APM Ultra-Flat Field 30mm 9-element 70° eyepiece--2"--a superb high-end eyepiece for a low price.

• 30mm focal length
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  70° field of view
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  22mm eye relief (18.5mm effective for glasses wearers)
  Foldable rubber eyecup
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  9 elements in 5 groups
• 
  Blackened lens edges
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  36.3mm field stop
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  Fully multi-coated
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  2" filter threads
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  54mm outside diameter
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  556g

The 2" UltraFlat Field Eyepiece features a high quality standard and a very compact design, which is designed to remove the field curvature at the edge, resulting in a flat, distortion-free image up to the edge of the visible field of view, even in very fast telescopes. The eyepiece has over - sized eyepiece lenses for the largest possible field of view and approximately a 20mm eyerelief - suitable for glasses wearers, the unfoldable eye-rubber allow a comfortable view. All lenses have a broad-band-multicoating (FMC) and blackened lens edges. The barrel is threaded for 2" filters.