What do all the Buttons on my Camera do??? Part 1 - What does the ISO Button do?

These days, so many people own a DSLR camera.  I get to attend a lot of weddings and the number of people with DSLR cameras grows all the time.  Often people will come up to me and are not sure what all the buttons and dials on their camera do.  Most people have their camera set to Automatic, which means that the camera does everything for you.  Automatic is a great setting if you need to take a shot that is happening at an instant and you do not have time to change your settings.

There are many features on cameras but there are three main settings that everyone should know about.  They are Aperture, Shutter Speed and ISO.  They determine exposure and form the foundation of every photograph we take.  


Aperture:  This is how large the hole/opening of the lens is.  The larger the hole, the more light can get inside and hit the sensor.

Shutter speed:  Determines how long the lens is open for.  The longer shutter speed, the longer the lens is open for and the more light can get inside.  

ISO:  This adjusts how sensitive the camera sensor is to light.  The more sensitive it is, the less light is needed in order to capture a decent exposure.

Today, we will look at ISO.  The ISO setting sounds complicated but it is probably the easiest setting to understand.  Quite simply, it makes your camera more or less sensitive to light.  Almost every camera, whether they are DSLRs or compact cameras, allow you to adjust the ISO.

Example:  You are at a party and the room is dark.  You click the shutter and see that the photo is dark or it’s bright but is blurry.

Why is it blurry?


This photo was shot at ISO 640 but is blurry.

The shutter had to stay open for longer so that more light could get in producing a well lit photo.  If you are holding the camera by hand and/or your subject is moving, then the image will be blurry.

Why is it dark?

Simple...... there wasn't enough light!  Depending on what setting your camera is on, the resulting photo may be sharp but be very dark.

One way around this is to use your flash but this will not usually be an option if your subject is far away.  The pop up flash on most cameras are poor at best but even so, you can only use them if your subject is close to you.

What should I do then?

If you can't use a flash, then you should increase your ISO setting.  Most cameras have the normal ISO set to 100 or 200.  Try increasing it to 400, 640, 800, 1000 etc.  This will make the sensor more sensitive to light and mean that the shutter is open for a shorter duration.  You will then get better brighter photos, which are not blurry.

This photo was shot at ISO 3200.  It is much sharper.


So why don’t I just whack up my ISO and leave it there?

Good question!  High ISO produces noise and a grainy picture, which most of us don't want.  Of course, if I had a choice between a blurry photo or one that was sharp but grainy, I would choose the latter every time!

So next time you are in a low light situation, check your ISO setting and increase it as necessary.

Take a look at Part 2 - What do all the Buttons on my Camera do??? Part 2 - A is for Apple.... Rubbish! It's for Aperture!