William Optics ZenithStar 81 Red AP 81/559 OTA apochromatic refractor

William Optics ZenithStar 81 Red AP 81/559 OTA apochromatic refractor
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Product no.: 62022
MPN: 62022
1.490,00 EUR
19 % VAT incl. excl. Shipping costs
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Test und Justage INED70 TS 70/420mm F7 ED Refraktor Carbon Tubus 2 Zoll Okularauszug

This telescope is checked, measured and adjusted if necessary before delivery. The focuser is set. Upon request, you will receive a meaningful quality certificate from your telescope (test report with star test, Ronchi, adjustment, with individual serial number) included! Please specify with order!
Examples of our test protocols: test recordings
How we adjust: About us

 William Optics ZenithStar 81 Red AP 81/559 OTA apochromatic refractor

The ZenithStar series from William Optics consists of compact but very high quality apochromats, which are ideal for use with a DSLR camera. This enables very good wide-angle images of large star fields. In combination with the optional flattener, these are right up to the edge, resulting in a corrected image field of 45 millimeters in diameter.

The light and compact ZenithStar apo and a DSLR ideally fit a photo mount, such as the Star Adventurer from Skywatcher or the Star Tracker from iOptron - a light and uncomplicated system for astrophotography.

The optics ZS81 is a two-lens doublet with an air gap and FPL53-ED glass, mounted in a precise CNC-milled lens cell. In combination with an optional 0.8 flattener, the opening ratio is f / 5.5 - ideal for astrophotography! The 2.5 "R&P focuser also does justice to the astrophotographic application. It has a high load capacity and a 1:10 reduction with an integrated mechanical thermometer. The scope of delivery also includes a specially developed Bahtinov mask with which the focus position can be checked with the camera connected.

Despite the relatively large lens diameter of 81 millimeters, the telescope is still quite compact and light. It is therefore suitable as hand luggage for air travel. The opening is already quite high for astrophotographic use, but the low weight and the rather short tube do not require a large mount.

The handle has a holder for the guide scope clamps or the finder scope with prism rail from William Optics.

The ZenithStar 81 is a dreamlike refractor with a very sharp and color-corrected image at a very fair price! The Apo can be optimally equipped for its own purpose using the extensive accessory system from William Optics.

Technical specifications:


type refractor
Type Apochromat Dublet
Opening (mm) 81
Focal length (mm) 559
Opening ratio (f /) 6.9
Resolving power (arc seconds) 1.70
Limit size (mag) 11.3
Light collecting capacity (-fold a 7mm pupil) 130
Max. Sensible enlargement (-fold) 162
Transport length (mm) 456
Tube weight (kg) 3.5

Type rack
Connection (eyepiece side) (inch) 2
Reduction 1:10 fine drive
Connection thread (camera side) M63
Free opening (mm) 64

type OTA
Mount type without mount
Included accessories

Handle yes
No carrying case
Other Bahtinov focus mask
Pipe clamps Yes
Prism rail Arca-Swiss & Vixen-Style
Taukappe yes
Series ZenithStar
Red color
application areas

Astrophotography yes (very good)
Moon & planets yes (very good)
Nature observation no
Nebulae & galaxies yes
Sun no (only with a suitable sun filter)
Recommended for ...

beginners no
advanced yes
Observatories no
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