Digital Photography Class: Exposure: ISO, Shutter Speed and Aperture

OK! So I assume that after you saw the previous post, you decided on which DSLR to buy. Once you have it, we should move on and the most important thing that you have to learn now is about exposure.

What is Exposure?

A photograph's exposure means how light or how dark an image will appear when it's been captured by your camera.This important process is determined by 3 camera settings: Aperture, Shutter Speed and ISO.

To make this easier to understand, I have here 2 photos that i took:

In this example, the photo is overexposed, that means i let to much light to go into my camera

In this one, the photo is underexposed, meaning that to little light went into the camera,

This example shows you the right exposure.What this means? The amount of light that went into the camera was good.

TIP:Always try to shoot your photos in a RAW format. This type of format will let you change many settings in the post-production process (Lightroom, Photoshop). Don't worry, I will tell you soon what that means.

Now that you understand the basics of exposure, it's time to go into details.

First of all, there are 3 things that you have to remember all the type:
ISO:Controls the sensitivity of your camera's sensor to a given amount of light.
Shutter Speed:Controls the duration of the exposure.
Aperture:Controls the area over which light can enter your camera.

Once you go into the Manual Mode of your camera, you will be able to play with these settings, depending on the situations, in order to get the right exposure.

ISO

The ISO determines how sensitive the camera is to incoming light. I correlates 1:1 with how much the exposure increases or decreases. Unlike the Shutter speed or the Aperture, a higher ISO will bring noise to the image, so try ti keep it low.

High ISO speed Low ISO speed

(High Image Noise) (Low Image Noise)

Common ISO speeds include 100, 200, 400 and 800 but they can go up 6400 or even higher with the top DSLRs. Using a DSLR, you can get acceptably low image noise in the range 100-800.

Shutter Speed

A camera's shutter speed determines when the camera sensor will be open or closed to incoming light from camera lens. I specifically refers to how long this light is permitted to enter the camera

Shutter speed=Exposure time (Same thing)

The shutter speed is probably the easiest from these 3 setting that i've been talking about. I correlates 1:1 with the amount of light entering the camera(e.g. When the exposure time doubles, the amount of light entering doubles). It also offers you the widest range of possibilities:

1-30+ seconds- Specialty at night and low light photos on a tripod
2-1/30 second- To add a silky look to a flowing water/a motion blur to the background of a subject
1/50-1/100 second- Typical hand-held photos
1/250-1/4000 second- To capture fast-moving subjects, sports, wildlife etc.

The slower the shutter speed, the more light goes in, the faster the shutter speed? You know the answer!

Here I present you 2 examples: 1 taken with a slow shutter speed and 1 with a fast one:

Here is the one with a faster shutter speed(1/200 sec.) It captured well the moment making everything clear.

Here is the one with a slow shutter speed(4 seconds).It didn't capture the car, only the light left by them.When shoot a slow shutter speed, ALWAYS! use a tripod!

Quick Tip:The flash always freezes the subject. For example you want to have your subject to look clear, no blurry while the background is taken with the slow shutter speed. You set the exposure time low (few seconds) and you also pup up the flash(make sure it is in rear sink). You hit the capture button and wait for the magic!

Aperture

A camera's aperture setting controls the area over which light can pass through the camera lens.It is measured in terms of F-stop. The bigger the f-stop the smaller the aperture is.The f-stop numbers differ from lens to lens, from camera to camera.A DSLR camera will have a f-stop up to f/32, starting from f/1.4 or f/1.8 etc. If you are shooting in low-light situations you would want to use a lens with a very small f-number (e.g. f/1.4) so you can get more light going in).

How it appears: A camera's aperture setting is what determines a photo's depth of field.The lower the f-stop number, the shallower depth of field o photo will have.

In this example, the photographer used a low f-number and the background is blurry giving a shallow depth of field.

This example shows you a large depth of field, meaning that the photographer used a big f-number.

Now that you know the main settings, you can start play with them.I will show you few examples of photographs took with a different combination of these settings.

The ISO is the ISO (Obviously)
F/ xy is the Aperture number
S.speed: zy is the shutter speed