February 18, 2012

DSLR Photography basics – Aperture, shutter speed and ISO


This photography post is exclusively for beginners who have just bought a brand new DSLR. While shooting with the automatic mode is fairly easy, the manual mode of your DSLR camera can be daunting — it’s a challenge just to figure out which buttons to push! Shooting with the manual mode of your DSLR unlocks the true potential of the camera with main adjustable parameters like aperture, shutter-speed and ISO. Therefore It’s necessary that you get yourself acquainted with these three basic foundations of DSLR photography.

After going through this post, you will be able to figure out - how to configure your DSLR in the manual mode while shooting in a variety of conditions. Now let’s take a look at each of them in detail with illustrative examples.


Foundation of DSLR photography – Aperture, shutter speed and ISO

1. Aperture

The aperture of your DSLR is the opening of the lens. Think of the way the human eye contracts and expands to let light in or keep light out. The lens of a camera works in a similar way. The wider the opening (or f-stop) is, the more light enters your camera. The narrower it is, the less light enters your camera. If your aperture set to a 3.5, for example, it means it’s open wide. If your aperture is a 28, it’s closed to a very small opening.

The aperture affects something called the depth of focus, or depth of field. This is basically how much of your photograph is in-focus, and how much of it is blurred. You’d use a large aperture (remember, that means a low number and open wide) for portrait shots, or any photograph in which you want the background to be blurry in order to draw attention to a focal point.

Examples where larger aperture value is preferred (subject in focus with a blurry background)

large aperture depth of field

large aperture depth of field

You’d use a smaller aperture for landscape shots, for example. That way, more of the photo is in focus, and you have less of a chance for a blurry photograph.

2. Shutter speed

This is basically what it sounds like — how fast your shutter snaps. When the shutter is open, it allows light inside your camera. The longer the shutter speed, the longer the camera is exposed to light, and the brighter your image will be. However, you have to maintain a delicate balance with shutter speed. As a general rule, when hand-holding a camera, it’s best not to go below 1/125th of a second. If you go longer than that, for example, 1/50th of a second, you have a much greater risk of your photos being blurry and shaky.

faster shutter speed for sports action

lower shutter speed motion blur

For action shots, like sports and fast-moving objects, you’ll want to have a fast shutter speed. Also, if the day is very bright, increase the shutter speed to bring the exposure back to normal. Slow shutter speeds are for darker settings — like city landscapes at night. However, you’ll need a tripod to avoid blur.

3. ISO

The ISO of your camera is basically how sensitive it is to light. So, the higher the ISO, the brighter your image. However, this comes at a price. As you increase the ISO number, the graininess of the photograph increases, and the quality decreases. There are several professional ways you can reduce noise in post-processing, but you’ll want to be careful to avoid going too high if you can.

For example, on a bright, sunny day, you’ll probably only need an ISO of about 200 - 300. At dusk or evening time, you might need an ISO of 800. And for night landscapes, you could need an ISO of 1600 or higher.

ISO camera basics

Remember that aperture, shutter speed, and ISO are all linked. If you change one setting, it’s likely that you’ll need to change the other settings to balance it out. For this very reason, these parameters are often linked to a term called – exposure triangle.


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Understanding the Exposure Triangle – the art of balancing aperture, shutter speed and ISO

For example, if you’re photographing a group of rowdy, fast-moving children, you may need to increase your shutter speed to prevent blur. When you do this, however, you’ll find that the photo becomes darker because the light isn’t entering the camera as long. So the two options are: open your aperture wider, or increase the ISO. Let’s say your aperture is already wide open — 3.5 or so. The only thing you can do is increase the ISO — let’s say to 500. Now you have a photograph that isn’t blurry, it’s bright, and it doesn’t have a lot of noise. This is quality photography, and it’s important to maintain the balance. All the aspects need to complement each other to create a beautiful work of art.

exposure triangle basics

It might seem difficult at first to keep track of all these different features of manual photography, but once you start practicing, you’ll realize that it’s actually fairly simple. You start to acquire a natural feel for it after a while. Soon you’ll be adjusting settings easily and snapping professional-looking shots. Keep working at it — practice makes perfect. Good luck!

Kailyn Nickel

About the Guest Author:
Kailyn Nickel writes at her personal photography blog - A New Rebel. She owns a Nikon D5000 and is well grounded in the basics of digital SLR photography. She hopes that you will find this photography guide pretty much interesting and intelligible.