Hyperion 31 or 36

[Mr Noble]

I'm planning on moving to a 2" setup and having spent a few hours today reading lots of threads on this great site, I've pretty much settled on the idea of having a nice matching set of Hyperions.

I have a Celestron CPC 800 so it's F10.

Main question for you clever folks is as per the title. Will there be much difference between a 31 and 36mm Hyperion with an f10 2" setup? Would one be better than the other? Should I go for the 31mm and also have a 36+ Super Plossl for scanning and finding or will one of these give the max field achievable?

Also, I'm thinking that a set consisting of the 8mm, 13mm, 21mm and 31/36mm would be a perfect combo. Do you agree with that or suggest differently?

My only concern with the BHyp ep's is that I understand they are not parfocal across the range. Would this prove a big annoyance and make it worth considering a totally different range of ep's?

Really appreciate any feedback. Thank you.

GN

[damnut]

HI Mr Noble,

Both the 31 & 36mm are true 2" eyepieces. The Smaller hyperion are 1.25" but sit in the 2" diags, these ep's can convert to 2" by removing the first field lens, this however changes their focal length. I have a 10" sct as main scope and am true 2" throughout.

The hyperions are great ep's, but as a cost/size compromise I have 2" moonfish eps and barlow. But use hyperions on my 'fracs.

[Macavity]

There's not an *awful* lot of difference (subjectively, IMO!) between the True Field of the 2" 31mm Hyperion Aspheric and the standard Hyperion 24mm in 1.25" format. But it's anecdotal that the 24mm Hyperion is a "simpler" design than its siblings. I sense the 31mm Hyperion is the "better" eyepiece - To which the "Aspheric" quality may or may not contribute? <G> If you want to live a little more dangerously, get the 36mm... On the other hand, the longer focal length may be more demanding on the design, on scopes, slightly less versatile etc.

I use my Hyperion 31mm as a "work horse" - Can't really afford Panoptics etc. <G> I wouldn't say (perhaps echoing the above?) it is "orders of magnitude" better than the Moonfish type thing? I have a 32mm Moonfish - Ever-ready (outdoors!) as a 2" focusser plug. But more than adequate too...

The series 5...8...13...21...30-something etc. is (probably) designed in "Golden Ratio" - Favoured by Vixen, Baader, Teleview. Tried and tested! Choice on longer focal lengths is flexible though...

[damnut]

I am with Macavity, can't afford panoptics, 250mm F10 scope pretty undemanding on eps. And yes my eyepiece plug is a moonfish uw 30mm!.

Cheers

[Mr Noble]

Thanks for the replies guys.

So are you saying, damnut, that the hyperions are actually only 1.25inch ep's and that I'd be better spending my money on "proper" 2" eps? I was under the impression that the hypers are proper 2" and that they just lose 35% of their "seeing" fov when you use them in a 1.25" diagonal.

Sounds like the best choise for my entire EP set is possibly 8mm, 13mm, 21mm and the 36mm then. That, it sounds like, would give the best range of possible viewing in the smallest number of ep's. (I don't really like using barlows)

[John]

The Hyperion Aspheric 31 and 36mm are 2" eyepieces otherwise they could not deliver their 72 degree apparent field of view (AFoV). They do come with optional 1.25" barrels and when those are used the AFoV will drop the maximum that the smaller barrel format can deliver in those focal lengths, ie, around 53 degrees for the 31mm and 47 degrees for the 36mm.

The 24mm Hyperion is a 1.25" eyepiece that claims a 68 degree AFoV which would mean that it will be showing pretty much as much sky (ie: it's true field of view) as the 2" Hyperion Aspherics used in 1.25" mode do.

Hope that makes a little sense

[Macavity]

What more can one say. The 3.5 thru 24mm Hyperions are, of course, furnished with the 2" diameter "undercut" on the main barrel. I always use them in 2" mode anyway. It has always slightly worried me that in 1.25" mode they may "swing around", fall out etc. <G> In some cases, the lower seating 2" mode could collide with diagonal mirrors, not fit properly, etc. But I've been lucky, thus far.

[damnut]

All covered above, thanks chaps, saved my two finger typing :-)