Bahtinov mask for tubus with outer diameter 63 to 139 mm | Astrozap

It’s difficult to see on the screen of your camera whether a star is really sharp. With this Bahtinov mask for a small telescope, you can see it: the mask creates three light spikes around a bright star.

Set the mask for the opening, point at a bright star and turn the focus ring until the middle spike is exactly between the other two. The mask fits a tube or dew cap with an outer diameter of 63 to 139 mm, which is especially noticeable with small refractors and Maksutovs.

Therefore, measure the outside of the front of your tube or dew cap, not the opening of the lens. Remove the mask before you start photographing. More tips for your first shots can be found here. our guide on photographing stars.

If you have a William Optics refractor of 102 or 103 mm, then there is a mask especially for those viewers. If your tube is thicker, then look at The mask for 139 to 216 mm.