need to get a Power-mate 2.5x when I can afford it!
1st mod - without the original black box - it works so much better - better focusing and sharper viewing too.
This is the AR90/900 shorten tube with AR102SX focuser and adaptors to test it normally
This is complete with the Quark Unit on the right side
Since this image there have been some changing - do not use the revelation adaptor any more and added a 6cm 2" extension.
Here are some images: