3" Japanese Refractor, Towa model 339
I remember lusting after one of these in the pages of Sky & Telescope but they were at the time, just too much money.
Late 70's to early 80's f/15 80mm refractor on an equatorial mount, a wonderful instrument with almost color free images and resolves to it's theoretical limit. These telescopes were produced by the Towa Optical Manufacturing Company of Japan and sold under various brands, here in Canada being marketed as the Tasco Model 10TE or 15TE and imported into the US by Meade as their Model 300 refractor.
And with an asynchronous AC motor drive as the Model 330, which was also a $40 option on the Model 300 and the Tasco's
AC drive finally found for this mount.
This instrument was found on consignment at Sean's Astronomy Shop
and shipped to my door by UPS. It arrived in almost pristine condition with very little wear and few scratches, still in the original packing and boxes. Reassembly went smoothly with not a part or screw missing and many parts still in their original wrappings. The objective had a fine layer of dust that was easily removed. The Lens is in a fully adjustable cell so the next step will be testing with a cheshire eyepiece followed by laser alignment and then a star test, the lens is coated on all four surfaces and no contaminants were seen between the elements. Obviously the telescope was hardly used and has spent most of it's existance in storage.This information was provided by John Siple, the seller:
"According to the data from the outside of the boxes, it was originally purchased in Seoul, South Korea. That was sometime in 1982. The individual obviously was in the military, and the scope was shipped back to the U.S.A. when he returned from overseas. When I purchased the instrument it was "brand new," meaning that the telescope had never even been taken out of its original wrappings and set up for observation. I basically purchased the telescope to test, and in the process handled the instrument with kid gloves. I used the scope a total of possibly five or six times, and then put it into safe, dry storage."
"I found the mechanical and optical performance to be excellent, with nice sharp, clean images. You would be hard pressed to get a scope in better condition than this one. Of all of the importers from Japan of that style of refractor, the Towa #339 was considered the best. I have looked through earlier versions and have found the one you now possess superior optically. Prices in the late 1970s averaged around $500 for the scope. To find one at $399 in basically unused condition is a rare feat! These often get heavily used."
Rose City Astronomer's newsletter with article by John Siple.
Unpacking and examination.
Eyepieces SR4mm, H6mm, H9mm, H12.5mm, Ke22mm
Original Manual.
Original Manual in Zip format (23MB).
Original Manual in PDF format (6 MB).
Tasco Instruction Manual.
Summary of first light, star test was done using Pollux and Castor, at 320X clean and round Airy disk observed,inside and outside focus identical, round and symmetrical. Contrast & resolution test on Saturn showed obvious Cassini division in the rings and one cloud band on the planet as well as shadow on the rings and the crepe ring at powers up to 160X. Original eypieces give surprisingly good performance and the Antares .965" plossls work well but the hybrid diagonal has misalignment problems, original .965" diagonal is well aligned and gives as sharp an image as straight through viewing. The 6x30 finder gives a sharp and bright image. With a new bulb and batteries, even the little tray light works. Best of all, no chromatic aberation or false color was seen.
Testing on the Moon up to 300X and still a nice sharp image, the huyghenian and symmetrical ramsden eyepieces actually do quite well at this focal ratio.
These older scopes have an elegant air to them.
Accessories:
Lumicon .965" to 1 1/4" adapter allows me to use my TV plossls with this scope, preferable to a hybrid diagonal.
University Optics Abbe Orthoscopic eyepieces to use for medium to high power, can't beat ortho's with these long fl scopes.
Baader solar film in cell.
A nice set of 1970's Optica B/C color .965" planetary filters.
2X achromatic barlow .965".
Prime focus and eyepiece projection .965" T adapter.
Modern plossl 0.965" eyepieces and hybrid 1 1/4" diagonal obtained from Antares through Island Eyepiece
Tasco #1605 dc stepper drive adapted to mount (same as Celestron drive for the CG-3 or Synta EQ2 mounts).
A little work was required to get the spring loaded clutch and the gears aligned. The mounting hub on the motor drive unit was designed for a 12.5mm stud and had to be opened up a little to accomodate the 13mm stud on the Towa. A 9/16" bit was used and the result was then cleaned up with 400 grit paper. The result was perfect fit and function.
2X to 4X drive speeds forward and reverse.
Observations with this telescope...
Tasco 1601-N camera adapter, adaptable to new and old camera setups.
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