Some photographers use orange or red filters to allow slight amounts of blue wavelengths to reach the film, and thus lower the contrast.

Smaller filters cause less blurring, and allow detection of small, sharp lines.

The filter had allowed the agent to pass.

E-mails can also be blocked based on language, however by default the filter allows all languages.

The broadest filter allows imaging from about 400 to 1050 nm.

Polarizing filters do not allow only light of one polarization to pass through.

For solar observations, filters allow direct observation of the sun.

Some filters allow the addition of extra 'modules' of foam.

The filters on the glasses allow only one image to enter each eye, and your brain does the rest.

Other filters allow parents to place some restrictions on what children can view on the Internet.