Used Baader Solar Continuum Filter 1.25" 10nm

This is a used Baader solar continuum filter 10 nm in good condition. The optics are a little scratched and the body is unmarked which can be seen in the provided photos. This includes the original jewel case. 

Note: The 10 nm filter is an older version that has now been superseded by the 7.5 nm filter which is what is described below. 

• 7.5 nm Solar Continuum 2" Filter, CWL 540nm with 2" screw-in thread
• A must for owners of achromatic refractors. This narrowband-filter cuts the spectral range where lens optics draw sharpest and contrastiest. The Solar Continuum Filter brings power back to you.
• Enhances contrast and reduces the effect of atmospheric turbulence (in combination with white light solar filters)
• Enormous contrast gain in monochrome photography even on pure color systems
• Important note: The Solar Continuum Filter must be used for purely VISUAL solar observation ONLY with additional filtering (e.g. Baader Herschel prism or AstroSolar Safety Film) 

The Solar Continuum Filter is practically a narrow band photosphere filter for solar observation in white light. It provides the highest contrast in the photosphere of the sun. The filter works as a monochromator: suppressing the effects of the atmospheric turbulence and delivering images that are significantly sharper.

Lens systems - including those of apochromats, catadiopters or eyepieces - are traditionally optimized for the spectral range around 540nm, since this is where our eye has the highest sensitivity. This narrowband filter therefore blocks everthing with the exception of the spectral range in which a lens optic works most sharply and with the highest contrast. The effect is greatest on achromatic lens telescopes; but there is also an effect on apochromatic telescopes, catadioptric systems, and even pure mirror systems by reducing air turbulence.

As a monochromatic filter, it is ideal for use on monochromatic cameras and can even provide a tremendous gain on pure color systems.

With a colour camera, as with deep-sky narrow-band photography, it is less effective as only the green pixels are used. Thus, although you still benefit from the improved image sharpness of the telescope that is optimised for green wavelengths (and the reduction of the influences of air turbulence), with a colour camera you cannot fully exploit the better image quality compared to monochrome cameras, as you are effectively working with reduced camera resolution.

Compared to the previous model with a 10nm half-band-width, this filter has a half-band-width of only 7.5nm, which increases the contrast even more. It thus replaces both the previous Baader 10nm Solar Continuum filter and the stacked 1 ¼" filter #2458392. The single filter is so good that stacking is no longer necessary - the contrast gain of a single 7.5nm filter makes stacking unnecessary, and this performance is now also available in 2".

The Baader 7.5 nm Solar Continuum also offers all the advantages of the CMOS-optimized Baader filters:

• Increased contrast, matched for typical CMOS quantum efficiency and s/n ratio
• Reflex-Blocker™ coatings, for largest ever freedom from halos, even under most adverse conditions concerning aux-optics
• Identical filter thickness to existing standards, with utmost care for parfocality
• Blackened edges all around, with filter-lead-side-indicator in the form of a black frontside outer rim, to additionally eliminate any reflection due to light falling onto the edge of a filter
• Each filter coated individually, with sealed coating edge (NOT cut out of a larger plate with coatings left exposed)
• Life-Coat™: evermore hard coatings to enable a non-aging coating for life – even in a most adverse environment

Specifications:

• Manufacturer: Baader Planetarium
• Net Weight (kg): 0.067
• Transmission Range: 535 – 545 nm
• Filter Thickness (Without cell): 2 mm
• HBW (Halfbandwith): 7.5 nm
• CWL (Central Wavelength): 540 nm
• AR-Coating: Reflex-Blocker™ hard coated, planeoptically polished
• Filter Size: 2 inch
• Filter Usage: CMOS, Contrast Enhancement, Solar
• Filter Mounted: Mounted (LPFC 6mm)
• Type of Filter: Narrowband
• Single or Set: Single Filter
• Filter Shape: round

Manufacturer part number: 2961581 or FSOL-2N