| This Astro-Tech 40mm Value Line Plössl is a good quality low power long eye relief eyepiece at a price that’s substantially lower than competitive Plössls. The eye relief is designed to be 31mm, and is claimed as such by similar eyepieces, and this is technically correct. However, because the eye lens (from where the eye relief is normally measured) is deeply recessed within the body of the eyepiece, the usable eye relief (the distance from where the image forms to the rolled-down eyecup, the closest point you can get your eye to the eye lens itself) measures 20mm. This is still long enough for essentially unvignetted eyeglass use.
The Astro-Tech 40mm Value Line Plössl has a good 40° apparent field of view, designed for the big picture of emission and reflection nebulas, for seeing entire open clusters like the Pleiades in one field, and for scanning nebular remnants like the Veil. Similar eyepieces may claim a wider field of view, some wider than is physically possible in a 1.25" eyepiece, but we choose to use a more realistic and accurate 40° value.
This Astro-Tech will work well with any telescope type (with the exception of fast focal ratio Dobsonian reflectors), at any focal ratio from f/6 and up. It works particularly well from dark sky sites where light pollution won’t reduce the contrast in its bright image. A knurled rubber ring on the body provides a secure grip when changing eyepieces in cold or damp weather.
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