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Everything posted by John

  1. This recent thread shows how popular RACI optical finders are. Often combined with an illiuminated reticule finder:
  2. Nothing wrong with 30, 40, 50 or more degrees of apparent field. Most plossl eyepieces have an apparent field of 50 or 52 degrees. Most orthoscopics have 40-42 degrees. Wide field designs offer 60-70 degrees, ultra-wides 80 / 82 degrees, hyper-wides 90+ degrees. It all depends on the view you want and how much you want to spend. Preferences have a lot to do with it. Budgets play a part in narrowing down what is available as well. The Hyperion eyepieces are 1.25" eyepieces with a 2 inch barrel section. You would use 1.25" filters with them. Many people find 60-70 degree eyepieces comfortable to observe with both in respect of the eye relief they, offer and the field of view being accessible. Some folks (like myself) also like ultra and hyper wide fields. Some are quite happy with 40-50 degrees but want it very sharp and well corrected. There are some decent quality zoom eyepieces available today as well - more options ! The market for eyepieces is even more complex than scopes these days - there are so many choices ! Sorry for the "scatter gun" answers !
  3. Thanks for the "heads up". A few years ago I visited the house in Bath, UK that Herschel was living in when he discovered Uranus. The house is now an excellent museum and well recommended for anyone visiting the lovely city of Bath https://herschelmuseum.org.uk/ I observed Uranus just last night as it happens. It showed a nice disk at 265x with my 12 inch dobsonian. I have glimpsed a couple of it's moons with that scope:
  4. I was quite impressed with the Vixen SLV's when I reviewed them for the forum. They don't offer a wider view than plossls though.
  5. You need to read this advice posted just yesterday:
  6. Ooops !! - I meant XL. That focal length never appeared in the XW range, they went to a 2 inch 30mm instead. Sorry about the confusion !
  7. The scope is very stable on that mount. I often use it on the Skytee II or Giro Ercole alt-azimuth mounts which are also very steady mounts for the F/9 scope. The dovetail bar is bolted to the clamp using M8 bolts so very strong. 95mm tube rings are another alternative but that size is hard to come by. Primaluce make some: https://www.firstlightoptics.com/tube-rings/primaluce-lab-95mm-plus-tube-rings-for-takahashi-fsq85-fs-78-fc-100df-and-fc-100dl.html
  8. You can tilt the focuser and objective cell by shimming with tape but having proper collimation adjustment makes life easier.
  9. Sounds like M31 to me. The eliptical fuzzy core is what we see unless the skies are really dark and transparent in which case it is possible to trace the galaxy further out from the core. In a low power field of view you should also see the small condensed fuzzy satellite galaxy of M32 and a little further out on the other side of M31, the much fainter small oval smudge of M110. Worth looking for when you next have a go at this object Messier 81 and 82 in Ursa Major are well worth checking out as well.
  10. Good stuff Jon ! Many of the lower cost refractors that I've owned have required colimation to some degree. I use a 2 stage process: focuser optical axis first (laser colimator for this) and once I'm happy with that, the tilt of the objective with the cheshire as you have done. Hopefully you will see some benefits in the views in due course
  11. I've got an FC100-DL (F/9) and it is very happy indeed on the Vixen GP which I think the EQ5 is cloned from. I've added a Vixen style DT bar to the Tak clamp:
  12. For visual astronomy, a good FPL-53 based doublet 102mm aperture refractor of around F/7 is a very versatile scope and relatively easy to mount and cart around. My Vixen ED102SS is mine (F/6.5 actually) and can range from a 4 degree true field for really large DSO's to a sharp 200x - 250x on the moon, planets and double stars. An AZ-4 mount will hold it well. Not sure that an F/11 (of whatever glass type) would be able to do all that
  13. Agreed - gentle scope tapping or wobbling is a good way to reveal a faint surface brightness target.
  14. I put one of the Skywatcher 1.25" dielectric diagonals on the Mak 90 that I had. That worked well: https://www.firstlightoptics.com/diagonals/SWdiagonal-20967.html or in StellaMira branding: https://www.firstlightoptics.com/diagonals/stellamira-1-25-90-di-electric-diagonal.html With a max AFoV 1.25 inch eyepiece I could get approx 1.3 degrees (minus any vignetting) which is about as much as I could hope for from a scope which is never going to be a wide field instrument.
  15. Excellent sketches Mark I was observing on and off (in tune with the cloud cover !) with my 12 inch dob last night and saw similar details for a while, which you have captured excellently. Those dark "promontories" sticking out into the paler areas were rather nice features last night. As you found, the seeing took a dive later and the surface features became much vaguer. I wondered if the south polar cap was actually a little larger last night than the last time I observed Mars ?
  16. Tonight was a bit frustrating here as well. I put my 12 inch dob out before supper under a clear sky. By the time I had finished eating we were heavily clouded and it even looked like rain, so the scope came back in. Then the cloud broke up and some clear patches arrived but it still looked dodgy so I used a lightweight refractor to peek in the gaps. Then more cloud so that scope came in. At 10:30 a larger clear spell seemed to have settled in so out went the 12 inch again. 30 minutes later I made the SN observations noted above, had some nice views of Mars and Uranus and then, more clouds piled in In, out, in out, just like the hokey cokey !
  17. Rather poorer transparency tonight but I have managed to see SN 2020uxz again. Using the 12 inch dob at 265x I can't get mag 14 or fainter stars due to a slightly milky sky. The SN is showing faintly where it did on the previous observation - I'd estimate around magnitude 13.5 perhaps ?. It is dimmer than a nearby mag 12.8 star but a touch easier to see than a mag 13.8 star that is mostly visible only with averted vision tonight. No sign at all of NGC 514 !
  18. Apologies to @Captain Magenta / Magnus for diverting this thread onto my particular issues. Thanks again for your interesting report
  19. Fair point but up until now I was really delighted with the 100 degree Ethos's in my F/5.3 scope. Come to think of it, nothing has actually changed with either the scope, the eyepieces or me so I guess I'll go on being happy with them
  20. Well, it was clear when I put the scope out before supper. Now solid cloud and looking like rain at any minute. Just bought the gear back in Silly hobby !
  21. 9x50 RACI optical and Rigel Quikfinder for me. Telrad would be fine instead but I wanted something lighter. RDF's are OK but the defined diameter circles of the Rigel and Telrad can really help with star hopping.
  22. When I had a 90mm mak recently I tried both the stock RDF and a 6x30 RACI optical finder (separately) on the scope. The optical finder was more effective (plus they are a more regular tool for me) but I felt that it didn't go with the very portable / compact scope package that I was after so I got on and used the RDF making sure that it was well aligned with the scope optics and managed OK with it. I don't actually have a straight through optical finder of any sort now because I much prefer RACI's.
  23. It's somewhere between FPL-51 and FPL-53 in terms of potential for CA control but remember that the glass used in the mating element plus the figure and polish of the lenses is equally important.
  24. So why am I not noticing coma ? I've been using Ethos eyepieces with this scope for over 5 years now. Without coma correction. I guess I thought I was a reasonably good observer. I'm beginning to wonder now .......
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