Telescope Reviews: Widest FOV and asperic eyepieces with refractors?

Hi Zoeff:

I got your PM regarding the Aspheric 36 and will respond here. First though, did you see the review of this EP by David Knisely on the main Cloudy Nights page? I think his assessment is pretty accurate and agrees with what I've experienced.

As EPs get wider views and lower powers, they get harder to correct. So it takes some pretty good (and expensive!) glass to get a perfect or near perfect view when you're talking about 36mm and 70° plus AFOV. Point is, all EPs in this sub $200 range will experience distortions to one degree or another towards the edge.

Having said that, I compared several reasonably priced low power Wide view EPs and found that, for me, the Hyperion Aspheric fared the best. Specifically, I compared it agains the GO (Garrett Optical) 32mm, 72° AFOV Superwide. This is the exact same EP as the Q70, just in different trade dress.

Between these two I can wholeheartedly recommend the Hyperion Aspheric. The GO had significant field curvature over the outer 30% of the view. To me, if that much of the view is essentially unusable, you might as well be buying a narrower view EP. The Hyperion had some astigmatism but only at the outer 10% to 15% of the view. Plus the overall sharpness and contrast was noticeably better than the GO.

I also compared it to the Meade series 5000 34mm. The differences between the two were small, and it kinda depends on what particular distortion you like or dislike. The Meade did not have the astigmatism, but instead had very noticeable pincushion distortion. Scanning around the sky provided a fishbowl effect that I didn't like. For stationary views, it was maybe a slight bit better than the Hyperion, but was also MUCH larger and heavier. I ended up getting the Hyperion because having a lightweight EP that fits well in my EP case and doesn't throw my scope out of balance is also important to me.

I think the "Aspheric" simply means that the design uses aspheric elements which allows it to perform similar to other EPs but with much less glass. I'm guessing, but I think that's how it could compare so well to the Meade and yet be so much lighter.

-Dan

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Scopes: Celestron NexStar 8SE, Orion EON 72mm ED/APO, Orion ShortTube 80
Mounts: NexStar Alt/Az GoTo, Orion Astroview (EQ3) w/single axis drive
Eyepieces: Baader Hyperion 36mm (Aspheric), 21mm 13mm, 8mm, 5mm;
Other: 2x & 3x Barlow, 0.63x Focal Reducer, Dew-not strips, DewBuster controller, SQM Meter