* Astronomy

Baader Solar Continuum Filter 1.25 inch, 31.7mm

The Baader Solar Continuum filter is designed to enhance the visibility of solar granulation and sunspot details. By transmitting a specific spectral region around 540nm, free of emission and absorption lines, the Solar Continuum filter is able to boost contrast and reduce the effects of atmospheric turbulence. With the Solar Continuum filter in place, images snap to focus, and granulation becomes regularly visible. Details at the limit of visibility become easier to hold, and image motion reduced. 
The Solar Continuum filter works well in all types of telescopes, for both visual and imaging. Users of SCTs and achromatic refractors will find it particularly beneficial, as it completely excludes the red and blue wavelengths, and centers on the peak visual wavelengths where the telescope optics are sharpest and free from chromatic aberrations. For digital imaging, we also recommend the Continuum filter be combined with the UV-IR Cut filter (to completely cut the defocused far infrared wavelengths).

Important: The Solar Continuum Filter MUST only be used in conjunction with the recommended SOLAR FILTER for your telescope. Failure to do so will result in serious eye damage or blindness.

Solar filters comparison

Baader Planetarium Solar Continuum Filter - 1.25"

• This Baader Planetarium Solar Continuum Filter comes in a fully-threaded 1.25" round cell.
• Works in conjunction with a primary white light solar filter (or Herschel Wedge Prism) to show more granulation and sunspot detail!
• The Baader Planetarium Solar Continuum Filter boosts contrast, cuts down on atmospheric disturbances but transmits at 540nm.
• Good for both visual work as well as imaging, and even makes a good star test filter.
• The Baader Planetarium Solar Continuum Filter cannot be used alone when looking at the Sun, or eye damage and equipment damage will occur. Must be used in conjunction with primary solar filter.

Read more

A green filter (in combination with a suitable solar filter) will help define sunspots and surface granulations

Expand (271kb, 1024 x 768)

Expand (309kb, 1024 x 768)

Date: 24th March, 2012
Taken with a digital compact camera and Green filter.

Note: The image was taken through very thick mist with the Solar disk just visible to the naked eye.

A green light source typically has a spectral power distribution dominated by energy with a wavelength of roughly 487-570 nm.
Green is complementary to a purplish red or reddish purple colour, in both additive and subtractive mixtures, and in simultaneous contrast effects and afterimages.
The sensitivity of the dark-adapted human eye is greatest at about 507 nm, a bluish-green colour, while the light-adapted eye is most sensitive about 555 nm, a yellowish-green colour.
Read more

The Celtic languages had a term for "blue/green/grey", Proto-Celtic glasto-, which gave rise to Old Irish glas "green, grey" and to Welsh glas "blue".

LRGB Green Optical Filter