DSLR Cameras: Basics of DSLR Photography

Basics of DSLR Photography: ISO, Aperture and Shutter Speed.

The Exposure Triangle: ISO, Aperture, and Shutter Speed.

ISO: Camera Sensor's Light Sensitivity

ISO is the sensitivity of your camera's sensor to light. The higher the number, the more sensitive to light your camera will be.

That said, keep the ISO as low as possible for most situations.

ISO Range and Light Settings from 100-3200+

Think of ISO like "fake light". The more ISO we add, the more pixelated and grainy the image gets.

This odd-colored graininess is called Noise (see image below).

Noisy photograph of the sun behind clouds.

Rule of Thumb: High ISO for low light, Low ISO for bright light (H / L - L / H).

A good rule of thumb is to go low (around 100, or 200 in the shade) for high light (for example, outdoors) and to go mid-range (400-1600 at most) for low light (for example, indoors).

Too high ISO can result in grainy film and noise, but improperly set ISO can also result in an unclear image, either too bright or too dim. This can be dealt with by making use of the other two aspects: Aperture and Shutter Speed.

Aperture: Size of Lens Opening

Aperture is the size of your lens opening. The smaller the number, the bigger the hole, and the more light comes in.

The aperture is written in f/stops. The reason for this, is that f/stops measure the distance between the opening of the lens aperture, and the inside of the diameter of the lens. Hence, the smaller the number is, the closer the hole is to the outside of the lens.

Image showing different f/stops, measuring aperture

Aperture mainly controls the field of view, or depth of field.

You can use Aperture to properly focus on your subject, with a blurred background. Basically, it controls how much is in focus in front of and behind the spot you focus on.

Rule of Thumb: Portraits: f/2 or f/2.5, group shots to be at 3.5 to make sure everyone has a chance to be in focus, and a landscape with a tree in front and a mountain in the background should be somewhere between f/16 and f/22.

Overall: Aperture changes the amount of light that enters the lens, but also controls what’s in view and what’s in focus.

Shutter Speed: Speed at which the Shutter opens and closes

Shutter speed controls how quickly your shutter opens and closes to take photos, controlling both exposure and motion blur.

If it’s really bright, you’ll likely want to increase shutter speed in order to not have too much exposure. Likewise if you want to shoot a hummingbird that makes it look like it’s frozen in time, you’ll probably want to take the photo somewhere around 1/4000 of a second.

Image showing examples of a running fan taken at different shutter speeds.

Most cameras can go between 30 seconds and 1/8000 of a second for shutter speed. High exposure like 30 seconds creates the effect you see when someone takes a photo of a waterfall and it almost looks smooth like silk, or mist.

Cameras that can go up to 3 minutes give you gorgeous night photos of the moon, or the milky way. Sports photographers might set their shutter speed at a minimum of 1/800 of a second - the faster your subject is moving, the faster your shutter speed should be, to make it looks like your subject has frozen in time without any motion blur. But keep in mind, the faster your shutter speed, the less light your camera sensor is exposed to. That's why the 1/4000 speed image above is so dark - the sensor was only exposed to light for 1/4000 of a second.

Two Example Scenarios

What if your image is too dark?

First, slow the shutter speed until just before you start getting motion blur.
Second, lower the aperture, letting more light in. Make sure the subject stays in focus.
Lastly, raise the ISO if it's absolutely necessary. Do your best not to create film grain and color noise.
If you still can't get the photo light enough, it may be a situation where you need a different camera lens or accessories for the environment you're shooting in.

What if your image is too light?

First, lower your ISO. If you have plenty of light, you don't need to add "fake light". Lower it to achieve a clean image.
Second, raise your shutter speed. The less time your camera sensor is exposed to light, the darker your image will be.
Lastly, raise your aperture, if necessary. Depth of field looks great in photographs, so it's best to keep it low.
If these aren't enough, it's a good idea to make use of ND filters, which act like sunglasses for your camera.

Best Practices

Keep your ISO as low as possible. You can adjust the lightness of our photographs in other ways to adjust for lack of light, but when a photo is taken with too much exposure, it's impossible to fully correct when editing. Only rely on adjusting ISO higher if absolutely necessary, to avoid film grain and noise.

Try to keep your Shutter Speed high enough to avoid motion blur from hand shaking or subject motion.

Open your Aperture enough to let the proper amount of light in to counteract the proper ISO level.

Make use of camera modes. Automated functions make photography much easier, especially when practicing.

A Mode (or AV Mode) is Aperture Value mode. It means that you can set the Aperture to whatever you need it to be, snap the photo, and the camera automatically sets the Shutter Speed to what it's supposed to be.
S Mode (or TV Mode) is Time Value mode. Simply set the shutter speed to what you need, and the camera will adjust Aperture and other settings for you.