Diy sun telescope

[AstroLuke]

Hello everyone!

Some friends and i want to make our own solar telescope. We want to be finished before 2014, we have gathered a budget of about 400 Euro. At the momeent the plans are to make a newtonian telescope, as there are many guides and books about this already!

None of us have ever tryed to build our own telescope so we have some questiens that we need answered.

First of all! We are building a telescope for looking at the sun, so the aperture should be quite small??

We have some formulas, but still need to find out how to calculate, how far an eyepice needs to be away from the mirror in order to be in focus?

We have only just begun planning, and i'm sure we will have more questions to ask (in this thread) in the coming months!

If you have any advice, guides or suggestions, please let us know!

Best Regards!

[Peter Drew]

I would recommend an aperture between 4.5" and 6" operating at around F8. The mirrors would not need aluminising but their rear surfaces should be ground and then blackened. The eyepiece position would approximately be the focal length less half the tube diameter and less the length of the focuser racked to half its travel. 

[Gina]

Be sure to use Baader sun blocking film, securely fastened in place or you could blind yourself! 

TAKE CARE!

[AstroLuke]

The eyepiece position would approximately be the focal length less half the tube diameter and less the length of the focuser racked to half its travel. 

Sorry im not sure if i understand this correct: Distance = f/l - Aperture/2 .... ???

Best Regards.

[Peter Drew]

If you don't mind imperial measurements let's consider a 6" F8. The information needed is to find the distance between the secondary and primary mirrors, this is where you would cut a hole for the focuser. The 6" F8 would have a focal length of 48", you have to measure back from the 48" position enough for the light from the primary mirror to be deflected far enough from the secondary to reach the eyepiece, this involves subtracting half the main tube diameter which would probably around 7" diameter for a 6" and also  subtracting the length of the focuser which would be arond 4". So, the hole in the tube would on this example would be 48"- (3.5" +4") giving 40.5".

I hope this is a little clearer. 

[tdmodels]

You might want to try using this Newtonian design software which is free on the web:   http://stellafane.org/tm/newt-web/newt-web.html