Mystery FR/FF - does anyone recognise this?

[Avocette]

I bought this 0.8x Focal Reducer/ Field Flattener second hand in a ‘package deal’ without any specification details. I have searched for an image of one like it on various obvious websites without success so far. From the style and look of it my guess is that it is may be a clone of the units that Telescope Service or TS-Optics used to sell. It has an M42/T/T2 thread on the ‘camera’ end and a tube exactly like a 2” eyepiece at the other end. There is an undercut on this tube also like eyepieces, and scratch evidence that it has been attached at some time to a typical two thumbscrew eyepiece holder like a Sky-Watcher one.

I did find a similar looking one advertised as a Lunt Optics FR/FR here https://agenaastro.com/lunt-solar-0-8x-reducer-field-flattener-with-m42-t-t2-thread-caa-rf.html and I note that this unit is said to be ‘compatible for f7 telescopes from 80mm to 130mm’.

A further item that came in the package deal was an 8mm thick M42/M42 spacer ring as shown with the label ‘For 80ED’.

Anyone care to shed some light on what I have purchased? 

 

 

[Laurieast]

http://apm-telescopes-englisch.shopgate.com/item/333635303531

Maybe? Best I can find doing a Google image search.

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Certainly, the main unit looks very similar, but there are differences in the position of the threads on the telescope side. Lunt seem to include adapters to fit their telescopes with screw threads and provide what looks like a compression ring 2” eyepiece holder. 

I am really seeking clarification about whether the FR/FF could be suitable for use with a WO 110/770 which my astronomy club owns!

[M40]

It looks like a TS Optics device, I have a similar 0.8x reducer.

[StevieDvd]

Looks like an Altair unit to me - but not the latest version.

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1 hour ago, M40 said:

It looks like a TS Optics device, I have a similar 0.8x reducer.

Does the ‘For 80ED’ spacer ring have anything to do with it in your example?

[Anthonyexmouth]

Surely just a specific adapter that changes the thread size, Probably the "for ED80" is just there to say its for some specific ed80 that had those threads. You'll just need whatever adpater it is that threads onto your drawtube and converts it to the FF/R

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I spotted this table on the Altair publicity (thanks @StevieDvd). I’m wondering if the FR/FF alone gives 55mm back spacing  and for the ED80 the spacer ring gives 55+8=63mm as listed. So were there other spacer rings available at the time of purchase (6mm for the ED102 and 6.5mm for the ED110)?

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40 minutes ago, Anthonyexmouth said:

Surely just a specific adapter that changes the thread size, Probably the "for ED80" is just there to say its for some specific ed80 that had those threads. You'll just need whatever adpater it is that threads onto your drawtube and converts it to the FF/R

Not quite since it is an 8mm thick solid spacer tube with M42 male thread on one side, M42 female thread the other. It fits on the camera thread end of the FR/FF. The threads on the other end of the FR/FF are around 50mm (possibly 2” or 50.8mm).

[Avocette]

I think I’ve made some further progress! This advert shows the FR/FF already with the (unmarked) spacer ring in place.

https://www.365astronomy.com/TS-2-PHOTOLINE-0.8x-Reducer-Field-Flattener-for-70mm-and-80mm-ED-Refractors-from-f-6-to-f-8

So it seems that with the 8mm spacer ring removed the FR/FF may be directly suitable for a 70mm ED refractor………