ISO

ISO is used to control the camera sensor’s sensitivity to light.  The ISO value is likened to the ASA value used in film.  The higher the value the more sensitive it is to light.
Increasing the camera sensor’s sensitivity to light allows faster shutter speeds to be attained.  This is particularly useful when shooting indoors when light levels are low.
ISO is referenced in full stops.  With each ISO stop increase (higher ISO value) double the amount of light is recorded by the sensor.  With each ISO stop decrease (lower ISO value) half the amount of light is recorded by the sensor.

The table above shows ISO values in full exposure stop increments.

Be careful however, the more you raise the ISO of your camera, the more noise will appear in your photos.

Aperture

The aperture of the lens determines how wide the lens is open to let light in to expose the picture.
Aperture values are incremental and are always displayed in f-stops.

The table above shows aperture values in full exposure stop increments.  
When the aperture value is increased by 1 full stop (f4 – f5.6) the amount of light hitting the camera sensor is halved.  Similarly if the aperture value is decreased by one full stop (f2.8 – f4) the amount of light hitting the sensor is doubled.  Much like the iris of the human eye which becomes larger to let in more light the iris or aperture of the lens is made larger to let more light in, and smaller to let less light in.


The aperture is typically used to control the depth of field in an image. The larger the aperture (lower f-number e.g. f2.8) the less of the image there is in focus.  The smaller the f-number e.g f16, the more of the image there is in focus.
Larger apertures are typically used to isolate details in images and render the background out of focus.  Smaller apertures are typically used to keep everything in focus.  Landscape photos are typically taken at smaller apertures.


The wider the lens is open, the smaller the f number.  For example f1.4 is a very wide setting that will allow a lot of light through the lens onto the sensor, however a very small aperture for example f32 let's only a small amount of light onto the sensor.


The following diagram illustrates a lens aperture.

Shutter Speed

The shutter speed determines the length of time the shutter remains open to expose the picture.

Shutter speeds are incremental and are always displayed in fractions of a second.

The table above shows shutter speeds in full exposure stop increments.  

When the shutter speed is increased by 1 full stop (1/125 – 1/250) the amount of light hitting the camera sensor is halved.  Similarly if the shutter speed is decreased by one full stop (1/250 – 1/125) the amount of light hitting the sensor is doubled.  

Shutter speeds are typically used to control movement in an image.  For example, a slow shutter speed will show motion in a picture.  The image below was taken at 1/25s.  As you can see the waves are slightly blurred showing that they are moving.

The next example shows how a fast shutter speed freezes movement.

Shot at 1/1600s.  As you can see the dog’s movement is frozen and you can see every droplet of water as it splashes up.

Shooting Modes

On the top of your camera there should be a round dial with some pictures on it and the letters P, A, S, M.  If there isn't a dial these options may be in a menu somewhere, please check your manual for details.

The modes with pictures are automatic modes created by the camera for a specific purpose, which although can be fun to use, you have no control over how the camera works so we won't go into them here.

The four modes I recommend you use are as follows:

P - Programmed Automatic

I know what you're thinking, I said dump the auto, well this mode is a little different, this mode is automatic, there are several programmed shutter speed/aperture combinations that you can select between, so whilst you're learning I recommend this mode, that way you can cycle through the programs using the control wheel on the back/top of your camera to select the settings you wish.  Oh, and if the light gets low, the camera won't pop the flash up every two minutes!

A - Aperture Priority

This mode allows you to select the aperture you wish to shoot at, again using the control wheel, the camera will then select the appropriate shutter speed for you.

S - Shutter Priority

This mode allows you to select the shutter speed you wish to shoot at, again using the control wheel, the camera will then select the appropriate aperture for you. 

M - Manual

This mode allows you to select both the shutter speed and the aperture that you wish to use, the camera will not adjust either of these settings for you.

I only recommend this mode if you understand exposure.

Dump the Auto!

Shooting in Automatic mode won't help you learn about your camera's controls, in automatic mode, all the settings are controlled by the camera, the idea of this blog is to teach you a few controls and settings that will help you get a bit more from your camera, so with that in mind we will be using one of the four standard controls available on any digital SLR/four thirds type camera.

Exposure

A photograph is made when the sensor of a digital camera is 'exposed' to light.
Exposure is determined by three different factors:

• Shutter speed
• Aperture
• ISO

Shutter speed controls how long the camera allows light to hit the sensor. Longer shutter speeds allow more light to hit the sensor. Shorter shutter speeds let less light onto the sensor.


Aperture controls how wide the lens is open, the wider the aperture more light hits the sensor. Smaller apertures let leases light onto the sensor.


ISO controls how sensitive the sensor is to light.
These are the basics, I'll cover them in more detail in their own sections.

JPEG Vs RAW

This topic has been banded around the Internet so many times, but here's my take on it.

Shoot JPEG!

I shoot JPEG because I want to take pictures and learn from my mistakes. I shot RAW for a couple of years and ended up being lazy with my exposures and white balance, I used to just think 'I'll sort it later' but I never did.  Nowadays by shooting JPEG, if the exposure or white balance is wrong, I'll tweak my settings and re-take the shot, so I end up with the shot I want at the time.  JPEGs can still be edited if required but if you take the shot correctly in the first instance, you won't have much editing to do, that way you learn and move on to take more photos.

And I like the JPEGs my camera produces.

So set your camera to JPEG, Fine, Large.