Towa 1-inch visual adapters for small refractors circa 1960s to 1980s
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What we have here are (3) vintage, 1968-1977 years Towa of Japan .965-inch eyepiece adapters, which will work on various 50mm to 80mm refractors. They will NOT work with any Japanese-made 80mm to 114mm reflectors nor any 76mm to 114mm schmidt-reflectors as the focusers on these units had slightly wider, single stage drawtubes that will be too large to accommodate these adapters offered.
Each visual adapter comes with its original setscrew.
** The last photo illustrates the (4) primary .965-inch adapters you would come across from small, Japanese-sourced telescopes from 1958-1980. Please note that adapters (A) and (B) are not included in this ad.
From left-to-right:
(A) M36 male threads with (3) setscrews (Carton, Royal Astro, Takahashi)
(B) M25 female threads with (2) setscrews (Towa all generations)
(C) M26 female threads with (1) setscrew (Towa early generations)
(D) M30 male threads with (1) setscrew (Towa-Vixen and post-1980 Hino Optical)
Note the EXACT, matching knurled texture and bevel present on example (A) and (D), which indicate shared manufacturing relationships. **
Now, in reference to the 1st photo, you will see (3) adapters. The one on the left is a rare male thread variant. The ones seen in the center and the right are the common female thread models.
Both of these adapters attach the same way to the small telescope and are used for the same purpose; to thread to the fast focus drawtube in the rack-and-pinion focuser. Without this piece, there is no possible way to attach your .965-inch diagonal, eyepiece, or barlow.
The adapters in the middle and right are from a 1972 Jason 311 Constellation and 1977 Bushnell Sky II 60mm refractors. This is the more common adapter you'll come across in which it used female threads to attach to the male threads on the drawtube. The female adapter-to-male drawtube attachment process were present on virtually all of Towa's 50mm, 60mm, and some 80mm refractors ever known (at least 1964 to 1993; later date when including Orion models).
However, there are (2) variants of these adapters and it is crucial to know that although they are both used on Towa-sourced refractors, they cannot be interchanged.
The female, single setscrew visual adapter is a M26. The female dual setscrew visual adapter is a M25. The dual setscrew adapter was the most common of all variants because it was used on the 2-stage rack-and-pinion focusers; those focusers which had a very long, recessed drawtube for "macro" or "fast focusing". Virtually ALL of Towa's equatorial 60mm to 80mm refractors (examples being the Sears Tower 60mm f/13.3, Tasco 17TR 80mm f/10, Jason 313 Discoverer 60mm f/15.2, and Jason 324 Saturn 80mm f/15) use the 2-setscrew variant because the macro drawtube is narrower than a standard .965-inch, single drawtube focuser. In fact, the adapter itself is ever so slightly increased in diameter on the eyepiece-accepting end (internal flange) so that they didn't have to introduce a new barrel size.
The single setscrew variant of this adapter will look as if it will be a perfect fit, but, in actuality, will be too wide. It will not mesh with the male threads of the macro drawtube; instead, it will glide right past them and remain loose.
Therefore, it is very important that you measure the diameter of your male or female drawtube threads PRIOR to buying these adapters. Towa was notorious for making different adapters for different generations of their otherwise mechanically-identical refractors.
If your small Japanese refractor has a dual-stage focuser, the adapters offered in this ad will not work with your telescope.
Going back to the 1st photo; the adapter on the left is unique and from the late 1960s (I cannot precisely pinpoint the year); and is the oldest generation of the Towa .965-inch adapter. These would be present on Towa-Carton and Towa-Apollo Labs collaborated small refractors. What makes this adapter unusual is the male threads. Nearly ALL Towa-built refractors have male threads on the drawtube accepting the female threads on the visual adapter. This one is a reverse design; the female threads of the drawtube accepting the male threads of the visual adapter.
This visual adapter only works on single-stage drawtubes, which was commonly incorporated on f600mm and f700mm small refractors. The focusers on these .965-inch class refractors had a wider drawtube because the converging light cone is more squat; introducing a smaller, recessed macro drawtube would readily introduce vignetting in low-medium magnifications. In past experiences, I have not found this M30 adapter on small refractors produced after 1975.
Each adapter is made of solid milled aluminum.
Each adapter weights right at 0.4 ounces.
All (3) of these adapters, to include their individual setscrew, are all original from Towa with no repairs or modifications. Physical condition is perfect on each; their threads are not marred or stripped and the cylinder form of each is true (no flat spots or punctures). The setscrew on each adapter threads perfectly and does not resist or wobble when being turned. Cosmetics are very excellent on the male-threaded adapter and and great cosmetics (excellent for their age) on the (2) female-threaded adapters. Each is ready for immediate installment and use on your applicable small refractor.
Happy to ship to anyone anywhere.
Each visual adapter comes with its original setscrew.
** The last photo illustrates the (4) primary .965-inch adapters you would come across from small, Japanese-sourced telescopes from 1958-1980. Please note that adapters (A) and (B) are not included in this ad.
From left-to-right:
(A) M36 male threads with (3) setscrews (Carton, Royal Astro, Takahashi)
(B) M25 female threads with (2) setscrews (Towa all generations)
(C) M26 female threads with (1) setscrew (Towa early generations)
(D) M30 male threads with (1) setscrew (Towa-Vixen and post-1980 Hino Optical)
Note the EXACT, matching knurled texture and bevel present on example (A) and (D), which indicate shared manufacturing relationships. **
Now, in reference to the 1st photo, you will see (3) adapters. The one on the left is a rare male thread variant. The ones seen in the center and the right are the common female thread models.
Both of these adapters attach the same way to the small telescope and are used for the same purpose; to thread to the fast focus drawtube in the rack-and-pinion focuser. Without this piece, there is no possible way to attach your .965-inch diagonal, eyepiece, or barlow.
The adapters in the middle and right are from a 1972 Jason 311 Constellation and 1977 Bushnell Sky II 60mm refractors. This is the more common adapter you'll come across in which it used female threads to attach to the male threads on the drawtube. The female adapter-to-male drawtube attachment process were present on virtually all of Towa's 50mm, 60mm, and some 80mm refractors ever known (at least 1964 to 1993; later date when including Orion models).
However, there are (2) variants of these adapters and it is crucial to know that although they are both used on Towa-sourced refractors, they cannot be interchanged.
The female, single setscrew visual adapter is a M26. The female dual setscrew visual adapter is a M25. The dual setscrew adapter was the most common of all variants because it was used on the 2-stage rack-and-pinion focusers; those focusers which had a very long, recessed drawtube for "macro" or "fast focusing". Virtually ALL of Towa's equatorial 60mm to 80mm refractors (examples being the Sears Tower 60mm f/13.3, Tasco 17TR 80mm f/10, Jason 313 Discoverer 60mm f/15.2, and Jason 324 Saturn 80mm f/15) use the 2-setscrew variant because the macro drawtube is narrower than a standard .965-inch, single drawtube focuser. In fact, the adapter itself is ever so slightly increased in diameter on the eyepiece-accepting end (internal flange) so that they didn't have to introduce a new barrel size.
The single setscrew variant of this adapter will look as if it will be a perfect fit, but, in actuality, will be too wide. It will not mesh with the male threads of the macro drawtube; instead, it will glide right past them and remain loose.
Therefore, it is very important that you measure the diameter of your male or female drawtube threads PRIOR to buying these adapters. Towa was notorious for making different adapters for different generations of their otherwise mechanically-identical refractors.
If your small Japanese refractor has a dual-stage focuser, the adapters offered in this ad will not work with your telescope.
Going back to the 1st photo; the adapter on the left is unique and from the late 1960s (I cannot precisely pinpoint the year); and is the oldest generation of the Towa .965-inch adapter. These would be present on Towa-Carton and Towa-Apollo Labs collaborated small refractors. What makes this adapter unusual is the male threads. Nearly ALL Towa-built refractors have male threads on the drawtube accepting the female threads on the visual adapter. This one is a reverse design; the female threads of the drawtube accepting the male threads of the visual adapter.
This visual adapter only works on single-stage drawtubes, which was commonly incorporated on f600mm and f700mm small refractors. The focusers on these .965-inch class refractors had a wider drawtube because the converging light cone is more squat; introducing a smaller, recessed macro drawtube would readily introduce vignetting in low-medium magnifications. In past experiences, I have not found this M30 adapter on small refractors produced after 1975.
Each adapter is made of solid milled aluminum.
Each adapter weights right at 0.4 ounces.
All (3) of these adapters, to include their individual setscrew, are all original from Towa with no repairs or modifications. Physical condition is perfect on each; their threads are not marred or stripped and the cylinder form of each is true (no flat spots or punctures). The setscrew on each adapter threads perfectly and does not resist or wobble when being turned. Cosmetics are very excellent on the male-threaded adapter and and great cosmetics (excellent for their age) on the (2) female-threaded adapters. Each is ready for immediate installment and use on your applicable small refractor.
Happy to ship to anyone anywhere.
