Hyperion zoom - by the numbers - NOT

I've had many kind words to say about the Hyperion Zoom and it is still my eyepiece of first choice. There's simply a lot I like about it. But I really do question the specifications they claim for it.

Don't get me wrong. I'm not a numbers person. What works for me, works for me - and the total experience of using this eyepiece works for me. Also, I am not an optical expert and I've performed no sophisticated tests. So with those caveats, I have to say the claim that the Hyperion 8-24mm zoom gives a 50-degree apparent field of view at the 24mm setting - something unusual for zooms - does not jibe with my experience.

Last night I was looking at the six-day old moon. It covered an angular diamater of 32 minutes acoording to Starry Nights software, which sounds about right. I thought it would fit in the Hyperion at the lowest power, but the field of view came up significantly short. That is, something like one tenth, or maybe one-eigth of the moon was missing.

Now the rough guide for finding the size of a true field of view is to divide the power into the apparent field of view. In the 8-inch LX90 the power should have been 83X. (That assumes the LX90 really is its advertised 2000mm focal length. ) Divide 83X into 50 degrees and you get a true field of view of 36 arc minutes. To get closer to the field of view I seemed to be capturing, the apparent field of view of this eyepiece at 24mm would be closer to the more typical 40mm of other, popular 8-24mm zooms.

So . . . I really hate wasting observing time on tests like this, but it's helpful to have some realistic idea of what your equipment is delivering in terms of the true field of view - helps you evaluate what you are seeing at any given moment - or what you can expect to see. So now, by the numbers, the Hyperion zoom has two strikes against it. The click stops don't seem to relate to the numbers claimed and the now the field of view seems to be smaller than claimed.

I can well imagine this scaring folks away from the eyepiece. But keep in mind my caluclations might be wrong. Or maybe I got a funny one. Maybe the new batch due out about now will be different. As I say, I'm not that worried about the specifics. I like the eyepiece. But when it comes to tehcnology, I don't like living in a fantasy world. I want accurate information about what I'm using. Knowing the true field of view is important to me. In fact, my basic goal is to use as few eyepices as possible and when I am using have complete command of the numbers - the power and the field of view. That's more important than any given eyepice delivering perfect images, because with that kind of information i feel I'm closer to making a real assessment of the reality in front of me.

I like to do things like cmpare the size of Saturn in a given eyepice with the size of a crater on the moon in the same eyepiece. I want to know the numbers, not because I really care that much with the apparent field of view is 40 or 45 degrees, but because if I know the numbers I can make the kind of evaluations of what I see that I find important. If you know the angular measure of something and you know it's distance from you, then you can calculate its size. Not that I do those kinds of calculations all the time. But I like them to be almost intuitive from constant reminder to myself of what I'm seeing.