William Optics Bahtinov Focusing Mask for 105mm-148mm OD Dew Shields


Diffraction Spikes: Bahtinov focusing mask

Made for telescope dew shield diameters of 105 mm to 148 mm (4.13-inches to 5.826-inches).



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William Optics Bahtinov Focusing Mask for 105mm-148mm OD Dew Shields

This optical acrylic sheet offers 92% of light transmission that will give you the biggest and brightest diffraction spikes when focusing. This acrylic mask delivers 3 times brighter diffraction spikes than traditional metal masks.



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Robert P.
United States United States
First Use - Excellent Results!

Last night had the first chance to use this for focusing on a Tak FSQ106 with a Nikon camera. Using a bright star and the camera screen magnify, it was very easy to see the pattern. I had focused before by eye s best I could, but the Bahtinov mask showed I was a little off and it was easy to correct. The mask itself is nice with adjustable padded screws. The claim with this mask is that it produces a brighter pattern. I have nothing to compare it to but can say the pattern is very bright and clear. Recommended.