Transit of Venus (TV) Screen Workshop
Gene Zajac and Chuck Bueter
preparing for the transit of Venus on June 8, 2004, workshop participants
assembled a rear-screen projection device that slides into a 1.25-inch telescope
focuser. The Must See TV
(Transit of Venus) Screen, when properly assembled and used,
allows a group of people to view a magnified image of the sun simultaneously
without the risk of eye injury. After
a brief transit of Venus tutorial, we also presented alternative methods for
viewing the transit of Venus safely.
are the list of inexpensive materials, the suppliers we used, and simple
instructions to make the device. See
for supporting images.
use the TV Screen, simply slide the eyepiece, topped by the funnel and
screen, into the telescope focuser and aim the telescope at the sun.
Be sure to follow normal safety protocols when viewing the sun,
including (but not limited to) stopping down the telescope aperture if
necessary, removing the finderscope to prevent accidental exposure, and aligning
the telescope by indirect methods so as not to look directly at the sun.
When the sun is centered on the projection screen, adjust the focus until
you get a clear image of the sun.
can easily photograph the projected image.
If the image is too bright, block the aperture to step down the amount of
light entering the telescope. Change
eyepieces to increase magnification. Be
aware that if you remove the device when it is aimed at the sun, the sunlight
will come blasting out of the focuser.
Rear Screen Projection Material
Item number 41468
We used an 8 x 8 sheet, priced by the square foot, though a 7" x 7" sheet would suffice. The price is about nine cents per square inch.
cleaning the filter, use a soft cloth and water and gently wipe in one
Da-Lite Screen Company
3100 North Detroit Street
Post Office Box 137
Warsaw, IN 46581-0137
See http://www.da-lite.com for a
supplier near you.
1.25 Kellner 25 mm eyepiece
We purchased our eyepieces from a Canadian company that has educational pricing. They have a wide range of products for telescope building.
MPO Box 3164
Vancouver, B.C. V6B 3X6
FAX 1 (800) 648-4188
Funnel and Clamps
# 36318, 3 9/16
( $ 1.10) and # 36310,
We used a black oil funnel from Sears along with
two band clamps to secure the projection screen and the eyepiece.
Cut the funnel on a band saw below the bell of the funnel to allow the
eyepiece to fit securely. Then cut slots into the end with the band saw to allow
expansion for other eyepieces.
Stretch the projection screen material over the wide end of the funnel and secure it snugly with the large clamp. Be sure to eliminate wrinkles so that the surface is taut like a drum. The material will stretch easily.
the eyepiece into the narrow end of the funnel so the viewing end of the
eyepiece is within the funnel and secure the eyepiece with the smaller clamp.
The slits in the narrow end of the tube allow for a variety of different
diameters of eyepieces. Insert the eyepiece into a telescope and you are ready
to project an image of the sun.
you use a # 12 yellow filter, the projected image will appear more natural in
images of a larger, bucket-sized device, see www.transitofvenus.org/tvscreen.htm.
TV Screen is modified from Bruce Hegerberg s original Sun Gun at http://www.america.net/~boo/html/sun_gun.html.
Copyright ©2003-2008 Chuck Bueter. All rights reserved.