The Letus35 Variable ND / Color Temp Filter Kit is a unique kit containing two separate filters, but able to provide three distinct effects: a standard circular polarizer, a variable neutral density filter, and a color temperature modification filter. The two included filters are essentially a deconstructed variable ND filter; one measures 138mm in diameter and the other is a rectangular 4 x 5.65", which are compatible with standard matte box configurations.
The 138mm circular filter is a standard circular polarizer on its own and features an indexed filter ring for noting points of rotation. This is especially helpful as it is an objective tool for repeating the same settings from shot to shot. When this filter is paired with the rectangular filter, it becomes a standard variable ND filter with values from 0.4 to 2.7 (1.3 to 9 stops). You are able to dial in different ND values depending on how much or how little you rotate the filter. For the color temp filter, you simply flip one of the individual filters over and control the color of the scene by rotating. This is ideal for modifying color balance between warm and cool casts and works more fluidly than working with the camera's white balance or modifying imagery in post-production.
These filters are both constructed from high grade German optical glass to ensure consistent image quality and light transmission.
- Circular Polarizer Filter
- A circular polarizer helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. The light from the sun naturally becomes partially polarized due to reflecting off electrons in air molecules, causing the light to scatter into what appears as haze. A polarizing filter arranges, and filters, this directionally polarized light perpendicularly to the reflected light, allowing for the absorption of much of this light. This results in a noticeable reduction of glare and reflections from non-metallic surfaces and an increase in the saturation of skies and foliage.
- Variable Neutral Density Filter
- This variable neutral density filter is capable providing an exposure reduction of about 1.3 to 9 stops. The 1.4 to 2.7 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than would normally be required. The degree of density is easily controlled by rotating the filter substrate, allowing you to visualize the additional exposure length required. By slowing your exposure time or increasing your aperture, you are able to both control depth of field and amount of movement conveyed more easily.
- Color Temperature Adjustment Filter
- A color temperature adjustment filter functions similarly to a variable ND filter, however instead of controlling the density you are modifying the color temperature by rotating one of the filter substrates. This allows you to dial in differing amounts of warmth or coolness depending on your shooting situation or for creative effects. Working with this filter is more intuitive and fluid in regard to a workflow as compared to modifying the white balance settings in your camera or spending excess time manipulating color during post-production.