Focusing Masks

Showing 1 to 12 of 65 total
Set Ascending Direction
Showing 1 to 12 of 65 total
Set Ascending Direction

Focusing masks are an inexpensive and easy to way to achieve perfect focus and are a must have accessory for astrophotographers. These simple yet effective masks attach to the primary end of your telescope and, with a specially designed grid, create a patternthat will help you adjust your focus. There are four types of focus mask patterns available on the market. Bahtinov masks are the most commonly found and widely used masks. The

Bahtinov masks are the most commonly found and widely used masks. With slits pointing in three different directions, the resulting crown pattern (three small dashes above and below the focus star) can tell you how much your focus is off and by what direction. 

Hartmann masks are cut either with circular or triangular holes.  This focus mask type is the only one that does not use diffraction and are best suited for gross focus adjustments as smaller discrepancies can be difficult to detect.  

Carey focus masks use slits in two angles, 12 degrees on the left and 10 degrees on the right.  The resulting pattern is a distinct X type pattern with two long dashes above and below the focus star. Very small adjustments are easily made with Carey masks. 

Perpendicular masks are the least common but create a unique cross pattern, with four sets of two dashes set at equal distances around the focus star.  Adjustments by eye with a perpendicular mask can be difficult but with analytical software, additional calculation and automated adjustment can create perfect focus.