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Kokusai Kohki Japanese 1.25" Orthoscopic Eyepiece - 25mm

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Brand Kokusai Kohki
Part Number -

Product Info

Manufacturer Description

Top Notch workmanship, design and optical performance Maximum sharpness, resolution, throughput and contrast at a very reasonable price

Kokusai Kohki's world famous lineup of orthoscopic eyepieces sport the highest quality Japanese workmanship, sharp "eagle-eye" views and excellent color correction. Their OR eyepieces will satisfy even the most demanding planetary observer, including those used to much more expensive and "flashy" name brand eyepieces, but at 1/4 ~1/10 the cost!

Kokusai Kohki's OR eyepieces are all lovingly handmade, one at a time by craftsmen at the Tokyo factory. In production now for over 40 years, their optical, mechanical and design quality is something you can be proud of for years to come. High magnification inclined apo-refractor, Maksutov, SCT and Mewlon users will be especially pleased with their planetary and double star viewing performance. The gorgeous barrel design includes snug filter threads and a tight, sharp field stop that precisely defines the field of view.

For maximum image definition, contrast and light transmission, the eye lens of each eyepiece is multicoated, and all other surfaces are magnesium flouride coated. Eye relief is typical for this ortho design and images merge well when used in a binocular viewer. Apparent field of view of all focal lengths varies between 41 and 47 degrees.

This level of quality comes at a very low price, meaning that getting even an entire set or doubling up for binoviewing is a more than reasonable proposition. Eyepieces weigh in at 65~95 grams for 1.25" and eye lens diameters for the shortest three focal lengths range from 3mm for the OR4, 4mm for OR 5 and 5mm for OR6.

Kokusai Kohki's 1.25" orthoscopic eyepieces are available in 4mm, 5mm, 6mm, 7mm, 9mm, 12.5mm, 18mm and 25mm focal lengths. Every OR eyepiece includes plastic caps on both ends.


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Apparent Field of View 47°
Barrel Size 1.25" (31.7mm)
Bolt Case Included Discontinued Item
Bolt Case Size Agena 37x60mm
Coatings Multi-Coated
Design Orthoscopic
End Caps 2
Eye Relief by Design 20mm
Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6)
Focal Length 25mm
Rubber Eye Guard No
Blackened Lens Edges Yes
Manufacturer Kokusai Kohki
Eyepiece Focal Length 20.1mm - 30mm
Eyepiece Field of View Up to 50 degrees
Eyepiece Series KK Orthoscopics
Barrel Type With safety undercut
Eyepiece Weight 3.53oz (100.07g)