Astronomik Filters CLS CCD XT Clip Sony alpha 7 (85677)

Astronomik XT filters enable you to capture sharp, beautiful star images right into the corners of the frame, even with extremely wide-angle lenses.

Comparison with Other Filters

With other Astronomik filters, image quality in the corners can be limited at short focal lengths. Although these filters use a glass plate only one millimetre thick, this thickness can cause aberrations with certain wide-angle lenses, stretching stars into lines.

Unique Features of Astronomik XT Filters

Astronomik XT filters are built on an ultra-thin substrate, just 0.3 millimetres thick. This thinness minimizes “star streaks” in the corners. The substrate is finely polished, stress-free, and meets the highest standards required by astrophotographers around the world.

Despite the ultra-thin glass, Astronomik XT filters use the same advanced coating technology as all Astronomik filters. They are scratch-resistant, moisture-resistant, and non-ageing, maintaining 100% performance even after years of use.

Application and Advantages

This filter is well-suited for photography in areas affected by artificial light pollution, especially with cameras sensitive to infrared light. It enhances the contrast of all deep sky objects. If your camera already has an infrared filter, you can opt for the more affordable Astronomik CLS filters (without the "CCD" suffix).

The CLS CCD filter increases the contrast between astronomical objects and the sky background. Its wide transmission range allows a large amount of light through, so stars are only slightly dimmed. The filter is optimized to block as much stray light as possible while allowing maximum light from celestial objects. It is ideal for telescopes with apertures from f/2 to f/15.

How It Works

The filter blocks the emission lines from low- and high-pressure lamps (mercury and sodium) and airglow lines. All important emission lines from astronomical objects, as well as the spectral range where the human eye is most sensitive at night, are transmitted. An integrated IR blocking layer allows use with digital cameras and webcams that lack their own IR filter.

Usage Tips

As an EOS clip filter, you can use it for DSLR photography even in areas with severe light pollution, without ruining color balance. The 1.25" and 2" versions are also suitable for visual observation in light-polluted areas.

Alternative Options

If your electronic camera already has an IR filter, the standard CLS filter is a more affordable alternative.

Filter Suitability

• Visual observation (rural): Good, effective against mercury vapor lamp pollution

• Visual observation (urban): Neutral; UHC-E or UHC filters are recommended instead

• Conventional film: Very good, excellent white balance

• CCD astrophotography: Very good, optimal suppression of light pollution

• DSLR astrophotography (unmodified): Very good, with some color shift but higher contrast

• DSLR astrophotography (astro-modified): Very good, excellent white balance

• DSLR astrophotography (modified with MC clear glass): Very good, excellent white balance

• Webcam/video (planets): Not suitable

• Webcam/video (deep sky): Very good if light pollution is a significant problem

Technical Data

• 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)

• Passband: 450 nm to 520 nm

• Second passband: 640 nm to 690 nm

• Homofocal with all other Astronomik filters

• Resistant to moisture, non-ageing, scratch-resistant

• Finely polished optical substrate

• Supplied in durable packaging

Compatibility

Clip-on filters for Sony Alpha cameras can be used with models 7, 7r, and 7s.

Specifications

• Coating: Multiple coatings on the optical system

• Mount material: Aluminium

• Frame: Clip-filters

• Compatible with: Sony Alpha 7/9

• Filter thickness: 0.3 mm

• Type: Filters

• Build type: Broadband filters

• Series: XT

• Suitable for visual use: No

• Suitable for photography: Yes

• Anti light-pollution: Yes