Surplus Shed 127/700mm RFT/Spotter
Posted 10 September 2008 - 03:09 PM
Iâ€™ve been away from Internet and CN access for this past summer. Somewhat belatedly, I can now share photos and information about my Surplus Shed 127/700 mm RFT prismatic spotting scope that was completed last May. Looking back at the ATM Forum archives, it seems that not much has been posted on scopes built with this lens. Surplus Shed now lists this objective as temporarily out of stock, so hopefully more of these excellent lenses will be available soon. I was also lucky enough to buy two pairs of 50 mm Porro-Abbe prisms here on CN classifieds. (Thanks again, Howard!) Two of the prisms were cemented together to make an oversized erecting system for the scope. Focusing is accomplished using a homemade helical focuser made from thick wall aluminum tubing and UHMW polyethylene. The components were assembled in a 5â€ aluminum tube, with a short length of 6â€ aluminum tubing serving as a glare/dew hood. The scope is a joy to use, and provides high contrast, sharp, wide field images. Used with a military surplus 38 mm Erfle eyepiece, it gives 18 x and a 3.5 degree field â€“ a space walk feeling for astronomical viewing. It also gives good images with the Garrett SWA eyepieces down to 20 mm focal length (35x). In bright sunlight (for terrestrial use) and excellent seeing, one can even get away with Barlowing the 20 mm SWA to give 70x. I was pleasantly surprised to find that although the glare stops were cut to allow illumination for 2â€ wide field eyepieces, there does not seem to be much contrast loss when using 1.25â€ eyepieces with a smaller field stop. The complete scope with large military surplus eyepiece weighs 13.5 lb. (6 kg).
Used terrestrially, the instrument is kind of a â€œspotting scope on steroidsâ€. It provides bright images in the evening; long after my 3â€ spotting scope is out of business. Dozens of visitors used this scope to get good (and safe) views of grizzly bears and other wildlife in Glacier National Park this summer.
I have other photos of construction details and will be glad to post more if there are questions. Five photos follow. â€“ Bill Blunk
Posted 10 September 2008 - 03:27 PM
Posted 10 September 2008 - 08:14 PM
Posted 11 September 2008 - 02:58 AM
What an excellent project. I would be interested in the full report about the construction of this scope. I can't stay of that SS website, thinking about all of the fun scope projects I could crate from their stock.
Posted 11 September 2008 - 03:00 AM
Great looking scope. Is the mount home made as well? how about that focuser? Is the tube made from PVC pipe?
Posted 11 September 2008 - 04:48 AM
I've made 3 so far. The 80x 400, 70 x 500 (guide scope) and the 102 x 600. All were good except the 80, had to change the objective cell for an adjustable one to get rid of coma. But that might have been misalignment in the assembly as it was the first one I made.
Posted 11 September 2008 - 10:36 AM
Anybody want to report on how their 120 f/5 Chinese scope performs?
Posted 11 September 2008 - 01:10 PM
The CA is not very noticable at the low power that I use with this scope. It is an f/5.5 achromat so the CA will be there at higher power. I use my 5" Meade refractor for higher power observing.
I see nice sharp views at the 30X with this scope. I use it to sweep the Milky Way and large objects like M45 ect. Lynn