Suitable Moon Filter for Televue Radian

[djpaul]

Hi

Just bought a 6mm Televue Radian ep, and found that my Meade series 4000 Moon Filter doesn't fit it

Do Televue use a different thread , if so can anyone advise on a moon filter that does fit the Radian ep's

Paul

[alan potts]

Paul,

Can't say I really understand that I have Radians though not the 6mm and my 1.25inch ND filter fits them and I am sure I used to use it in the 26mm Meade 4000 Plossl before I gave it away. They should be the same.

Alan

[ghostdance]

Just tested my 6mm Rad - all my Baader filters fit perfectly, and my sole Astronomik fits but does not screw all the way in. Perhaps your threads have slight damage?

[djpaul]

Hi

The threads look fine on the Radian

The only other Ep's i have are BST's and it screws in fine with all those 

It only goes on about half a turn instead of 3 or 4 turns 

Would it still focus okay only screwing in that far?

Paul

[RT65CB-SWL]

I use a 'fixed' and a 'variable' polarising filter with my 6mm Radian when I am observing the Moon.

The 'variable' filter is this type... ...purchased from Sky's the Limit.

http://www.skysthelimit.org.uk/telescope%20filters.html

(note: it cosists of three parts. (1x eyepiece holder & 2x polarisng filter). I do not use the eypiece holder when using with the Radian).

My other 1.25" L/P filters do not screw all the way in when I use my 6mm Radian the threads look ok

[ghostdance]

If your filter only screws in a maximum of half a turn, I'd be concerned that it may fall out in use. Whether focus would be affected I don't know but would think not. Do BST not do an ND or Moon filter? The Baader Neodymium would fit with your Radian, but is at a cost over a budget filter like the BST, or keep an eye out for a used one. I have the same BST polariser set as Philip btw (and don't use the holder either) - it fits fine. The variability can be useful although I don't use it much with the Radian. HTH.

[John]

I've used a number of different filter brands and they all seem to have a slightly different fit

[djpaul]

Hi

Well i hope to try out the Radian tonight at some point, just to see if its much better than my BST Ep's i have

Im hoping it gives me a shaper, more detailed view.

Paul

[John]

Hi

Well i hope to try out the Radian tonight at some point, just to see if its much better than my BST Ep's i have

Im hoping it gives me a shaper, more detailed view.

Paul

What scope will you be using it with ?

[djpaul]

Im using a Skywatcher 120ed

Paul

[John]

I've got a couple of Radians that I use with my ED120. They work very well

Mine are the 4mm and 3mm. I find that I need the eyecups 2 clicks in from the highest position - I don't wear glasses to observe. You may need to try the eyecup in a few differenct positions to find your "sweet spot"

[djpaul]

I actually found 2 clicks down was the right setting for me today .

Just holding the eyepiece to my eye with the pupil guide attached .

I also don't wear glasses

If i get on well with this i will be looking out for a 3mm , 4mm and 10mm and sell off the BST's

Paul

[YKSE]

I've used a number of different filter brands and they all seem to have a slightly different fit

John, from your experience, have you found any Baader sfuff (EPs, filters, adapters, rings etc) where the threads don't fit their own counter parts?

[John]

John, from your experience, have you found any Baader sfuff (EPs, filters, adapters, rings etc) where the threads don't fit their own counter parts?

Baader stuff is usually fine. The Hyperion FT rings fit my 2" Tele Vue barrels for example and I've had no problem fitting filters by Astronomik, Lumicon, Baader and Orion (USA) to the other end of the FT ring. I can't recall having any problems when I used a 1.25" Baader UHC-S and O-III filter with a number of eyepiece brands either.

There was an interesting thread on the Cloudynights forum recently discussing this and a manufacturer explained how difficult it is for the filter manufacturer deciding the tolerences to use on their threads. There will be an eyepiece somewhere which it won't fit well !

[YKSE]

Thanks John, that's what I had expected. The reasons are not very complicated to me as a design engineer.

To have good fit of threaded stuff, it's not only th nominal  diameter and pitch should fit, the tolerence plays important roles too. For many rebranded stuff (EPs or filters), most non-optical parts are out-sourced, with low cost as primary target, the tolerence is usually compromized. (My Skywatcher filter doesn't fit Skywatcher Aero that well, but, it fits well in a baader; and the Astronomik filter fits Aero or a Baader very well).

Astronomics and Lumincon are premium products with excellent quality. Baader with all their filters, adapters etc, has made the thread precision to their core business, because their modular T2 system replys heavily on all the related stuffs can be threaded together when needed. Many of their parts are not really new parts, just a difference combination of some parts, Baader saves its cost with very low inventory thanks to the modular system.