SpectrumFilter SF -4, M55 Bluewater

The SF -4 spectral filter compensates for the colour shift of 8 metres of light path and reduces the brightness by four f-stops.

KELDAN Spectrum Filters explained from Wetpixel on Vimeo.

How it works

The Spectrum Filter SF -4 B is designed to compensate for the light absorption of blue water, providing an even, well-balanced light spectrum for your camera's sensor. This greatly improves the colour rendition of your images and matches colour values to daylight for excellent results with manual white balance.

The Spectral Filter is a powerful tool that can be used to adjust the colour of your images.

The SF -4 B spectral filter has a compensation depth of 8 metres. At this depth, the filter perfectly compensates for the light absorption of the water. The camera then sees a daylight spectrum, just as it does when shooting at the surface.

The filter is best suited for deep water in a depth range of 6 to 20 metres. The filter has a damping equivalent to a loss of 4 stops. Typically, low noise cameras that allow shooting at ISO 1600 or higher are required when using this filter.

IMPORTANT: If you have issues with low brightness levels, switch to a lighter filter such as the SF -2 (loss equals 2 stops). Using a lighter filter is always the better option than using no filter at all!

Overview:

• There are three different filters. A lighter version with 2 f-stops loss and two variants with a light loss of 4 f-stops.
• The -4 f-stop variant is available in two versions for blue and for green water.
• The filters are available for filter threads in sizes 55, 58, 62, 67, 72, 77 and 82mm.