I originally bought this eyepiece for my 130SLT. I love the views through it. Jupiter and Saturn look awesome. I recently bought a Celestron 12" Skywatcher Dobsonian and took the eyepiece out to look at M13 (Globular Cluster). It was breathtaking. It filled about 75% of my field of view. I bought it during OPT's hyperion sale earlier in the year. It was a great buy. I also own the 13mm, the 17mm and the 24mm. I use the 17mm & 13mm the most but this is a great eyepiece for high magnification. Plus, without the front lens group, it is a 21mm. I pop that off to scan for objects and then stick it back on to really zoom in.
Skip the 21mm its the underachiever. In a 10 f5 Newtonian I have the 36mm aspheric for 33x and a 7.5mm ep, the 24mm for 50x and a 5mm ep, 13mm for 95x and a 2.6mm ep and the 5mm for 240x and a 1.4mm ep. A nice combo of focal lengths for this scope, sure the edges suffer from slight coma in a short tube but over F6 its tack sharp especially in the longer focal lengths. Baaders coma corrector takes care of sub F6 tubes it if you're that fussy. Personally the wide and contrasty view through these ep's more than makes up for it and its really not that noticeable anyway. The overall quality is really quite high for the price and I would certainly recommend them as a very good upper-mid level eyepiece.
I've seen! Epsilon Lyrae -- The Double Double, with my SV80ED!!! in steady and dark sky an far from light pollution.
This eyepiece is well beyond what anyone would ever expect in the 100-200 dollar price range. Two years ago if i told you an eyepiece like this costs 119 you would think i'm insane. Buy this eyepiece, forget all the hype...just consider that this eyepiece is SOLD OUT at all of the best online vendors.
Excellent high power with medium/short scopes
I currently own the 5, 8, 13 and 21 mm models (and saving for the 36 mm. I use them in my 3 small (typical urban observer telescopes: Meade ETX 90 mm f/14, and Bushnell 127 mm f/12 Maksutovs, and 80 mm f/5 short-tube doublet refractor (***** A80-SSWT. The Hyperions look and feel big on these small scopes, but that's just about it, you can very easily get to using them without problems of handling or balancing. Optically, they do great, very honestly delivering the wide field and ample eye relief stated in the specs, and all with very good illumination and contrast. The only optical drawback is some evident, but reasonably expected and tolerable, edge distorsion when using the 13 and 21 mm in the f/5 short-tube. This is manifested by coma and spherical distortion in the outer surroundings of the viewfield, noticeable starting from around 2/3 out of the center while in the larger central region, the image is still quite excellent. I have done Moon, planets, star fields, and brighter fuzzies with the Hyperions all of it very satisfying observing. I can only imagine how they deliver in larger scopes or darker skies, but my humble experience with my urban lot of small scopes tells me these eyepieces should do very fine indeed. If buying a small basic set of Hyperions, I may suggest geting the 13, 8, and 21 or 24 mm (in that order as perhaps the most generally useful with any scope. As for myself, I tend to use 21 and 8 mm with the Maks, 13 and 5 mm in the f/5. The 5 mm gets too dim and washed out (over-magnified in the Maks while the 21 mm gives too much urban sky glow, besides edge distortion, in the short-tube.