Blue, green, yellow, frosted. For transmitted light
Microscope filters are used for visual observations and capture using a digital camera. They help improve the color balance of the image, increase contrast and brightness, and smooth out optical distortions. Depending on the color, the filter blocks a certain wavelength of light while allowing other wavelengths to pass through.
The blue filter cuts out the red spectrum, gives the image a cool tint, makes warm lighting from a halogen light source natural, and increases image clarity when using phase contrast. The green filter is used to smooth out spherical distortion from achromatic objectives and improve image clarity when using phase-contrast objectives. The yellow filter reduces color temperature, improves color rendering when using a halogen light source, and increases image clarity when studying the structure of metals. A matte filter is used to obtain diffused lighting. It is particularly useful when working on low magnification objectives.
All light filters are designed to work in transmitted light.