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This eyepiece has a very large 6.9mm exit pupil with an f/4.5 scope, larger than some observers’ eyes can dilate. That can effectively waste some of the scope’s light gathering capacity, as some of the full light cone will fall on the observer’s iris, rather than entering his or her eye. Even so, some observers willingly trade a little light gathering for the immense field of view of this 82° apparent field eyepiece. This eyepiece very much provides a true “picture window of space” view.

You can use the calculator below to see just how wide the field will be with your particular telescope. For example, it will give you a 2.22° field at 37x with a 10" f/4.5 Dobsonian, more than enough to take in all of the Pleiades at one time. This gives you over eight minutes of uninterrupted observing with such a scope while an object drifts from one side of the eyepiece’s flat field to the other. That’s plenty of time for multiple observers to look at the same object, or for you to absorb as much detail as possible, before having to reposition the scope.

With a usable eye relief of 21mm, the 31mm Axiom LX will provide fully unvignetted views for most eyeglass wearers. However, since the 82° field is so wide that you can’t see the full field without having to move your head from side to side to take it all in anyway, vignetting in the conventional sense is not a problem in any case.

At 50 ounces, the 2" 32mm Ultima LX is a very substantial eyepiece. Be sure that your star diagonal is very firmly locked in place on your scope before inserting this eyepiece to avoid the chance of the diagonal swiveling unexpectedly and the eyepiece falling to the ground.

The retractable eyeguard raises by turning the broad rubber grip ring around the eyepiece barrel clockwise and lowers by turning the ring back counterclockwise. The eyeguard mechanism may be a little stiff in operation the first time you raise it.