msrp:
$200
by
David Knisely
Wider-field
“budget” eyepieces seem to be all the rage these days.
Some are not all that great in the performance department (especially
in faster scopes), but once in a while, one comes by which sets
itself apart. Baader Planetarium now has a new entry in this class:
the 36mm Hyperion-Aspheric eyepiece, and this one seems to be one of
the better moderate-cost eyepieces I have run into lately.
The
36mm Hyperion Aspheric:
This eyepiece is a six-element wide field (72 degree Apparent field)
modest-sized 2” barrel ocular, with at least some of the
optical elements allegedly being non-spherical in nature. It is of a
fairly manageable size, being about four inches long by 2.5 inches
wide. The eyepiece has a hard low-profile rubber eye-cup, along
with a knurled rubber mid-section halfway down the eyepiece for
better gripping. The eye lens is about 28mm in diameter and is
recessed slightly in the rather shallow eye-cup. The eyepiece
weighs-in at a modest 410 grams (0.9 lb), so it isn't exactly a heavy
unit. The chrome barrel has the usual safety groove and is threaded
for standard 2” filters. The barrel also does unscrew,
allowing the eyepiece alone to screw into some SCT rear optical ports
when needed for imaging. The eye end is allegedly compatible with
some of the astigmatism-correcting systems for those who wear glasses
(not tested). The unit also comes with a rather unusual horn-like
1.25” screw-on adapter which lets one use the eyepiece in an
1.25” focuser, although the field of view becomes noticeably
more limited when this is done. With drift testing and a little
rough optical bench work, the following specifications were noted for
this eyepiece:
36mm
Hyperion-Aspheric Eyepiece Specifications
Dimensions:
4” x 2.5” (2” O.D. standard barrel).
Weight:
410 grams.
Eye
Lens Diameter:
28mm
Eye
Relief:
18mm
Measured
Apparent Field of View:
72.3 degrees.
Eyepiece
Field Stop Diameter:
44mm (31.5mm in 1.25” adapter mode)
The
eyepiece was a fairly solid unit, with no signs of looseness or
rattling when moved or shaken. All optical surfaces seem to be well
coated. The filter threads worked fairly well even with my
“problem” filter (Orion Skyglow, which doesn't like to
thread very far on any 2” eyepiece).
Performance:
I tested the 36mm Hyperion Aspheric in my 100mm f/6 refractor, an 8
inch f/5 Newtonian, and my Nexstar 9.25 inch f/10 SCT. All in all,
the eyepiece performs pretty well, providing reasonably sharp star
images across a fairly wide field of view. Most of the major
aberrations are well controlled, although they are not exactly
absent. Chief among these were mild outer field astigmatism and
slight pin-cushion distortion, although again, they were not
extremely detracting. Star images were pretty pin-point over much of
the field, making for very nice views of the Double Cluster region in
my 100mm f/6 refractor (17x, 4.2 degree true field of view). The
astigmatism tended to gradually build-up with increasing field radius
rather than suddenly appearing at some point and getting rapidly
worse as one looked closer to the field stop. The astigmatism was
somewhat less than I see using my 40mm Mk-70 Konig, visibly less than
in the 33mm Swan, and vastly lower than I see with my 30mm Widescan
III (even in the Schmidt). I noted little in the way of significant
lateral color, field curvature, or kidney-beaning. The field stop
was fairly sharp and the 18mm eye relief was particularly pleasing,
as for once, I could just see the entire field stop while using my
glasses. Indeed, the view of the moon using a low-magnification
Barlow was particularly nice, allowing me to view comfortably with my
glasses on (something few eyepieces ever provide me). There was some
very slight flaring of bright star images as you moved your eye
position, but again, it was a fairly minor effect. The coatings
appear to work quite well and the overall view was fairly color
neutral (neither warm nor cold). The view of M31 in all its glory
from my driveway using the Orion Skyglow was very nice, with the main
dust lane and the star cloud NGC 206 both being seen. Even M33
showed hints of its southern spiral arm with some mottling in its
outer haze. The eyepiece may not be quite on par with the more
expensive Panoptics or Naglers, but as a modest-cost “finder”
eyepiece, the 36mm Hyperion Aspheric looks to be a pretty good
choice. However, I found the included 1.25” screw-in adapter
to be a little bit of a gimmick, as it yielded a true field less than
72% the size of the 2” barrel field and which was noticeably
vignetted in its outer portions.
Summary
“grades”:
As I have often stated in the past, it can sometimes be difficult to
give a fully-accurate judgment of how good an eyepiece may be.
However, I can give the 36mm Hyperion the following grades:
Construction:
B+
(needs a tapered barrel rather than a safety groove).
Field
of view: B+
Astigmatism
Correction: B+
Lateral
Color Correction: A
Distortion
Correction: B+
Curvature
of Field Correction: A
Eye
Relief: A (allows
use with some glasses)
Cost/Benefit
Ratio: A
Overall
Performance: B+
Conclusion:
The Baader
Planetarium 36mm Hyperion-Aspheric
Eyepiece
is a good wide-field low to moderate power eyepiece with good eye
relief and a modest cost that should make it attractive to many in
the amateur community.
David
Knisely
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