Diffraction Spikes Bahtinov Focusing Mask for Telescopes Dew Shield Diameter From 105mm -148mm

This ingenious new tool from William Optics is a massive improvement over the decades-old Bahtinov mask used by many for manually focusing their telescopes. This new design generates high-contrast, clearly differentiated diffraction spikes on more stars in a photographic frame making it far easier to detect when critical focus has been reached. The angle and brightness of the diffraction spikes from this mask lets you see the the effect of very small adjustments of the fine focus knob on your scope. The diffracted star patterns are clear even at high zoom ratios, where old-style Bahtinov masks become unusable. I use this tool to check the accuracy of auto-focusing routines used by software like NINA and SGP, or as my primary focusing aid when I'm shooting with a DSLR. I can now get pin-sharp stars every time. This mask comes equipped with padded adjustable brass locator pins that make it easy to customize the fit of this mask for your scope, or to move it to other similarly-sized telescope.