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Getting to grips with the terminology

So you’ve heard about apertures and flirted with f.stops, but what’s it all about?

There are three main components to achieving the correct exposure for your images: Aperture, Shutter Speed and ISO.  You will need to combine all three, and often make compromises to your settings to achieve the best results.  As ever, my doctrine is to have at least some idea of what you want to achieve before heading out with your camera.


The aperture governs the amount of light coming into the camera and is measured in f-stops/numbers.  Put simply, Aperture is the size of the opening in the lens when a picture is taken.

Shot at f-2.8 giving a small depth of field

Shot at f-18 giving a large depth of field

To confuse matters the smaller the f-number the bigger the hole.  For example an aperture of f-3.5 lets in more light than an aperture of f-16.  You can use different f-stops to achieve different degrees of focus.  This is known as Depth of field and determines how much of your photograph will be in focus.

Shutter Speed

This governs the length of time the shutter is open once you press the ‘shutter release button’, and therefore how long your image sensor has to capture the image it sees.  Shutter Speeds are fragments of time, measured in fractions of seconds.  You can use shutter speeds for effect as well as for making sure that your pictures are not blurry.

Shot at 1/30th second which blurs the subject

Shot at 1/250th second which freezes the subject

Here is an example of freezing/blurring action:

At slower shutter speeds, generally 1/60th second downward you will need to use a tripod to prevent camera shake.




The ISO measures light sensitivity: the quality of light hitting the sensor inside your camera.  The higher the number, the faster an image is formed and the more sensitive it is to light.

Different cameras perform better than others in low light conditions, but it’s generally best to keep your ISO low as higher ISOs result in larger pixel formation, often referred to as Grain or Noise.  This is where your images start looking a bit broken up or pixelated.

You may find yourself in situations like a Concert Hall or Church where you have no choice but to up the ISO. Bear in mind your aperture and shutter speed will be affected by this change.

Why not experiment with different settings to see how your camera reacts to changes in ISO?


Amanda Eatwell

07798 837969         www.ajephotography.com

[email protected]

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