Camera Basics

Lens, aperture, F-stop and more explained for beginners
By Scott Gietler


An optical piece of glass that focuses the image as it enters your camera. On a compact camera, the lens is part of the camera, but on more advanced cameras, lenses can be removed or changed. Learn about lens basics.


Shutter speed

A camera has a "shutter" that opens and closes to allow light in, just like opening a blind in your bedroom will let in light. The longer the "shutter" is open, the more light comes in. The shutter speed is the length of time the shutter is open.


Aperture & F-stop

Aperture and F-stop are used interchangeably.

The aperture is adjustable opening in your camera lens that allows different amounts of light in depending on the size of the opening. 

F-stop is a relative measure of how much light is let in through the aperture. The F-stop is a number, such as 2.0, 2.8, 4.0, etc. The letter "F" always precedes the number. The larger the number, the less light is let in. F4 lets in half as much light as F2.8, and F5.6 lets in half as much light as F4. As you can see, the relationship is not linear. The following F-stops each let in half as much light as the previous one: 1.4 2.0 2.8 4 5.6 8 11 16 22 32. Most photography students commit this sequence to memory. Closing your aperture is called "stopping down" e.g. changing from F2.8 to F4. Opening your aperture is called "opening up", e.g. changing from F4 to F2.8. 


Depth of Field, DOF

DOF is the amount of your photo that is in focus. A photo with a small depth of field will have a blurry background.



ISO is how sensitive your camera sensor is to light. Most camera sensors have an optimal setting of ISO 100 or ISO 200. Raising the ISO, e.g. changing to ISO 800, makes the sensor more sensitive to light, and will have the effect of letting in more light without having to have a slower shutter or opening up the aperture. However, raising the ISO does not actually let in more light, and the cost is more noise in the photo and less dynamic range.



The amount of brightness in your photograph. It's a function of shutter speed, aperture (F-stop), ISO and flash power used when you take your photo. A "good" exposure means your photo has the brightness level that you intended.


Strobe, flash

An source of light artificially produced, in addition to light from the sun. A strobe or flash produces a burst of light at a very high speed.


Internal flash

Also called a "pop-up flash". It's the small flash that is part of your camera that can "pop up" when you need it. High-end dSLR cameras sometimes do not have an internal flash.


Ambient light

Light from the sun, also called natural light.



Here's the simplified version: If you have "TTL", that means your strobe/flash power is automatically adjusted for you, either by the camera, the strobe itself or an additional piece of electronics. If you don't have "TTL", that means you must set the power of the strobe/flash yourself.


White Balance

White balance is related to color temperature, and is how your camera interprets the colors in your photograph. Different white balance settings will result in a photo that looks more green, blue, red, yellow, etc.

Underwater Housing

A waterproof "case" or house that protects your camera and keeps it waterproof while allowing you to use the controls and take photos. Most cameras require an underwater housing to go underwater, although a few compact cameras are waterproof down to 10-30ft (3-9 meters).


Further Reading


Camera Basics
Scott Gietler
Lens, aperture, F-stop and more explained for beginners


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