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mojolomjl

Long relief eyepice

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Could anyone advise me if a long relief eyepiece would enable me to view a bit further away from the lens as I find with my 10mm eyepiece my eye has to be very close to the lens and becomes uncomfortable after a few minutes.

Thanks in advance. btw my lenses are the standard ones supplied with the Skywatcher 130P.

Maurice.

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That's the idea - long eye relief EPs are generally a bit more comfy on the eye, and are often nicer if you wear specs (apparently!)

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Its one of the disadvantages of the Plossl design. The short focal length EPs have terrible eyerelief. A 4mm is even worse than your 10mm. Skywatcher do a range of long eye relief EPs which are reasonably prieced.

http://www.opticalvision.co.uk/astronomical_accessories/eyepieces/sky-watcher_long_eye_relief_ler_eyepieces

If you use a barlow lens you get higher magnification but the EP eye relief remains the same.

Mike

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I think the eye relief is actually increased in some cases. The panoptic 35mm is unusable in a regular barlow without the special pan-barlow adapter wotsit.

You could check out the TMB planetary range, they go from 3.2mm to 9mm I think, maybe there's a 2.5mm, can't remember. SCS Astro used to do them.

The snag with plossls is the eye relief is proportional to 70% of the focal length. So a 10mm gives around 7mm. Orthoscopics have very marginally more, 90% ish, but are still tight.

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You could check out the TMB planetary range, they go from 3.2mm to 9mm I think, maybe there's a 2.5mm, can't remember. SCS Astro used to do them.

Those are very good eyepieces and have comfortable eye relief - 16mm at all focal lengths. You can get them (well clones of them) on e.bay from a German company called Telescope Services and also a UK based online dealer, Bern at Modern Astronomy.

John

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The Baader Hyperion range are good for the price, good field of view too. I can't stand squinting through those little orthos.

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I got a second hand pristine vixen lanthaneum for £45 its the 9.7mm version and I have found it very useful.It has excellent eye reief.

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I've got both an 18mm ortho and a 9.5mm Super Apogee ortho and they have excellent eye relief. In fact, it was a pleasant change from Plossls when I got them.

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I have just managed to grab half an hour looking at the moon again before I began to freeze, and as I was putting the scope away I happened to notice that on the ep boxes it says "long relief eyepiece". How can I tell (being a complete novice) that they are actually long relief ? Any advice would be appreciated.

Regards,

Maurice.

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With a long eye relief eyepiece you should not have to press your eye right up close to the eye lens to see the full field of view (ie: the edges of the field stop). There is no specific definiton of what constitutes long eye relief as opposed to medium or short eye relief as far as I know.

Sometimes eyepieces can have eye relief that is too long and it's difficult to find the right position with your eye. People who wear glasses when viewing generally find eyepieces with more (longer) eye relief preferrable.

John

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