This filter is suitable for photography from areas polluted with artificial light with cameras that are also sensitive to infrared rays. The contrast of all deep sky objects is increased.
The CLS CCD filter increases the contrast between astronomical objects and the sky background. Due to the wide transmission range, a large amount of light can pass through the filter, so stars are only slightly weakened. This filter is optimized to block as much stray light as possible and let through as much light as possible from the objects.
The filter is ideally suited for use on telescopes of all apertures with an aperture ratio of 1:2 to 1:15.
mode of action
The filter completely blocks the emission lines of low and high pressure lamps (mercury (Hg) and sodium (Na)) and the airglow lines. All important emission lines of astronomical objects as well as the spectral range in which the eye has the maximum sensitivity at night are allowed to pass. The integrated IR blocking layer allows use for digital cameras and webcams without their own IR filter.
Tips and other usage instructions
As a camera clip filter, photography with DSLR cameras is possible even with extreme light pollution without damaging the color balance.
Also suitable as a 1.25" and 2" variant for visual observation from light-polluted areas.
If there is already an IR blocking filter in the beam path in electronic photography, the more economical CLS filter can be used.
suitability of the filter
Visual Observation (Land): Good, subject to light pollution from mercury vapor lamps
Visual Observation (City): Neutral, a UHC-E or UHC filter is more appropriate
CCD astrophotography: Very good, optimal suppression of light pollution
DSLR astrophotography (unmodified): Good, color shifted but improved contrast
DSLR astrophotography (astro modified): Very good, the white balance is very good
DSLR astrophotography (converted with MC clear glass): Very good, the white balance is very good
Webcam / Video (Planets): Unsuitable
Webcam / Video (Deep Sky): Very good if light pollution is a big problem
Technical data for the filter
typically 95% transmission at 486nm (H-beta)
typically 95% transmission at 496nm (OIII)
typically 95% transmission at 501nm (OIII)
typically 97% transmission at 656nm (H alpha)
1. Passband 450nm to 520nm
2. Passband 640nm to 690nm
Homofocal with all other Astronomik filters except Astronomik XT filter versions
Filter thickness: 1mm
Resistant to moisture, non-aging, scratch-resistant