Last few nights I have experimented with some wide field telescopes on and off mounts instead of camera lenses, with extenders and focal reducers.The instruments used were the venerable and popular Orion ST80 80mm F/5 refractor with the ScopeStuff dual speed focuser, the 60mm Antares Versafinder
F/3.78 (bought from ScopeStuff), and my repurposed broken Orion 9x50 correct image finder. In all the viewing I used the Antilia 3.5nm Halpha filter.
To start off with, I showed M42 to my wife, who is not into astronomy, using the ST80 and x2 PowerMate. It filled the view (1.4 degrees) while still framing it, and she was very impressed. Just for giggles I then swapped in my 27mm Panopic with a Thousand Oaks OIII filter to see what an unintensified view would look like, and I could barely see any nebulosity in comparison. IC 434 was very prominent, the Horse Head easily seen; the Rosette Nebula very distinct and rose like with easily seen features.
I then tried using my Antares x0.7 and x0.5 focal reducers with the ST80. There was not enough travel with the ScopeStuff two speed Crayford focuser I had on it to bring the x0.7 to focus, but there was with the x0.5. I wanted to look at the various Auriga nebulae which were directly overhead, and thus not accessible with my Portamount (people talk of "Dobson's hole" but few mounts work well pointing straight up). So I took the ST80 off the mount and used it spyglass style, lying down, lockiing the focuser, and it worked very well. This combo weighs 1650 g, about 50% heavier than my heaviest eyepiece or largest binocular, but with two hands, and lying back it was quite handy.
The California Nebula was spectacular in both the ST80 w/reducer and the Versafinder (similar FOVs, 5.4 and 4.8), perhaps the most striking of all of the nebulas I viewed those nights with these instruments.
But all of these nebulas were quite prominent and showed detail:
M42/M43 (no surprise)
Running Man Nebula (Sh2-279)
Seagull Nebula (Sh2-292, Gum 1) [lower in the sky where it is brighter and more important has brightness variations, so this is notable]
Flaming Star Nebula (and associated nebulosities)
Sh2-171 and Ceb 214 in Cassiopeia
I had the Orion 50mm viewfinder on a Celestron C8 that toppled several years ago and the viewfinder hit the ground and snapped off the right angle eyepiece (but the C8 was fine). I saved the pieces thinking I would do something with them, and now I have. The 50mm plastic cap which had the right angle part broken off leaving a hole, which I enlarged with a Dremel to take a 1.25" tube. The Mod3 came to focus with the 1.25"-to-C adapter barely inserted in the hole, and adding a 0.75" spacer made it attach nicely. It is light and handy, and I will take it on trips with the Mod3 now.
It worked very well, and I could see all of the above in a wider field.
But what was most striking to me with all three instruments was how prominent both Barnard's Loop and the Eridanus Loop were. Though you cannot see the whole thing of either with any of these, you could see the band of the loop, with detail, and could trace the whole thing across 10 degrees of sky. Being able to actually see (rather than just detect) the Eridanus Loop was amazing.
The sky conditions may have been unusually good on the best two nights, pretty clear (but some cirrus in places), and we have been having Santa Ana winds, but apparently very transparent skies. This is supported by a third night when the nebulas did not seem quite so prominent.
The configurations successfully used were
ST80, FL 400mm, F/5 FOV 2.7 deg
ST80, Powermate x2, FL 800mm, F/10 FOV 1.4 deg
ST80, Powermate x4, FL 1600mm, F/20 FOV 0.7 deg
ST80, x0.5 reducer, FL 200mm, F/2.5, FOV 5.4 deg
Versafinder 60mm, FL 227mm, F/3.78, FOV 4.8 deg
Orion 50mm finder body, FL 180mm, F/3.6, FOV 6.0 deg
Edited by careysub, 28 January 2022 - 09:56 PM.