Customer comments and photos.
Dobsonian Mounts

Which mount is best for you?

Manual or Digital setting circles.
1 mount for 2 telescopes? Yes!
Stands to raise height
Amateur Telescope Making
Altitude Bearings
Image Sharpening Masks
Primary:  Fix Turned Down Edge.  
Imaging: Remove mirror clip flares.
Aperture: Eliminate spider spikes. 
Optimized Mirror Cells
Clamshell & Rotating Rings
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 

Custom Sized Three Aperture Masks

When observing detailed objects such as double stars with a Newtonian, the secondary spider distorts the image creating spikes and unevenness. Aperture masks eliminate spider distortions. Varying size openings provide brightness choices for cleaning up and toning down the image. Aperture masks increase the effective focal ratio yielding higher contrast views: a masked 10" f/6 becomes an unobstructed 3" f/20 telescope; wonderful for brighter detail targets such as Jupiter and its moons, Saturn, Mars, our Moon, and of course tight double stars or pairs with wide magnitude deltas.

"My first views of clean crisp star images were outstanding. Using my 10" Newtonian on double stars, the secondary spider created distortions. Now with the mask, unobstructed views showed wy refractors can be so desirable. Alberio gave small prefectly circular clean airy disks with pure colors. Swapping the aperture cover, I found stopping down to 50% was best. Epsilon Lyrae's individual magnitude differences became obvious showing clean separations and perfect individual airy disks." - Mark W.

1/8 " thick flat black acrylic; rigid, lightweight and durable.
Aperture masks have three openings: 100%, 75%, 50%.
100% mask size calculated: edge of primary to edge of secondary.
See a sample mask diagramed at left.

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.

Order Mask:
For tube outside diameter up to:

We will send you an e-mail with a link to a dimension form. It will ask for tube ID and OD, primary and secondary mirror sizes, spider vane type (straight or curved) and number, and if the secondary holder stalk protudes beyond the tube.