6 Tips to Master Aperture Settings for Underwater Photography

By changing the aperture settings, you are changing how much light your digital camera lets in. Basically, the aperture of your lens is an opening that can be made smaller or larger. The larger the aperture, the more light your digital camera will let in. The size of an aperture is known as an f-stop. The smaller the aperture is, the higher the f-stop will be. The most common apertures are: F2.8, F4, F5.6, F8, F11, F16, F22 and F32.

A small f-stop would be 2.8. A large f-stop would be 22. When you make the aperture smaller, you are stopping down. By decreasing the f-stop by one stop, you are letting in 50% less light in comparison to the previous stop.

1. Ambient Light

One thing to keep in mind is that the aperture settings affect ambient light and strobe light. Every time you decrease the aperture, you are decreasing the amount of light that is let into your digital camera from all sources.

2. Depth of Field

The smaller the aperture is, the larger the depth of field will be. If you were to close the aperture by one stop (ie: going from F8 to F11), you will be increasing the depth of field of your digital camera by approximately 40%.

3. Sharpness

If you are using a DSLR digital camera, you need to keep an eye out for image sharpness in your shots. If you are using a small aperture, around F20 or larger, it is very possible that you will experience a lose of image sharpness when using 100% magnification.

4. Blur

Many people do not realize that aperture controls the blur, also known as bokeh, of the background. If you are using a large aperture, such as F2.8, there will be heavy blur in the background of your digital photographs. By using a small aperture, your photos should always have a background that is in focus.

5. Lens Performance

If your digital camera is equipped with a zoom lens or non-prime lens, the aperture settings will effect the performance of those lenses. These lenses will often perform at their best when the aperture is stopped down one or two stops. There is a rule known as "F8 and be there." This rule basically states that you should shoot at an aperture of F8 when you want the most sharpness and do not care about the depth of field or background.

6. Strobes

If you are using an external strobe light, which is highly recommended for underwater photography, you will need to keep the aperture settings in mind. If the aperture setting you are using is too small, it will prevent your strobe light from lighting the subject, if you are not close enough to the subject. This is due to strobe falloff. Many beginners will try to shoot an object that is approximately 2 feet away using an aperture of F22. Doing this will cause the subject to be underexposed, unless you have a very powerful strobe.

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