Hyperion owners. 1.25 or 2 in Diagonal ???

[Telescope40]

Hi All. I am currently using a 1.25 diagonal with my Hyperions. Am mulling over upgreading my diagonal to a 2in to make use of the 2 in option with these EP's. I have the 8 13 17 and 21 mm Hyperions.

Is this worthwhile. Nice improvment in FOV ?? or not worth the bother.

Scopes in use are a LX90 SCT F10 and C100 ED R F9

Any opinions either way most welcome.

Regards John

[John]

Hyperions are 1.25" eyepieces. The 2" fitting is a convenience but does not turn the eyepiece into a 2" one. Removing the 1.25" barrel with the lower lens assembly in gives you an eyepiece with a focal length of around 22mm but it's not a terribly good one to be honest. The exception is the 24mm Hyperion which does not have a lower lens set in the barrel, but that is still a 1.25" eyepiece.

[newman]

A 1.25" Hyperion only has 2" as an option for convenience. It is especially handy when you have some other strictly 2" ep's, then you switch to the hyperion and don't need to put on a 1.25" adapter but just slide it in the diagonal.

Optically, there's no difference. A 1.25" eyepiece is always a 1.25" eyepiece, even when it has provisions to be put in a 2" diagonal or focuser.

edit: John was faster. What he said

[Macavity]

I find a 2" diagonal - especially if it screws onto, or is otherwise "rigidly fixed" to the back end of the scope, adds a lot to the mechanical STABILITY of the setup. I have always been a bit circumspect about the large (top-heavy) weight of lenses, just waiting to "swing round" on a 1.25" diagonal. I'm convinced, but probably just a preference, or neurosis...

[Telescope40]

Cheers guys for your viewpoints. Think my credit card can relax for now.

Regards John

[damnut]

Hi Telescope40,

Get your credit card back out!, I have the LX200 10", and agree with comments above. However if you put a 2" diagonal on the back of your scope as it stands the stop on it will almost reduce the 2" to 1.25" anyway.

You need to get your hands on the Peterson 2" visual back for your scope then get a 2" diag and a 30 mm wide field of view ep. As our scopes are f10 then they are undemanding of ep's as such I have a 30mm & 42mm Moonfish and these give great wide angled fov.

The complete conversion of your Hyperions to 2" involves removing the field lens (the first lens in the 1.25" barrel) this leaves a proper 2"ep BUT the focal length is altered. My 5mm Hyperion becomes 17mm in true 2".

Some links below for you play with.

http://www.12dstring.me.uk/fov.htm

N.A.A. Telescope Math Calculator

Good Luck

[moriniboy]

I use my Hype 21mm with and without the 1.25" lower lens.

Rumour has it that it becomes a 31mm without and its not that different to my 36mm aspheric.