Simply put, the aperture in a camera lens is the adjustable hole that allows light through the lens and into the camera. Some lenses have fixed aperture sizes, but most have variable ones. When you see an Aperture Priority mode available on a camera, it means that as the photographer, you’re able to change the size of the hole that’s letting the light through to your camera’s sensor.
When you shrink your aperture (higher F number), you’re closing down the hole. There are two effects of doing this. First is that you’ll let less light through to the sensor and second, you’ll increase the depth of the depth of field in the photo. Conversely, if you enlarge the aperture in your camera’s lens (lower F number), you’re opening up the hole. The results from this will be more light being allowed to come through the lens as well as a shallowing of the depth of field.
Understanding aperture in a lens is actually quite simple. Things get more complicated when you begin considering how aperture can effect a photograph. Depending on the distance you keep your camera from your subject can have an effect on the resulting depth of field in a photo. Your aperture size plays a part in this. Also, aperture plays a huge part in the exposure of your photograph. A small aperture allows less light through and a large one allows lots of light. On dark days, you want more light, but on bright ones, you want less. When adjusting your lens’s aperture setting, you’ll need to weigh the benefit of increasing or removing light with how you want the depth of field to look in your photos.
If you’d like to read up more on aperture, please click through to the following posts I’ve previously written on the blog. They’re very informative, so enjoy.
The Real Reason to Use Aperture Priority Mode
Photography Basics: Shutter Speed, Aperture & ISO
F/8 is the Sweet Spot Aperture in Photography
What’s the Best Aperture Setting to Use For Landscape Photography?
How Do Camera Lens Aperture Sizes Compare to One Another?