William Optics 75-110mm Bahtinov Mask

William Optics 75-110mm Bahtinov Mask: focusing without guesswork

The William Optics Bahtinov mask makes focusing on a star measurable. You place the mask in front of your telescope's aperture and point it at a bright star: the pattern will draw three spikes of light in your image. If the middle spike is exactly between the other two, the focus is perfect. No more guesswork, even with a camera.

This mask is cut from optical acrylic glass with 92% light transmission, and its design provides approximately three times as much diffraction as traditional metal masks: the diffraction spikes are brighter and can therefore be used even on fainter stars. This size fits small refractors such as the ZenithStar 61 and 73.

Features

• Fits pipe diameters of 75-110 mm thanks to adjustable mounting pins
• Optical acrylic glass with 92% light transmission
• About three times brighter diffraction pattern than metal masks
• Indispensable for sharp astrophotography, also visually usable

Compatibility

Measure the outer diameter of your tube or dew shield: it must be between 75-110 mm. For other sizes, there are the other versions in the series.

Specifications

You can find more accessories for this merk at the William Optics merk Page.