William Optics Zenithstar 81 f/6,9 OTA FPL53 doublet APO, 2,5 R&P focuser in red (SKU: A-Z81RD) optical tubes OTA opinie

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William Optics Zenithstar 81 is one of the most recognizable structures on the market, intended for both astrophotography and visual observation.

The achievement of extremely sharp images with perfectly corrected chromatic aberration is due to the advanced and precisely made optics. The design of this refractor is a low-dispersion doublet with an air gap, in which the ED element is made of FPL-53 glass (synthetic fluorite). This material, produced by the Japanese company Ohara, has an extremely high Abbe number (94.94), and is additionally much more chemically stable and easier to process than crystalline fluorite. The surfaces of the lenses have been additionally covered with an SMC coating, the role of which is to improve the contrast by eliminating possible light reflections. The combination of all these features means that, despite its two-element structure, the telescope is often described as a full-fledged apochromat.

The tube of the telescope is mounted on precisely made clamps, equipped with a Vixen socket for the mounting of a finder or guide, as well as a Vixen / Arca-Swiss foot.

The most important features of the William Optics Zenithstar 81 telescope

• doublet with an air gap and a low-dispersion element made of Japanese FPL-53 glass (synthetic fluorite)
• solid rack & pinion extractor equipped with coarse and fine focus adjustment knobs
• optical tube clamps made in CNC technology
• mounting foot compatible with Vixen and Arca-Swiss sockets, allowing the tube to be mounted on a mount or photographic tripod

Technical specifications

• optical system of the telescope: ED doublet with air gap
• Objective diameter: 81 mm
• focal length: 559 mm
• lighted: f / 6.9
• maximum usable magnification: 162x
• ED lens material: FPL-53 glass (Ohara, Japan)
• optical system coating: SMC coating
• Compatible sensor sizes: APS-C, full frame
• fokuser: 2.5 "
• type of eyepiece: rack & pinion, dual speed
• thread for connecting the flattener / focal reducer: M63
• finder foot: Vixen
• mounting for mounting: Vixen / Arca-Swiss
• tube length (folded): 460 mm
• tube length (extended): 560 mm
• tube weight: 3.5 kg
• tube finish: white - red

Elements of the set

• William Optics Zenithstar 81 refractor (red)
• the pupa
• Bahtinov's mask with its mount
• a lens cap
• fixing clamps with the Vixen / Arca-Swiss foot

guarantee

24 months