Reject Filter ERF 200mm with Metal Cell Artesky (SKU: ERF-200-MC330) all astro filters opinie

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Artesky ERF 200mm in metal frame (SKU: ERF-200-MC330 ) is a high-class Energy Rejection Filter designed for safe observation and photography of the Sun in the H-alpha band. With a diameter of 200mm and a solid aluminum frame, this filter is ideal for large-aperture telescopes, effectively reducing the amount of heat energy and UV radiation reaching the interior of the optical system. This reduces the risk of heating elements such as the H-alpha standard and eliminates convection phenomena inside the tube.

Using an ERF filter at the front of the telescope effectively reduces the temperature inside the optical system, keeping it close to the ambient temperature. Reducing heat prevents the formation of air turbulences that reduce image quality. Unlike absorbing filters, ERF reflects unwanted radiation bands, does not heat up excessively, and maintains full optical transparency.

Artesky ERF filters stand out from the competition with their top quality of workmanship. The applied dielectric coating provides a precise FWHM transmission range of 60 nm around the H-alpha line (656.28 nm), while effectively rejecting radiation from the 300-1100 nm range. The glass used as a substrate is highly homogeneous, finely polished to the quality of the lens surface, and the reflective coatings are applied on one side, while maintaining rigorous control of optical stresses. Thanks to this, the filter does not deform, which could deteriorate the telescope's resolution.

Artesky ERF filters are manufactured using the latest optical coating technologies. They guarantee the preservation of the telescope's full resolving power while significantly reducing the heat energy entering the interior of the system. This allows for better image contrast and minimizing the impact of thermal phenomena during observations and photography in the H-alpha band.

Why use an ERF filter?

• protects the H-alpha filter from overheating and damage
• eliminates air turbulence inside the tube, improving image sharpness
• reflects unwanted radiation bands (UV, IR, visible light except H-alpha) without absorbing heat
• ensures high light transmission in the H-alpha band – FWHM 60 nm
• made of high-quality optical glass with high uniformity and precisely controlled flatness
• dielectric coatings applied with the utmost care using advanced machines

Set components

• ERF 200 mm reflective filter in a metal frame

Technical parameters

• optical diameter: 200 mm
• central wavelength: 656.28 nm (H-alpha)
• Transmission bandwidth (FWHM): 60 nm
• reflection range: 300–1100 nm
• H-alpha band transmission: 95%
• material: optical glass, dielectric coating
• frame: aluminum, anodized
• manufacturer: Artesky – Italy

Important: The ERF filter should always be used in front of the telescope objective, as a pre-filter in H-alpha systems (e.g. with Daystar or similar filters). The filter's working surface must face the Sun - this direction is marked with an arrow on the mount. The ERF filter must not be used alone for visual observations - this may cause irreversible damage to the eyesight.