Solar Filter

[OzStarGazer]

Hello,

I am thinking of buying a solar filter for my Skywatcher Heritage 130p. I have seen that sometimes they advertize them for newtonians or for refractors. So is there really a difference? And will a 114mm filter that is advertized as working for scopes "with an internal objective tube diameter of about 130mm" work with my Skywatcher Heritage? I think it should, but I just wanted to be sure because it doesn't say anything about the type of scope contrary to other ads I have seen.

Thanks!

[CJ]

I suspect the open sides of that scope make it unsuitable for solar viewing. I'm not sure of the mechanics of the angles/openings/mirror etc but I wouldn't try it without a shroud.

[OzStarGazer]

Thanks for the reply, Chris. You are right. That could be a problem. :( Apparently there is a thread about solar filters with collapsible telescopes on Cloudy Nights, but the website is down right now.

[Varangian]

Yes I have the same scope and it would be dangerous to attempt to view the sun using any type of solar filter.

[OzStarGazer]

Thanks, yes, I guess I should forget about it... :(

[rustigsmed]

hi,

i have a collapsable dob, that i used to photograph the transit of venus. i didn't use a light shroud.

http://www.flickr.com/photos/80336656@N07/7365371530/

the open sides probably degrade the image quality a tad but the main source of light (the sun) is facing directly at the scope.

I didn't use a light shroud over the truss and made with a sheet of RG film made my own filter with cardboard. This was a one off, event though and I had aligned the telescope before the sun came up so that it was always facing the sun directly (avoiding looking down at the primary).

I'd suggest without a very good light shroud using your telescope would be fairly dangerous. If you were to buy a filter (and light shroud) i would want to make sure it went around the external diameter of the solar filter went around the outside of the optical tube - not the inside :eyepop:!

Its probably all a bit risky although you may consider the projection method http://www.skyandtelescope.com/observing/objects/sun/Observing_the_Sun.html

cheers

rusty

[OzStarGazer]

I will read the article about projection, thank you. :)

[julianh72]

You could make your own full-aperture solar filter using a piece of cardboard mailing tube or PVC drain pipe as the shroud (big enough to fit over the open tube), and then either fit a ready-made solar filter over the front end, or else make your own filter using solar film.

You'd probably need to slot the tube to fit around the eyepiece / focuser, and you'd want to seal the slot with a flap or similar to be safe, but it shouldn't be rocket science (pun intended!) to come up with something that works.

However, if you're not confident with your ability to make a 100% light-sealed tube with no chance of leakage, I wouldn't try it - the consequences of stray sunlight hitting your eye are too dire.

If you are keen to do some casual solar observing, remember that high power / light-gathering aren't really necessary. (You're trying to restrict the amount of light collected, not increase it!) You could buy a cheap closed-tube scope (such as the Heritage 76, or a 50 mm / 60 mm "department store" refractor) and make a filter for it. See the attached photo - the blue and black object is a solar filter that I made from cardboard, masking tape and solar film - works a treat!

[OzStarGazer]

Thanks, Julian. Good idea. I wanted to buy a pair of binoculars for when I go on holiday, but I could also buy a really small scope under 2 kilos and use it on holiday but also at home for solar viewing with a filter. :)

[OzStarGazer]

Maybe I can buy a new eyepiece with the money I intended to invest in the solar filter. :)