The SMC 8-24mm Zoom Eyepiece fits all Pentax spotting scopes for terrestrial viewing, and can also be used with telescopes with 1.25 Inch focusers. It of/ers generous 18-22mm eye relief for comfortable viewing and an apparent angle of view as wide as 60. Built to Japanese Industrial Standards Class 4, it is weather resistant.Compatibility:Pentax PF-100ED, PF-80EDA, PF-80ED, PR-80EDA, PR-65EDA, PF-65ED(A)II spotting scopesOptical Performance:- Apparent angle of view 38-60- Long 18/22mm eye relief accommodates eyewear- Magnification: 26-78x with 100mm scope, 21-63x/20-60x/20-61x with 80mm scopes, 16-46x/16-48x with 65mm scopesConstruction Details:- USA Standard 1.25 Inch eyepiece threading diameter- Waterproof & fogproof (JIS Class 4-rated)- Multi-layer coated optics- High-refraction, low dispersion lanthanum glass- Accepts conventional 1.25 Inch diameter filters for astronomical and terrestrial applicationsZoom Eyepiece which is a high-performance and waterproof structure for daily life.Specifications:- Magnification:With PF-100ED: 26-78xWith PF-80EDA: 21-63xWith PF-80ED: 20-60xWith PR-80EDA: 20-61xWith PR-65EDA: 16-46xWith PF-65ED(A)II: 16-48x- Apparent Angle of View: 38-60- Field of View:With PF-100ED: 26-14 m at 1000 mWith PF-80EDA: 31-16.5 m at 1000 mWith PF-80ED: 33-17 m at 1000 mWith PR-80EDA: 33-18 m @ 1000 mWith PR-65EDA and PF-65ED(A)II: 40-21 m at 1000 m- Angle of View:With PF-100ED: 1.5-0.8With PF-80EDA: 1.8-0.95With PF-80ED: 1.9-1.0With PR-80EDA: 1.9-1.0With PR-65EDA: 2.4-1.3With PF-65ED(A)II: 2.4-1.25- Exit Pupil Diameter:With PF-100ED: 3.9-1.3 mmWith PF-80EDA: 3.8-1.3 mmWith PF-80ED: 4.0-1.3 mmWith PR-80EDA: 4.0-1.3 mmWith PR-65EDA: 4.1-1.4 mmWith PF-65ED(A)II: 4.0-1.4 mm- Eye Relief: 18-22 mm- Dimensions: 69 x 144 mm- Weight: 550g