This is an excellent very high power eyepiece (best used with the 7" Questars) for observing lunar and planetary detail, resolving globular clusters, picking up small planetary nebulas against a stellar background, etc . . .
This is an excellent very high power (217x and 325x in the 3.5" Questar), but quite dim, eyepiece for observing lunar and planetary detail, resolving globular clusters, picking up small planetary nebulas against a stellar background, etc.
The exit pupil is a very small 0.42mm at 217x, less than the 0.5mm generally considered to be the smallest useful on all but the brightest objects. The exit pupil is an even smaller 0.27mm when the Questar's Barlow is used to increase the power to 325x. This eyepiece is probably best used only in the 7" Questars.
It has very short eye relief that will significantly limit the field for eyeglass wearers. Those who must wear eyeglasses while observing due to severe astigmatism would probably be better off using the Questar's built-in Barlow and a longer focal length eyepiece with longer eye relief to reach this focal length, rather than buying this eyepiece for use on its own.
The eyepiece barrel is threaded to screw into the diopter adjustment tube on Questar telescopes, but will also fit into any 1.25" focuser or star diagonal. The 1.25" barrel is quite short, so be sure your non-Questar eyepiece holder thumbscrew barrel will fully contact the eyepiece to hold it in place before using this eyepiece in a non-Questar scope.
Shipping is free on this Questar item if it is purchased with a Questar scope that is being drop-shipped to you from the Questar factory. Standard freight charges ($9.95 minimum) and a 14-day or longer delivery time apply if this item is purchased by itself as a special order item. Additional Questar freight and a $15 Questar drop-ship charge will apply if faster delivery is required and it must be drop-shipped to you from Questar.
