Astronomik CLS Clip-Filter EOS APS-C (Astronomik, SKU: 10201082) is a filter that reduces the effects of light pollution in deep-sky astrophotography. It suppresses characteristic sodium and mercury lamp lines while transmitting broad regions of visible light and important nebular emission lines.
Its wider passbands than a UHC filter preserve more starlight. CLS can shift colour balance, so imaging data require appropriate calibration. The filter does not block infrared: a camera without its own IR cut-off needs additional filtration or the CLS-CCD version.
The Clip mount places the filter inside a compatible camera body, in front of the sensor. This allows the same filter to be used with different compatible lenses or a telescope and reduces dust settling on the sensor. The correct version must be selected for both the camera model and the lens.
Original Canon EF-S lenses are incompatible with the EOS APS-C filter installed. The filter works with suitable EF lenses and T2/M42 adapters. It can also be fitted inside the original Canon EF–EOS M adapter for EOS M cameras; this is different from direct EOS M filter mounting.
• broad passbands transmitting the H-beta, OIII and H-alpha lines
• suppression of sodium and mercury lamp lines
• less stellar dimming than UHC filters
• mounting inside a compatible camera, in front of the sensor
• durable coatings resistant to scratching and moisture
• filter: Astronomik CLS Clip-Filter EOS APS-C
• protective filter box
• manufacturer: Astronomik
• manufacturer product code: 10201082
• transmission bands: 450–540 nm and above 650 nm
• transmission: 92% at 486 nm, 496 nm and 501 nm; 97% at 656 nm
• infrared blocking: none
• mount: Clip-Filter EOS APS-C
• compatible APS-C DSLR bodies: Canon EOS 7D, 7D Mark II, 20D, 20Da, 30D, 40D, 50D, 60D, 60Da, 70D, 77D, 80D, 90D, 100D, 200D, 250D, 300D, 350D, 400D, 450D, 500D, 550D, 600D, 650D, 700D, 750D, 760D, 800D, 850D, 1000D, 1100D, 1200D, 1300D, 1500D, 2000D, 3000D, 4000D
• incompatible: original Canon EF-S lenses; full-frame bodies and EOS-1D
• glass thickness: 1 mm
• material: finely polished optical glass
• optical quality: diffraction-limited
• coating resistance: to scratching, moisture and ageing
• parfocality: with standard Astronomik filters using 1 mm glass
CLS helps reduce sky background brightness while preserving a broad range of signal from the objects being imaged.
