About FOV

The other day I requested some information regarding ultrawide eps and the meaning of FOV, AFOV. Thanks for all responses. On Astromart under 'cool sites' is a webpage by David Green offering free software. A calculator is provided that will give all kinds of info including FOV and AFOV for any ep. You can run a comparison on several eps at once. It is brainless to use and only takes your scopes aperture, focal length, and ep aperture. He also provides downloads for observation notes and messier viewing. Wouldn't you know Astromart would carry such a great page. Thanks Mr. Green!!!!

Now I can say that a 9mm ep with a 67 degree AFOV will yield 0.5 degree view of the sky. The 82 degree nagler only offers 0.6, not much more, which I found interesting. However, I know of Nagler's reputation and the clarity is probably better.

Now my question is....has anyone tried and have an opinion about the new Orion Expanse eps. I did read the review on www.coudynight.com as recommended (sorry, I don't remember who recommended by thanks much).

I have them all, except under the Skywatcher brand name. They're all from the same place.

Generally very good eyepieces. They suffer from some serious ghosting/internal reflections, it seems to me, when viewing bright objects like Jupiter and Saturn, for example. I also think the eye relief is less than claimed. Other than that they're very well worth the money. Large and very usable field of view. Nice, sharp images over most of the field with just a little loss of focus at the edges. Good build quality too.

Keep in mind that the amount of sky you can see varies with the square of the FOV. So the Nagler in your example will show 44% more sky than the other.

That said, you probably won't see it all at once, because with Naglers the AFOV is so wide you have to move your gaze around to take it all in.

For me, a 68 degree AFOV is just about as much as I can take in comfortably.

Steve