Red filters are designed to make the photo more dramatic, whether that is in colour or black and white. At first glance a red filter coats the image red but when you transfer the file into photoshop you can adjust the colour filters, so the image isn't red anymore.
Underwater and red filters subtract other wavelengths rather than adding colour. This indicates that there is some light loss, therefore you may need to shoot at a higher ISO or use a wider aperture underwater to get a fast enough shutter speed. Except for minor enhancements, don't anticipate miracles; filters can only go so far.
The red lens filter is my favourite because of how it can automatically create darker and more dramatic lighting for the photo, it centres the subject.
Tips for Shooting Underwater
Shoot with the sun behind you to ensure that the subject is evenly lighted.
Adjust your ISO to achieve the desired aperture and shutter speed. When employing a magic filter, keep in mind that you'll lose a stop of light or more.
When it comes to the sun, you want plenty of light, so use your filter on bright days in calm, clear water.
For still subjects, use aperture priority mode; for moving subjects, use shutter priority mode. Test your camera to see if it requires the exposure compensation configured.
Instead of using your camera's flash or strobe, consider natural light. Turn off the flash on your camera.
All reds are gone deeper than 30 feet underwater, and no amount of filtering can bring them back.
Advice on Capturing Landscapes
The ability to analyse the quality of natural light in a landscape scene is one of the skills that distinguish the beginner from the professional.
Amateur photographers frequently struggle to determine what constitutes "excellent light." They also don't have a good idea of how to enhance it. To be honest, developing this skill requires a lot of practice but it's also where we'll start talking about filters.
Even the most beautiful scenery can be marred by poor lighting. However, superb lighting has the ability to make an otherwise uninteresting landscape stand out. The truth is that natural light isn't always ideal for landscape photography.
Red filters have a powerful effect and boost contrast dramatically. They can be used to create highly powerful and dramatic results, especially in landscape photography, where they can turn a blue sky virtually black and make clouds stand out even more. A red filter will aid to distinguish between blooms and foliage, which are often of the same hue.
A red filter will also penetrate haze and fog, allowing for better visibility. A red filter's extreme effect can make your image appear to have been shot via an infrared filter, making it a less expensive alternative to infrared photography. It will make a post box appear practically white, and a blue sky or green tree will appear almost black if blue and green are blocked.
The red filter was used for the first of the contrast filter images. It is rarely used for portrait photography. The red filter will turn a blue sky practically black and make clouds explode out of the frame in landscape photography, creating deep rich blacks and bright clouds.
Red filters have a big impact and improve contrast dramatically. They're typically seen to be too "aggressive" for portraiture, yet they can be used to create startling artistic effects. You will notice a significant boost in contrast, skin tone is lightened, and the shadows around the eyes increase.
A collection of coloured filters is a good addition to your camera gear if you're passionate about black and white photography and equally serious about black and white portrait work.