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. "
|
x
|
Price
|
|
8"
|
64
|
$0.1465
|
$9.00
|
|
10"
|
100
|
$15.00
|
|
12"
|
144
|
$21.00
|
|
14"
|
196
|
$29.00
|
|
16"
|
256
|
$38.00
|
