Circle T Japan 0.965"

[adictd2dalite]

Hi folks, I recently stumbled upon this set of SWIFT 0.965 eyepieces and I've done a bit of research but I was wondering if anybody could shed a bit more light on this matter for me please?

[michael.h.f.wilkinson]

The K designation stands for the Kelner design. These can be pretty decent. The AH I think is a Huygens or Huygens-like design, but I spotted some very positive comments on Cloudy Nights, listing as main drawback the rather narrow FOV

[adictd2dalite]

Hi Michael thank you for your response. Yeah it's an achromatic Huygenian. I think these could be from the 60s or 70s and perhaps made by Towa for Swift Optics but I'd like to know more. Having had a wee look at them the optics look so good I'm thinking of getting a 0.965 adaptor and hanging on to them.na

[A McEwan]

You can get a decent adapter on Amazon just now.

https://www.amazon.co.uk/gp/product/B08F9HQZ8N/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Ant

[Louis D]

5 hours ago, adictd2dalite said:

I think these could be from the 60s or 70s and perhaps made by Towa for Swift Optics but I'd like to know more.

The circle-T mark means Tani optical house.  They were best known for their volcano top orthoscopics sold through University Optics, Kokusai Kohki, and many others.

[SiriusB]

https://www.cloudynights.com/topic/465378-circle-t-towa-or-tany/

Loooks like Tani made eyepieces.~ see sketch in thread.

AH= achromatic huygenian i think?

I have corresponding 1.25" circle T Kellners,which i like.

You shouldn't lose any AFOV in the  12mm & 20mm & (maybe even 25mm?) in the smaller format compared to 1.25" versions.

😉

They look a nice set,~great for a classic refractor.

I've not seen volcano tops in .965" format, usually it's a (i don't have a name for the usual type of top in japanese .965")

[badhex]

On 25/02/2021 at 12:20, adictd2dalite said:

I was wondering if anybody could shed a bit more light on this matter for me please?

Bit late to the party on this one but might be able to add a little bit more detail. I have a couple of Swift 0.965 Kellners in 12mm and 20mm that came with the Charles Frank reflector I was given by my Grandad, so I spent a while trying to find out more about the EPs:

- As above they were made by Tani Optical and branded Swift - the light brown matches the Swift livery
- They were supplied with Swift refractors and probably also as additional accessories
- As well as the Kellners and Achromatic Huygens, they also had a few other designs, such as a 4mm Ortho, and 6mm and 20mm Huygens Mittenzwey (apparently the Mittenzwey variant reduced CA and increased FOV) 
- I *think* the Kellners and Achromatic Huygens may have actually only been additional accessories, due to the boxes and model codes (TA-1 etc) 
- Swift scopes seemed to have a wooden case with cutouts for EPs inside and pictures usually seem to be the other EP variants
- Swift and Charles Frank did some sort of collaboration at one point, offering Swift scopes on CF mounts - which may also mean that Swift EPs were available or supplied through Charles Frank in the UK
- There is a Swift owners registry over on Cloudy Nights with a ton of pictures worth having a peruse; page 11 has at least a few pics of the EPs  

https://www.cloudynights.com/topic/527598-swift-registry-reboot/page-11?hl= swift registry

Pretty sure I had some more info somewhere so I'll have a dig about, but hopefully the above is vaguely informative!