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Finderscopes for solar projection?

[email protected]
 

Just wondering about whether anyone knows if a finderscope can be used
safely to project the image of the sun onto paper. Isn't a
finderscope like a tiny refractor? It should be able to project a
clear enough image of the sun to see sunspots.

What I don't know is if such a procedure would eventually damage a
finderscope or not. I guess it depends alot on the apeture of the
finderscope. One of my books "City Observing" ( Sky & Tel press )
says that inexpenive "refractors" 40mm to 60mm should present no
problem. Just be careful not to look through it though.

Later,
Rol
[email protected]
 

Some finderscopes would be damaged by solar projection.
Thats becase the solar image at prime focus will be
projected onto the reticle of the eyepice. If the reticle is a
plastic crosshair (common) rather than a scribed glass disk, then
it could well melt.

Check your finderscope by removing the eyepiece. Sometimes the
crosshair is removable. If you can take the crosshair out, then
a finder may well make an adquate solar projection scope.

-ad



--- In OAFs@y..., r.prevost@h... wrote:
Just wondering about whether anyone knows if a finderscope can be
used
safely to project the image of the sun onto paper. Isn't a
finderscope like a tiny refractor? It should be able to project a
clear enough image of the sun to see sunspots.

What I don't know is if such a procedure would eventually damage a
finderscope or not. I guess it depends alot on the apeture of the
finderscope. One of my books "City Observing" ( Sky & Tel press )
says that inexpenive "refractors" 40mm to 60mm should present no
problem. Just be careful not to look through it though.

Later,
Rol
Wagner,Rick [CIS-ADS]
 

My only concern is that the image of the sun is focused inside the scope on
the crosshairs. If they are delicate they may get cooked.
Rick

-----Original Message-----
From: r.prevost@... [mailto:r.prevost@...]
Sent: Wednesday, 28 March 2001 20:58
To: OAFs@...
Subject: [OAFs] Finderscopes for solar projection?


Just wondering about whether anyone knows if a finderscope can be used
safely to project the image of the sun onto paper. Isn't a
finderscope like a tiny refractor? It should be able to project a
clear enough image of the sun to see sunspots.

What I don't know is if such a procedure would eventually damage a
finderscope or not. I guess it depends alot on the apeture of the
finderscope. One of my books "City Observing" ( Sky & Tel press )
says that inexpenive "refractors" 40mm to 60mm should present no
problem. Just be careful not to look through it though.

Later,
Rol







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