Learning photography

Introduction
Basics
Aperture
Shutter speed
iso-sensitivity
exposure triangle
Prime lenses
Zoom lenses
Image Stabilisation IS
Flash Photography

Introduction

Most people are doing photography are perfectly happy having their camera on the heart-mode (full auto). However if invested the money in a DSLR camera, you probably are not one of those people. Now you don't have to immediately jump to the other extreme (full manual) since there are in-between options which give you control, but help out. Below are tips for learning photography:

Basics

There are three basic settings which control how much light falls on the sensor (=exposure):

  1. The aperture regulates the lens opening - the wider it opens, the more light can enter
  2. The shutter-speed regulates the exposure. The longer the 'eye' is open, the more light gets in.
  3. The ISO-sensitivity sets the camera's light sensitivity. the more sensitive it is, the less light you need

So let's just put it wide open and to very sensitive, that should work right? wrong.
Every setting has certain 'side-effects', so it boils down to making compromises. Depending on what we want, we put the priority on of the above, and have to give in a bit on one or both of the other values. To get a better understanding, let's take a look at the settings, what ranges they have and what effects we can control:

Name Values/Range Effect
F-stop (Aperture) 1.4, 2.8, 4.0, 5.6, 8.0, 11, 16, 22, 32 Influences depth-of-field (blur/out-of-focus)
Shutter-speed 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000 Influences motion freeze/blur
ISO-sensitivity 100, 200, 400, 800, 1600, 3200 high iso-speeds give more 'grainy' pictures


Aperture

With the Aperture we can limit the range in which the image is sharp (depth-of-field). The minimum and maximum aperture values you can use depend on your lens. Generally the higher the aperture the more expensive the lens will be.

Exposure triangle (ISO, shutter-speed, Aperture (F-stop)

Imagine a person standing in front of a house.
  • with a large F-value (e.g. 2.8) we will see the person sharp and the house unsharp
  • with a low F-value (e.g. 16) we will see sharp through the entire range

For portraits, photographers want to put the focus on a single person (shallow depth-of-field) - which means they prefer a large F-stop value. Your camera probably has a portrait-mode, in which it tries to do exactly this.

Shutter Speed

With shutter speed, we'll be able to get either a 'blurred' or a 'frozen' image.

Imagine a helicopter with a rotating blade:
  • with a fast shutter speed (e.g. 1/4000 second) it will appear to be standing completely still.
  • with a slow shutter speed (e.g. 1/2 second) the rotor will be blurred

Your camera probably has a sports mode, in which it tries to freeze the action using a fast shutter-time.

iso-sensitivity

In general, we want it to be as low as possible (100, 200, 400) since larger ISO-values cause pictures with noise. Unfortunately this cannot always be avoided.

The below overview gives you an impression of what ISO-value to set.
  • 100-400 = bright summer day, outside
  • 800-1600 = cloudy, afternoon
  • 1600+ = evening, inside

Exposure Triangle

By changing the above three values we can control the exposure, and thus how dark or bright an image will be. This can be represented in the exposure triangle:

Photography tutorial showing the exposure triangle (ISO, shutter-speed, Aperture (F-stop)

If the image is to dark we can do the following:
  • increase iso (more sensitive)
  • increase aperture (open further)
  • decrease shutter-speed (open longer)
or if it's too bright, we can do the opposite.

Prime lenses

Prime lenses have a fixed focal length.
The advantage is that they usually have really small F-stop values (smaller then 2.0) and are small and light. The disadvantage is that you probably need multiple for different focal lenghts (as such they can be inconvenient since you will have to swap lenses more often)

Zoom lenses

Zoom lenses have a variable focal lenght. Smaller numbers mean a bigger field-of-view angle (good for landscapes) while larger numbers mean a small field-of-view (good for getting far-away object closer). The cheaper zoom lenses have F-stop values with a different F-value for the minimum and maximum focal lenght The more expensive ones go to F/2.8 and can have a fixed value over the entire focal length.

Now there is one thing to keep in mind - the minimum and maximum focal lenghts are given for full-frame camera's (the really expensive professional ones). The (pro)sumer models usually have a so called 'crop-factor'. For example the canon 550D has a cropfactor of 1.6.

If you multiply the focal length with this value, you get the corrected value. So a 70-200mm lens would be a 112-320mm lens on a camera with an 1.6 cropfactor. Notice that this is very nice for the maximum value (better zoom', but inconvenient for the minimum value (not as wide as on a full-frame dslr)

The below diagram shows what happens if you zoom between minimum and maximum focal lenght. Imagine the light-blue figure being your wide viewing angle. When zooming it moves towards the darker figure - and as such your angle gets smaller while at the same time increasing your 'range'.

photography tutorials diagram showing wide and zoom factor


The light-blue figure shows the minimum focal length and gives a wide angle.
The dark-blue figure shows the maximum focal lenght and gives a small angle.
The dashed lines show the in-between focal lenghts.


Image Stabilisation IS


IS only helps countering your own motion - it essentially improves handheld images shot at slow shutter speeds. If you have a blurry image, and the foreground and background have the same level or blurr then your image was blurred due to camera-shake.
IS does little to help you capture motion (i.e. to freeze a moving object like wildlife, sports - without having motion blur). In this case a fast lens ( large aperture ) is the only way to freeze the speed, besides increasing the ISO sensitivity. Motion-blur causes only a (small) part of the image to be blurry (e.g. while making a picture of a landscape, someone walks sideways through the shot) By tracking the subject with your camera (i.e. keeping the car in the same spot, relative to the camera's viewpoint) you can keep the subject sharp while blurring the background.


Flash Photography


Remote triggering of Canon speedlite's with the Canon ST-E2.

In general. flash (especially on-camera flash) has a very limited range. People photographing at concerts with flash (with the artist 30+ meters away) are - besides creating a lightshow - mostly wasting battery life.
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