20 replies to this topic

[bekfromoz]

Hi all

 

as posted the other day I have recently been given a classic Towa telescope (thanks to all who helped me identify it!).

 

Everything I'd read told me it uses a 1.25 inch eyepiece. I just bought one, a Plossl 10mm, and it's too big. Does anyone know what size eyepiece tube/holder the Towa actually has? Are eyepieces for it available to purchase or is there some sort of adapter I might be able to get? Or am I screwed? All I currently have for it is a 20mm and even with the Barwon x2 lens all I get is a large but pretty much 2D image of the moon.

 

bek

[jragsdale]

How much smaller is the eyepiece holder on your scope? Just barely? Or quite a bit? The next step down is 0.965" and it's noticeably smaller.

Edited by jragsdale, 20 May 2025 - 08:46 PM.

[hboswell]

I thought the old Towas had .965" focusers? My old Tasco from the mid 80s (which I think was made by Towa) had a .965" focuser. If that's the case, you can get a .965-to1.25 adapter. I ended up replacing the focuser with a 1.25".

 

Harry

Edited by hboswell, 20 May 2025 - 08:44 PM.

[SoCalPaul]

I know they (used to) make hybrid diagonals that allowed the use of 0.965" eyepieces in a 1.25" receiver.

 

But it sounds like you need the reverse.

 

Can you return that eyepiece and hunt for one with a 0.965" barrel? Might be your best solution.

 

Clear skies,

Paul

[Elguen]

Looking at the pictures in the other post your telescope almost certainly uses .965" eyepieces, you can find the for pretty cheap on ebay.

[bekfromoz]

Thank you!

 

I shall begin the hunt.

[RichA]

Thank you!

 

I shall begin the hunt.

Just measure the aperture of the focuser, once you find it's 0.96" then there are eyepieces available.  But, you can also buy adapters to go from 1-1/4" to 0.96" and that opens up a much wider range of eyepieces for you.

[hboswell]

If you want to consider the possibility of replacing your focuser, one just showed up on Classified that should work for you: https://www.cloudyni...nian-first-gen/

[eye relief]

Orion 0.965-to-1.25 Eyepiece Adapter

 

High Point Scientific has an adaptor on clearance! Orion brand

[DouglasPaul]

My 2 cents; enlarging the hole to accommodate a 1.25 focuser can be a pain. The .965 to 1.25 adapter may take too much focus travel away resulting in the eyepiece not being able to focus. Best just to find .965 eyepieces, at least to start.

[SporadicGazer]

  ... Best just to find .965 eyepieces, at least to start. ...

Probably depends on your goals, I'd argue converting the focuser or a hybrid-diagonal work better though they're more complicated or not easily available these days.  For historic accuracy vintage 0.965" EPs would be best, though finding them can be hard.

 

There are a few new decent 24.5mm (=0.985") EPs available on Amazon Japan, so less complicated solution:

 

First 9, 14, & 18mm Plossls (labeled OR for orthoscopic, but they aren't Abbe's):

https://www.amazon.co.jp/dp/B01BIQD7S6

 

A 25mm Kelner:

https://www.amazon.c...n/dp/B01BQ0BPCE

 

And a 40mm AH (Achromatized Huygenian.  AH is to a Huygenian what a Kellner (AR) is to a Ramsden):

https://www.amazon.c.../dp/B01BQ0RNMU/

[RichA]

Also you can buy a hybrid diagonal for 1-1/4 eyepieces.

[DouglasPaul]

Probably depends on your goals, I'd argue converting the focuser or a hybrid-diagonal work better though they're more complicated or not easily available these days.  For historic accuracy vintage 0.965" EPs would be best, though finding them can be hard.

 

There are a few new decent 24.5mm (=0.985") EPs available on Amazon Japan, so less complicated solution:

 

First 9, 14, & 18mm Plossls (labeled OR for orthoscopic, but they aren't Abbe's):

https://www.amazon.co.jp/dp/B01BIQD7S6

 

A 25mm Kelner:

https://www.amazon.c...n/dp/B01BQ0BPCE

 

And a 40mm AH (Achromatized Huygenian.  AH is to a Huygenian what a Kellner (AR) is to a Ramsden):

https://www.amazon.c.../dp/B01BQ0RNMU/

 

 

Also you can buy a hybrid diagonal for 1-1/4 eyepieces.

I believe the scope is a Newtonian.

[hboswell]

The Towa is a Newtonian reflector, a diagonal isn't going to help.

[bekfromoz]

Thanks so much for all that info.

 

I'm in Austalia, which unfortunately complicates most of those options. The Orion adapter, for example, with shipping ends up at $140

 

I've sourced a cheap alstar adapter. Won't have it for a week, but will the quality just make it not worth it?

[RichA]

The Towa is a Newtonian reflector, a diagonal isn't going to help.

Makes it even more difficult, not likely having the focus draw of one of the old refractors.  

[hboswell]

Thanks so much for all that info.

 

I'm in Austalia, which unfortunately complicates most of those options. The Orion adapter, for example, with shipping ends up at $140

 

I've sourced a cheap alstar adapter. Won't have it for a week, but will the quality just make it not worth it?

These adapters are pretty basic so I would think it would be at least workable. Meanwhile keep an eye out for some decent .965" eyepieces, they do exist. I spent lots of fun nights with my Tasco/Towa 4.5" Newt years ago. Wish I still had it.

 

Harry

[bekfromoz]

These adapters are pretty basic so I would think it would be at least workable. Meanwhile keep an eye out for some decent .965" eyepieces, they do exist. I spent lots of fun nights with my Tasco/Towa 4.5" Newt years ago. Wish I still had it.

 

Harry

 

Thanks Harry. I really need all the encourgement I can get at this point. I want this to work so badly.

[ericb760]

Orion 0.965-to-1.25 Eyepiece Adapter

 

High Point Scientific has an adaptor on clearance! Orion brand

I bought one of those for a .965 refractor. It didn't come to focus with it in. I ended up buying a hybrid .965 to 1.25 diagonal that works perfectly but that won't help OP with a Newt. My vote is to replace the focuser with one like the post above linked to.

[DouglasPaul]

Thanks so much for all that info.

 

I'm in Austalia, which unfortunately complicates most of those options. The Orion adapter, for example, with shipping ends up at $140

 

I've sourced a cheap alstar adapter. Won't have it for a week, but will the quality just make it not worth it?

That's crazy, I wonder what it costs to ship a small box from the US there?

[SporadicGazer]

  ... I've sourced a cheap alstar adapter. Won't have it for a week, but will the quality just make it not worth it?

It shouldn't be a problem, these are very simple things and they'd almost have to try to screw one up.  (If fact I suspect there is one, or a very very few, factories spitting these out with only the silk-screen label changing per batch.  You'll probably get exactly the same as the recommended with the Orion label.)

 

OTOH- you will have a very unusual configuration if you can reach focus with the adapter as it add about an inch to the path and many focusers don't have that much extra range.  Good luck!

 

Also, it doesn't seem shipping from Amazon Japan to Australia would be any more than from Japan to the US so checkout decent (generic) Plossls in 24.5mm (0.965") I suggested above:

 

https://www.cloudyni.../#entry14144470