My Spiratone spotting scope
Posted 30 October 2013 - 12:28 PM
I got my 50 year-old cat out of mothballs, and used the 35 mm. extension tube off my Lunt LS60T solar scope and the scope ring from my Canon "L" 100-400 mm. IS zoom telephoto lens to make a compact spotting scope.
The Spiratone cat is threaded for a T-mount. The Lunt 35 mm. extension tube is also T-mount threaded, and is the 1.25" eyepiece adapter for my solar scope. The cat was always a macro lens, focusing down to 1.7 m. The resultant hybrid spotting scope maintains that focusing range.
The cat performs better as a spotting scope than as a lens, perhaps because my visual standards are lower. With a nominal 62.5 mm. aperture and large central obstruction, the scope still easily surpasses the views through the standard Bushnell Spacemaster of the 1960s.
Posted 30 October 2013 - 12:31 PM
Posted 30 October 2013 - 01:38 PM
Just the kind of thing I may have come up with, had I the components at my disposal!
Posted 30 October 2013 - 05:19 PM
How much does it weigh?
I'll have to keep an eye out for an old catadioptric lens.
Posted 30 October 2013 - 09:23 PM
I paid $60 for the lens. I had the extension tube and eyepiece laying around the house, but similar eyepiece holding extension tubes are available for $15-$20.
Posted 31 October 2013 - 10:44 AM
Have you tried it for astronomy?
Posted 31 October 2013 - 07:03 PM
I was going to the post office, so I took the scope along. It weighs more than I thought - 1 lb., 10 oz.
Posted 01 November 2013 - 04:55 AM
Posted 01 November 2013 - 11:57 AM
Magnification varies with the eyepiece, according to the formula magnif=f.l./ep. Since the Spiratone is a 500mm lens, a 25mm ep gives 500/25 = 20x magnification. A 20mm ep = 25x, and a 10mm ep = 50x. The working range for terrestrial spotting scopes is usually 20-60x.
Posted 04 November 2013 - 04:26 PM