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Steve,
Your right, the eye relief is short and it gets shorter the shorter the focal length of the eyepiece. However you may find that as you become more experienced the short eye-relief is not such an issue, in some cases you learn to cope with it, some people never learn to cope with it. They don't make a 4mm HD ortho, they used to make a 4mm in the old volcano top style but chopped it due to its short eye-relief and subsequent user feedback. The eye-relief in an orthoscopic eyepiece is also fractionally better than an equivalent focal length plossl. ie The 5mm UO HD ortho has 4mm of eye-relief, a 5mm Plossl like the Celestron Ultima has about 3.7mm of eye-relief and the 5.5mm Meade Series 5000 Plossl also has about 4mm of eye-relief. Personally I have no problems using the 5mm UO HD orthoscopic but I was also raised on short eye-relief eyepieces.
CS-John B
Last edited by ausastronomer; 07-12-2005 at 04:36 PM.
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