How Does A Red Filter Work

Shine the filtered beam on the white red blue and green papers and record the colors seen.

How does a red filter work. If too much infrared light gets through effects such as reduced contrast unnatural colour tone and other image-quality problems are introduced. They let the wavelengths of their own colours pass to the greatest extent approx. In the image on the right all colors of the visible range except red are absorbed blocked by a color filter thus letting only red light pass through.

The way I figure it out in my head is to divide 100 percent by the filter factor. A portion of the rays are reflected at the glass surface. It lightens trees a little and brings out contrasts inside orange sandstone rocks in the American Southwest.

After each test record the results. Owing to the dramatic effects given by a red filter it is. Then I count stops to compensate.

Sometimes that can be a very narrow band such as with the red and green gels or it could be a wider range of wavelengths magenta. When you look through a red filter everything looks red. Green trousers in White light only reflect green light.

These filters are handy due to the fact that red-free light is absorbed by the RPE creating increased contrast during your exam see pic on right. It also makes the sky look natural. For a start digital camera sensors can see infrared light so if you want to record a natural view of your subject you need an infrared filter to filter out infrared light.

While underwater filters are great for those who want a quick solution they are not ideal for all divers. Here are a few times when the red-free filter can help you during your exam. Low pass filters.