Re: suggestions for an easy solar telescope?

On 2006-01-19, Blaine Smart <bfore@xxxxxxxxxxx> wrote:
> I am a school teacher of 7th grade science students. This Spring, with my
> honors group, I'd like to have them build a simple solar telescope. The
> kind I have in mind is a simple type that I believe uses a single lens? and
> projects the sun's image onto a card placed behind the lens. Although the
> magnification isn't much, it still allows students to safely observe
> sunspots. Although I recall seeing the design somewhere on the web, I
> can't pinpoint anything specific. Can anyone suggest a link to the device
> I'm talking about?

I don't know a web site off-hand. You easily could build a simple
gadget using two lenses. You need a longer focus lens for the objective
and a shorter focus lens for the projection lens. You use the lenses
as a Keplerian telescope and space them to project the image onto a
white surface. The lenses would be mounted in a tube sticking out
of a box that has one side open so you could see the image. I'd look
for plano-convex lenses with focal lengths of about 100 mm and 25 mm.
Put them so the curved surfaces face each other. You would need to
play with the spacing between lenses and projection surface a little.
I did this years ago. It isn't hard to get a viewable image. Take
the usual precautions to avoid setting something on fire or letting
someone's little darling look directly through the thing at the Sun.

You can get lenses from Edmund Scientific
(http://www.scientificsonline.com) or American Science and Surplus
(//http://www.sciplus.com/). Edmund sells an expensive, ready-to-run
solar telescope called a Sunspotter for $350.

--
The night is just the shadow of the Earth.
.

Relevant Pages