Hyperion Zoom help

[nobbytate]

Hi all i have a 21mm and 13mm hyperions and read somewhere about swapping the smythe group from the 21mm to the zoom to make it a 12mm to4mm.

Has anyone tried this as i was thinking of buying the zoom.

Thanks John

[GazOC]

Never heard of this John, sounds interesting!!!

[nobbytate]

Hi all just found my own answer on cloudy nights forum.

Aparently you remove the 1.25 ring and replace it with the 2" ring then add the smythe group from the 21mm eyepiece to give you a 4/12mm zoom. Does seem pointless when you might as well barlow it in the first place. John

[Macavity]

I think, if you look at the optical design of Hyperions, the 21mm is a TAD different from the rest. The front elements may not be (I spectulate!) a "Smythe" - So I'm not really convinced by the "mix and match" idea, with THAT combo. Of course there are also the extension rings, which work [iMO] "passably well", if you want to vary the focal length. I must admit I NOW prefer to leave my Hyperions unopened - to dust etc. But nice idea...

OT Aside: ISTR (IMO and despite rumour) most Hyperions are fairly "naff" without the "Smythe" lenses ... EXCEPT for the 21mm, which apparently makes a reasonable 35mm 60 deg eyepiece. But I sold mine, so can't confirm the last...

I suspect the Zoom is of substantially different design... (wouldn't kick one out of bed though!)

[nobbytate]

It,s only the 24mm thats different to the others as the smythe group cannot be removed as far as i know.

John

[tinvek]

I suspect the Zoom is of substantially different design... (wouldn't kick one out of bed though!)

and what exactly do you need a zoom lens to look at when in bed ?

[calibos]

In fact its the Fine tuning rings that can't be used with the zoom. The Smythe lensed 1.25" portions from any in the range can be used on the Zoom. In fact one of the others in the range can definately be used to give a nice 2-8mm I believe. I am also sure I read somewhere that the Smythe lense from the 21 can be swapped onto a shorter focal length to give a very nice 14mm 85º AFOV IIRC.

Haven't had a chance to experiment since I heard all this because my scope has been in bits for months...not that the weather would have let me play much in those months anyway.

[Macavity]

and what exactly do you need a zoom lens to look at when in bed ?

Sorry, intended merely as a "merry quip", reflecting (onetime) student humour. FWIW, the fairly EXACT technical information re. the optical construction of Baader Hyperions eyepieces is "out there" for interested parties. Such things can be worth a look...

I sense randomly swapping "Smythe lenses" is not particularly advised.

Aside: Unfortunately I never seem quite to get the balance between being

a "respected guru" (LOL) and "one of the lads" on internet forums?