8" f/6 Newtonian OTA fully optimized for planetary observations. Equipped with special features to bring out the highest potential of Newtonian system, such as very small central obstruction, thin vane spiders, 9-point flotation primary mirror cell, baffle rings inside the tube, long nose part working as a dewcap, extra large deep hollow on the other side of the focuser to eliminate the reflection lights, the ventilation holes in front of the primary mirror housing to suck in air from outside to relieve the tube current - all those features contribute to the extremely sharp, high-definition & high-contrast visual images of planets. Rigid GFRP (Glass-Fiber Reinforced Plastic) tube is lightweight enough to load onto mass-market small- to middle-class equatorial mounts. Comes with a low-profile 2" micro focuser. A large opening equipped on the side in front of the primary mirror for easy maintenance of the optical surface. An electric ventilator at the bottom of the primary mirror cell to quicken the thermal acclimation. Since this unique scope was on sale in 2002, it has attracted many Japanese serious planetary observers for years. Now it's your turn to enjoy crisp & clear planetary images through this custom-made special scope designed and manufactured with the utmost care by Kasai.
<Development Concept>
Primarily, Newtonian telescopes have very high potential for good visual images. However, not a few mass-market Newtonians are optimized for prime-focus photos, as with huge secondary mirrors, too thick spiders, etc., largely spoiling the original good image quality. Worrying this slanted situation, Kasai dared to make a special Newtonian embodying many factors to bring out the highest potential and to yield the very best images - it's NERO-200N.
<Optics & Cells>
Precision GSO primary mirror is installed. High homogeneity BK7 optical glass material. Each primary mirror is individually tested with ZYGO interferometer, assuring high quality as within 1/6-lambda on peak-to-valley wavefront, and 1/30-lambda RMS. The certificate with interferometric photo is provided. 93% enhanced coating brings clear images with little scattered light. The center mark is dotted to ease the collimation. The 9-point flotation primary mirror cell is supplied by Orion-Optics UK, preventing the deforming of the mirror surface and bringing out the best optical performance. By cutting off the excessive parts of the mirror fixing nails, image deterioration from uneven obstructions around the mirror is reduced. Spiders and secondary mirror cell are supplied by RP-Astro in Italy. 20.5% extra small central obstruction and 1mm thin 4-vane spiders contribute very high definition, exerting top performance in observing faint figures on planets.
<High-Contrast Tube Design>
The best characteristic of NERO-200N exists in the unique tube design. To realize the boldly deformed tube shape, flexibly-moldable and very sturdy GFRP (Glass-Fiber Reinforced Plastic) material is used. The top end of the tube is rolled inside like a baffle, and the nose part is long enough to work as a dewcap to eliminate the stray lights. The counter side of the focuser is shaped like a big & deep hollow to eliminate the reflection lights to the field of view dramatically. The tube diameter near the primary cell is about 10% larger than the front part, and a baffle ring is inserted in between. These features help to wall off the reflection stray lights from the primary mirror. Those thorough special features bring extremely high image contrast, as it shows very clear images without any color deterioration even in the daytime terrestrial observation with high power, and as it shows very dark background as the edge of the field can't be detected even when seeing a very bright planet. Multiple oval ventilation holes around the joint part of the tube and an electric ventilator on the back of the primary mirror help to vacuum the warm air current around the primary mirror, preventing the tube current from the beginning. A large opening (with a dustcover) is situated on the side in front of the primary mirror for easy access to the mirror surface, which can be cleaned easily and kept in good condition anytime.
A precision low-profile micro focuser with dual drawtubes is installed. In spite of the total height of the focuser is only 47mm, the total focus travel is such long as 70mm: 26mm travel by the outer tube + 44mm by the inner. The outer tube is operated with butter-smooth 1:10 dual-speed crayford focusing mechanism, and the inner tube is to be pushed-and-pulled smoothly. The 2" eyepiece adapter employs compression ring stopper system. A 1.5mm-height extra low-profile 1.25" eyepiece adapter (M48 filter threaded) is included. A finderscope bracket base is placed above the focuser, accepting many brands' brackets like Vixen, Synta, GSO, etc.
<Tube Rings & Plate>
Solid tube rings and Vixen-compatible long dovetailed plate is standard, fitting various mass-market mounts directly.
<General Aptitude>
NERO-200N is a "purified" Newtonian only for obtaining the very best visual images. Meeting all 3 important conditions (sharpness, contrast and definition), it's an ideal scope for lunar and planetary observations. The lightweight tube loadable onto a small mounting is also an advantage. Strongly recommended to those who longing for a non-compromised highest quality visual telescope.
Orion-Optics Primary Mirror Cell
20.5% small central obstruction
high-contrast tube design
Primary Mirror Cell
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A premium version with a gresearch-gradeh high-quality primary mirror of Orion-Optics UK is installed, assuring within 1/8-lambda on peak-to-valley wavefront, and 1/50-lambda RMS. The certificate with interferometric test report is provided. 97% reflectivity gHi-Luxh coating yields very clear and high-contrast images. Low-expansion gSupraxh (Schott, Germany) glass material. All the other mechanical features are the same.
Clear Aperture 200mm
Focal Length 1200mm
Focal Ratio F6
Central Obstruction 41mm
Obstruction Rate in Diameter 20.5%
Obstruction Rate in Area 4.2%
Max. Tube Diameter 230mm (Rear Part 255mm)
Tube Length 1285mm
Weight 6.8kg (8.3kg incl. Tube Rings & Plate)
Focsuing Mechanism 2" Micro Crayford Focuser w/Dual Drawtubes
Other Features *9-point Flotation Primary Cell
*Primary & Secondary Collimation Functions
*Multiple Oval Ventilation Holes
*Large Opening (with a dustcover) beside the Primary Mirror
*12 volt-operated Ventilating Fan for Primar Mirror
*Dovetail Base for finder Bracket
Standard Accessories Dustcover
Low-Profile 2"/1.25" Eyepiece Adapter (w/M48 Filter Threads)
Tube Rings & Vixen-Compatible 335mm Dovetail Plate
Interferometric Test Report of the Primay Mirror
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Glossy-black finished 8x50mm multi-coated achromat finderscope. 6-degree field of view with crosshair recile. Comes with a detacheable bracket.
8x50mm Finderscope w/Bracket
Kasai Trading Co., Ltd.
5-19-33, Kami-Meguro, Meguro-Ku, Tokyo 153-0051, JAPAN