ERF Filter 200mm Artesky (SKU: ERF-200) all astro filters opinie

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Artesky ERF 200 mm (SKU: ERF-200 ) is a high-class Energy Rejection Filter designed for H-alpha solar observation systems. Mounted in front of the telescope objective, it reflects most of the heat and UV radiation, preventing overheating of internal optical elements and thermal turbulence in the tube.

The filter is made of transparent optical glass with very high uniformity, polished to the quality of the lens surface. The dielectric coating is applied on one side, which eliminates stress leading to deformation. It transmits a 60 nm band around the H-alpha wavelength (656.28 nm), effectively blocking light from the 200-1100 nm range and transmitting up to 95% of light in the target band.

Precision coatings are applied using advanced optical coating machines, which allows the full resolution of the optical system to be maintained. Reducing the amount of thermal energy reaching the interior of the telescope significantly improves the comfort of observations and safety for expensive H-alpha etalon filters.

Note: The ERF filter should only be used as a pre-filter for observing the Sun in the H-alpha band, in combination with an etalon filter (e.g. Daystar). It should be mounted in front of the telescope objective, with the coating surface facing the Sun (marked with an arrow on the edge). The ERF filter should not be used alone for visual observations - this may cause permanent eye damage. Frameless version - also available in a metal cell.

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 (without frame)

Technical parameters

• optical diameter: 200 mm
• central wavelength: 656.28 nm (H-alpha)
• Transmission bandwidth (FWHM): 60 nm
• H-alpha band transmission: 95%
• reflection range: 200–1100 nm
• cut-off depth: OD4
• surface quality: λ/4, finish 60-40
• edge chipping: <0.2 mm
• glass thickness: 12 mm
• manufacturer: Artesky – Italy