CNC Laser Precision Aperture Masks
Sharpen image for lunar, planetary and double star observing.
Remove diffraction spikes caused by spider vanes.

Example aperture mask on 10" telescope.
Openings: 100% 3.7", 75% 2.77", 50% 1.85"
Two 4.33" interchangeable covers.

Sample Aperture Mask Diagram.pdf 

Reflective outside, flat black inside.
100% opening is sized to fit from secondary holder outer edge to the primary mirror edge.

Custom Sized Three Aperture Masks

"I was literally stunned at my first views of such clean crisp star images. Having observed double stars with my 10" f/5.7 Newtonian and its secondary spider creating distortions, the mask immediately showed why unobstructed views in refractors are so desirable. It was like putting on glasses for the first time, Alberio with small prefectly circular stars, clean airy disks, pure colors. Easily swapping mask covers, I found stopping down to 50% was best. Epsilon Lyrae's individual magnitude differences were obvious with clean separations and perfect individual airy disks." - Mark W.

When observing detailed objects such as double stars with a Newtonian, the secondary spider creates spikes deforming the image. An aperture masks eliminates those distortions. Varying size openings provide choices in brightness toning down and separating otherwise impossible double star splits. And a function of increasing the focal ratio is higher contrast: a 10" f/6 masked with a 3" opening becomes an unobstructed f/20 telescope; wonderful for brighter detail targets such as Jupiter, its moons, Saturn, our Moon, and of course bright tight double stars or tight pairs of wide magnitude deltas.

1/8 " thick flat black acrylic; rigid, lightweight and durable.
Aperture masks have three openings: 100%, 67%, 50%.
100% mask size calculated: edge of primary to edge of secondary.
See this sample detailed Aperture Mask Diagram.pdf.

Adheres securely to tube using Velcro dots.
Two opening covers are included.

Shipping up to 19.5" diameter: US/Canada $10/$15.
Shipping up to 23.5" diameter: US/Canada $15/$25.
Larger sizes or shipping to other destinations quoted upon request.

Price calculated by square area, $0.1465 per square inch
rounded to nearest whole dollar. Pricing examples:

Tube Outside Diameter
Sq. "

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