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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? ☔
Skywatcher 80 ED DS-Pro outfit including matched flattener and motor focus. Now only £350
This kit gives you a great introduction to astronomy and imaging, which is why it's so popular. You can see details over at FLO but there is:
80 ED Ds-Pro OTA (Objective Lens Diameter: 80mm, Telescope Focal Length: 600mm, f/7.5)
SW Eyepiece (2"): 28mm
2”/50.8mm Di-Electric Star Diagonal
Dual-Speed 11:1 2” Crayford Focuser (Backlash-Free)
Supplied with Tube Rings & Mounting Plate - please note there is a longer black vixen type dovetail fitted, not the fancy new green short one you will see on the FLO site
SW motor focus and fitting kit - I've never used this, hence it's not fitted (more details over on FLO)
Dedicated SW 0.85x reducer/flattener (see FLO for more details)
Aluminium Carrying / Shipping Case
The RRP is over £720, so grab a bargain while you can.
Collection from Nottingham, or DHL for £20 (within UK)
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:
Can anyone identify which control box this is? Is it focusmaster? And does it run off robofocus driver in Indi lib as I cannot get a successful connection (in indi within ekos)
I bought a robofocus motor with this control box second hand.
I have faith with seller that hardware works as should.
I've tried other cables and USB ports too. The software (k stars) I use does do port search when connecting equipment..
Any help appreciated