The Kasai Astroplan eyepieces are excellent all-round eyepieces, especially for the discerning lunar or planetary observer. They combine the crisp definition of orthoscopic eyepieces with good field correction over a larger 50-deg apparent field of view. While these are good performers even at shorter focal ratios, they really come into their own with sharp, crisp, contrasty views in long focal ratio scopes.
Superior lens polishing with multi-coating on all internal air-glass surfaces (so these are FMC), a modern 5 element design, edge blackened optics, engraved lettering, end caps, and standard filter threaded barrels attest to the excellent craftsmanship of these Japanese eyepieces. The body of the eyepiece is made from strong, lightweight aluminum and features a knurled rubber ring, while the 1.25" barrel is made from chrome-plated brass.
These optical characteristics coupled with their small size make these Kasai AstroPlan eyepieces perfect for visual observation (especially in binoviewers) as well for afocal projection photography.
|Apparent Field of View||50°|
|Barrel Size||1.25" (31.7mm)|
|Bolt Case Included||Discontinued Item|
|Bolt Case Size||Agena 42x80mm|
|Height (without Eye Guard)||59.8mm|
|Eye Lens Diameter||19.5mm|
|Eye Relief by Design||17mm|
|Filter Threads||Standard 1.25" Filter Thread (M28.5 x 0.6)|
|Rubber Eye Guard||No|
|Blackened Lens Edges||Yes|
|Manufacturer||Kasai Trading Co.|
|Eyepiece Focal Length||15.1mm - 20mm|
|Eyepiece Field of View||Up to 50 degrees|
|Eyepiece Series||Kasai AstroPlan|
|Barrel Type||Smooth sided|
|Eyepiece Weight||4oz (113.40g)|