Eclipse Filter

Overview

The Eclipse Filter (also known as Solar Eclipse Filter or Solar-ND) is an optical attachment filter for lenses or matte boxes, specifically designed for direct recording of the sun and solar eclipses. It is not a color or diffusion filter, but an extremely dense neutral density (ND) filter that attenuates sunlight many times more strongly than conventional ND filters. Well-known examples include the Firecrest Solar Eclipse filters from Formatt-Hitech and the Solar-ND Filter from Tiffen.

An additionally integrated infrared blocking filter blocks radiation outside the visible spectrum, which the camera sensor would otherwise detect and which can lead to color and image errors. As a result, these filters deliver a largely color-neutral image despite their high density.

Technical Specifications

The filter strength is indicated by optical density. The following values are documented for the Firecrest Ultra series from Formatt-Hitech:

Further features:

• Integrated infrared blocking filter (IR-Cut) in addition to UV filtering
• High color neutrality due to multi-layer/rare earth coating (referred to as Firecrest technology by Formatt-Hitech)
• Available as a round screw-in filter (typical diameters from 37 mm to 105 mm) as well as a square filter (e.g., 100 x 100 mm) for filter holders/matte boxes
• Tiffen offers a comparable model with a density of 5.4 / 18 stops in several filter threads

Use on Set

The filter is used when filming or photographing directly towards the sun – for example, when documenting a solar eclipse or when shooting the solar disk. Only the high density allows for correct exposure with usable aperture and shutter speed without overloading or damaging the sensor.

Safety Warning

These filters are expressly intended for use on cameras only. They are not certified according to ISO 12312-2 and must under no circumstances be used for direct viewing of the sun with the naked eye. Certified solar eclipse glasses are required for visual observation.