Hyperion Aspheric

[AWR]

Apologies for yet another EP thread!

I was reading Nicnac's thread about Hyperions and the 31mm Hyperion Aspheric was mentioned.

Baader Planetarium - Baader Hyperion Aspheric

Chris (Macavity) mentioned that it went well with a Mak 127 converted to 2".

Reading the description of the EP it also mentions that it comes with a 1.25" adapter:

The standard 2” barrel provides the full 72º field of view, and a special wide-field 1¼” barrel with a field stop of 1.265”(32mm) will extract the maximum field possible from 1.25” telescopes.

What does this mean? In particular how would I calculate my field of view? Would it be the same as if I converted the my Mak 127 to 2" (however I do that!)?

Many thanks

Andrew

[Macavity]

Heheh - Just Macavity making (MAK 127 advocacy) trouble again!

YES, the Hyperion Aspherics do come with a curved(!) 2" to 1.25" adaptor, which solves the problem of non-matching orifices(!) but can introduce some vignetting. To some extent you can "see round" the bend, but not QUITE the same as 2" adaptation / optical path.

Since I had begun a reply to your PM, here's the (rapid, non-secret!) text therin:

(I haven't discussed the field calculations etc. and others are WELCOME to chip in!)

Hi Andrew,

I think the main thing to know (and it took me a while! <G>) is that the MAK127 "back end" starts off with a so-called "T2" male thread. As you may know, this is a rather well-established, standard between a variety (Baader) optical accessories.

The other standard (for 2" diagonals etc.) is the SCT (Schmidt Cassgegrain Telescope?) thread. The cheapest way to explore the possibility of fitting a EXISTING SCT 2" diagonal to the S/W MAK is to get one of those T" -> SCT adapters from Steve/FLO:

Adaptors - Skywatcher Maksutov to SCT adapter

Another possibility is this thingie- from Teleskope Service in Germany:

Adapter vom Skywatcher Maksutov auf 2" - Teleskop-Express: DER Astroshop + Fotografie + Naturbeobachtung

The above discusses the PRINCIPAL of why all this works, despite contrary rumours!

Also, TS have their DEDICATED "Maxbrite" T2 diagonals, which was the solution I used - Though this is obviously the most expensive method(!):

T2 MAXBRIGHT Zenitspiegel - beidseitig T2 Anschluss - Teleskop-Express: DER Astroshop + Fotografie + Naturbeobachtung

Overall though, I feel it transforms the humble(?) MAK127 into a passable general purpose scope. It certainly improves the rigidity of the back end! You can e.g. use 2" eyepeices with 30mm + field stop (maybe 40mm?) i.e. allowing use of common 32mm 70 deg 2" eyepieces and significantly more "framing" field than a 32mm 1.25" Plossl etc.

Anyway, hope that's not too lengthy or thoroughly incomprehensible!

[AWR]

Thanks for that - not too lengthy and very comprehensible.

Improving the diagonal was already next on my list which is why my interest was piqued by your comment.

Andrew

(After writing the PM I realised I had further more general questions)

[AWR]

To clarify a few details for myself and in case anyone else is interested:

I've done some measuring, and the very first thread (nearest the mirror) is M45x1 and so can be adapted using adapters from FLO or TS to a SCT thread or a 2" EP holder.

The thread on the outside of the existing EP holder is M42x0.75 (called T2?) and could be attached directly to the diagonal suggested (as well as many other adapters).

Andrew

[John]

You might be interested in this recent review of the 36mm version of the Baader Aspheric:

Baader Planetarium 36mm Hyperion-Aspheric Modular Eyepiece - CN Report

It looks as if, with the 36mm at least, that using the 1.25" barrel vignettes the field of view somewhat (ie: you loose some of that wide field).

It's tough to get a wide field of view from a 127mm F/11.8 mak - the design doesnot really lend itself to low power, wide angle views.

John

[Macavity]

It's tough to get a wide field of view from a 127mm F/11.8 mak - the design does not really lend itself to low power, wide angle views.

I think, as ever John, ultimately the FAIREST statement.

Below are some CALCULATED MAK127 True fields for Baader Hyperions, set against a background of the Pleiades. ISTR, I based these on the quoted field stop values. Though, frankly (Andrew) I found that the 31mm Hyperion SUBJECTIVELY didn't show "hugely" wider fields than the 24mm - which I see you already have.

I think if you want to EXPERIMENT with this: Personally, I'd get the FLO Adapter, a budget 2" diagonal... then TRY e.g. the 36mm Asp Hyperion, a 32mm (80 Deg?!) Moonfish... a 35mm PAN? Though it is my finding that even "circle diagrams" can slightly mislead on the TRUE (sky) field of view!

I am still fairly happy with the Maxbright 35mm (sic) diagonal. It was expensive, but upgrades the (rather ) MAK backend, to something SOLID. It isn't as heavy as a full 2" diagonal and naturally FITS the MAK127 and the novel 2"/1.25" Hyperion noses like a glove!

Hey, this is no worse than "Aperture Fever" threads [teasing]

(And hopefully, as therein, we ALL still learn something?)

[AWR]

John, Chris,

Thanks for the advice - I'm certainly not going to rush into anything although I do want to upgrade the diagonal one way or the other.

Food for thought.

Andrew