Retro fit solar filters

[Extreme Fencer]

Hi having thoughts about solar observing. I have a SW200p , I've been looking into the baader film.and watched S@N about solar etc

Also watched Pete Lawrence guide to making a filter on the S@N mag web site.

Found this ad for solar filters think there HAlpha they fit by means of an adapter plate.

http://www.solarscope.co.uk/sf-range.html

No price on the site expect them to be many of the Queens pounds opinions please. Thanks

[NGEddie]

That looked interesting until I clicked on the dealers page and looked at the prices. It would seem cheaper to buy an actual solar scope

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[Robny]

Holy moly did I read that right? Just over £3k for a filter. What can that filter do that a dedicated solar scope can't?

[Bizibilder]

With a 200P you should only really consider white light solar observing and the most appropriate filter for that would be one made from Baader film - either DIY or purchased complete. (The filters you have found are only for apartures up to 100mm and are really designed for refractors).

The normal £20 Baader film is only 200mm wide and therefore will not quite make a full aparture filter for your scope (you always have to "lose a bit round the edges" in order to secure it to the holder) but this is of little consequence. In solar work the image quality is governed by the atmosphere rather than the resolving power of your scope and there is little to be gained from using apartures over 100mm.

For your 200P I would suggest either fitting the filter behind the "little hole" in the plastic telescope cap (now you know what it is there for!!) or making a cardboard DIY filter holder with a 100mm hole "off axis" so the light will pass through the solar filter and between two of the legs holding the secondary mirror. Both will give you adequate viewing of the Sun with your normal eyepieces. If you have a camera you could try some solar imaging with the same set-up.

With this set-up you will see sunspots and faculae (whitish "streaks and blobs") as well as the granulation over the solar surface and you can follow things from day to day as they form and decay as well as following the rotation of the Sun.

Rather more specialised are the dedicated Ha (Hydrogen Alpha) Solar telescopes that start with the basic Coronado PST for a few hundred pounds. The price rises extremely rapidly for anything larger and quickly runs to several thousand pounds!!

[michael.h.f.wilkinson]

I use a white light solar filter on my C8 and a Herschel wedge on the 80mm. A dedicated solar scope (or PST mod) is often competitive with these front-mounted etalons. I am thinking about modding my LS35 inot a 70mm solar scope.

There is a reason these filters are so expensive: the optical surfaces of a Fabry-Perot etalon have tolerances more than ten times stricter than regular optics (I have seen 1/100, 1/200 lambda quoted). That is expensive. Many dedicated solar scopes have a smaller etalon about halfway down the optical path, which means it is much smaller than a front mounted etalon for the same effective aperture.

[markt]

The Solarscope etalons are expensive but worth it.

Go for Baader film on the SW200P as others have said...

[ollypenrice]

It is better value to go for a full Ha solarscope than a front filter because, as Michael says, they go in the back and can, therefore, be smaller. Also the near monochromatic light needs only a simple singlet objective lens, both cheaper and more effective than a doublet or triplet. You'll get good views in white light with your setup. Do remember not to leave your finderscope open to light, though, or it will relind you by burning a small hole in your head!

Olly

[allcart]

Do remember not to leave your finderscope open to light, though, or it will relind you by burning a small hole in your head!

Olly

Excellent advice Olly.