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milkyjoe

Baader Solar Continuum Filter

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Hi,

I am thinking of buying one of these, but want to know if the £50 price tag is worth it? Do these filters actually change the colour of the sun or is it still white; how do they work?

Thanks

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I've not used one but from what I've read about them I'm clear that they must be used in conjunction with another solar filter such as a full aperture Baader AstroSolar filter.

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Yes they must only be used with a proper solar filter such as Baader solar film or a Hershel wedge. The filter just cuts out certain wavelengths of light at the eyepiece to improve detail and contrast.

John

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Hi John,

I realise you need a solar filter such as the baader solar film, I was just wondering what improvements, if any they make to one's viewing experience.

Richard.

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Hi John,

I realise you need a solar filter such as the baader solar film, I was just wondering what improvements, if any they make to one's viewing experience.

Richard.

The filter won't make a huge difference, but it just gets that little bit more detail and contrast, perhaps up to 10% better than you would be able to get otherwise.

John

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It's a narrow band GREEN filter (improving detail, while avoiding emission / absorption lines - In my understanding). ;)

Aside: I have trouble using one with my MAKs. "Somehow" the reflective coating on the front (Baader) solar filter, the silvering on the solar continuum filter (or the scope secondary?) conspire to set up huge on-axis ghosting? Perhaps it works OK with refractors. Perhaps it's just me! :o

Edited by Macavity

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I did some trials a couple of years ago, where the Baader Solar filter was used with all the different filters I had in my collection.

I tried the usual coloured filters you get, RBG, BVRI, narrowband ie OIII, Ha and some LPR filters as well as the Continuum filter.

IMHO the best results ie improved contrast and definition was found with the Continuum filter. A close second was a Light Green. None of the others did much good.

Yes, the image of the Sun will appear green. (I normally image with a mono DMK41 camera, so colour isn't an issue. Visually - you quickly get used to it)

HTH

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Macavity,

You may be getting a reflection from the FRONT of the secondary in the MAK...try a small piece of card either on the Baader film or on the front corrector to mask the reflective surface.

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Macavity,

You may be getting a reflection from the FRONT of the secondary in the MAK...try a small piece of card either on the Baader film or on the front corrector to mask the reflective surface.

Thanks Merlin - I suspect it's something like that, but the lateral thinking eluded me! <G> To avoid stressing the Baader film, I might try a dot of superglue on a small circle of (remainant!) D=5 RVO "Black Polymer" filter. Should be reasonably fail-safe too! ;) Edited by Macavity

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I did some trials a couple of years ago, where the Baader Solar filter was used with all the different filters I had in my collection.

I tried the usual coloured filters you get, RBG, BVRI, narrowband ie OIII, Ha and some LPR filters as well as the Continuum filter.

IMHO the best results ie improved contrast and definition was found with the Continuum filter. A close second was a Light Green. None of the others did much good.

Yes, the image of the Sun will appear green.

This does depend to a certain extent on (a) the magnification used, (;) your personal sensitivity to green light. I find that (a) the Baader Solar Continuum filter is very similar in effect to the ordinary (Wratten #58) green, just a bit better; (:o when used in conjuntion with the normal Baader solar film, both are a little too dense for comfort when used at high magnification. Try a deep yellow (Wratten #15) or even orange (Wratten #21). If your eyes (like mine) are relatively more sensitive to red and less to green than "average", you may find one of these works better.

I find Wratten #29 (deep red) is the best filter for "white light" imaging - the longer wavelength helps steady the seeing.

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Macavity,

I'd just start with a suitable sized disk held in place over the front of the secondary with blutack...if that works OK then look at other more "robust" solutions.

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