This filter is suitable for photography from areas with artificial light pollution using cameras that are also sensitive to infrared. It enhances the contrast of all deep sky objects. If your camera already has an IR filter, you can also use the slightly cheaper CLS filters (without the "CCD" suffix) from Astronomik.
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 attenuated. This filter is optimised to block as much stray light as possible and allow as much light from the objects to pass through as possible. The filter is ideal for use on telescopes of all apertures with aperture ratios from 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 lines of the airglow. All important emission lines of astronomical objects and the spectral range in which the eye has maximum sensitivity at night are transmitted. The integrated IR blocking layer allows use with digital cameras and webcams without their own IR filter.
Tips and further usage information
As an EOS clip filter, photography with DSLR cameras is possible even with extreme light pollution without damaging the colour balance. As a 1.25" and 2" version, it is also suitable for visual observation from light-polluted areas.
Alternatives
If an IR filter is already available for electronic photography, the more affordable CLS filter is a good option.
Suitability of the filter
- Visual observation (country): Good, with light pollution from mercury vapour lamps
- Visual observation (city): Neutral, a UHC-E or UHC filter is more suitable
- Conventional film: Very good, white balance is very good
- CCD astrophotography: Very good, optimal suppression of light pollution
- DSLR astrophotography (unmodified): Very good, colour shift but improved contrast
- DSLR astrophotography (astromodified): Very good, white balance is very good
- DSLR astrophotography (modified with MC clear glass): Very good, white balance is very good
- Webcam / video (Planets): Not suitable
- Webcam / video (deep sky): Very good if light pollution is a major problem
Technical data for the filter
- 95% transmission at 486 nm (H-beta)
- 95% transmission at 496 nm (OIII)
- 95% transmission at 501 nm (OIII)
- 97% transmission at 656 nm (H alpha)
- 1. Passband 450 nm to 520 nm
- 2. Passing range 640 nm to 690 nm
- Homofocal with all other Astronomik filters
- Not sensitive to moisture, non-ageing, scratch-resistant
- Fine-optical polished carrier material
- The filter is supplied in durable packaging
