A Beginner’s Guide to Understanding Camera Settings Control – Aperture, Shutter Speed, and ISO

Understanding how your camera operates is the first task after you’ve unboxed it. If you’re new to digital photography and this is your first camera, there is a lot for you to get up to speed. In this discussion, I will introduce you to the basics of camera controls, starting with shutter speed, aperture, and ISO.

The first thing that you should understand is the basics of camera operation, and by that, I mean the aperture control, shutter speed settings, and ISO changes. These three also happen to control the basics of every exposure. You will find the controls for aperture, shutter speed, and ISO at different positions on your camera. On some cameras, you’ve to use the main command dial.

On some cameras like my D850, you get two command dials, each controlling one aspect of shutter speed and aperture in the appropriate mode.

Remember that ordinarily, you can change only the shutter speed in shutter priority mode and the aperture in aperture priority mode. To change both, you’ve to switch to the complete manual mode. But there are ways around it. Exposure compensation can change the shutter speed in the aperture priority mode.

In the shutter priority mode, however, as in my D850, changing the shutter speed to too fast or too slow, depending on the available light, automatically triggers a change of the aperture value to compensate for either the lack of light or overabundance of light in the scene.

Let’s say it’s a bright day, and you try to dial in a slow shutter speed; the camera will detect that the exposure will be burned and automatically trigger a smaller aperture to compensate. The reverse happens if you try and use a very fast shutter speed (a fast shutter speed reduces the amount of light entering the camera).

The aperture that the camera will dial in will depend on the lens. If your lens opens up to f/1.8 and you keep increasing the shutter speed, the camera will dial in the widest aperture till it can. Afterward, if you continue to increase the shutter speed, the exposure meter will show that the exposure will be dark by skewing the reading towards the left (underexposed). The opposite happens when you slow down the shutter speed.

The ISO button is usually a dedicated button. Press the button and then turn the command dial to change ISO. You can choose to use a static ISO, in which case you will have to adjust the ISO whenever the need arises manually, or choose to use Auto ISO, where the camera dials in the right ISO number depending on the aperture and shutter speed you’ve dialed and the available light in the scene.