Beginners guide to Shutter Speed, Aperture and ISO

In this tutorial I will be explaining what aperture, shutter speed and ISO are and what they have in common, as well as the different roles they play in lighting for photographs. First off it’s important to understand that they all do the same thing, they all allow and restrict the amount of light getting in to the camera as well as having different benefits and disadvantages within that role.

Shutter speed is the length of time the curtain like shutter in front of the camera’s sensor is open. Shutter speed can vary, being open anywhere from 30 seconds to 1/8000th of a second. The longer the shutter is open the more light in held in the photograph, which at night can be great because there isnt much natural light. But during the day typically you need a faster shutter speed so not to overexpose have just a photograph of white blur. The second function of the Shutter speed is that as well as allowing in light it also helps determine whether the photograph will be blurry or still motion. For example the longer the shutter is open, the more movement it will capture. So if you’re photographing a moving object such as a runner, you will need a faster shutter speed to reduce the light going in to the sensor.


When shooting at a faster shutter speed it does reduce the light going in to the sensor, so it will possibly be to dark and need to be compensated by….

Aperture, this is the contracting ring in the lens itself which on the camera you can control. Aperture in measured in ‘F-stops’ and does change depending on the lens, but on the standard 18mm-55mm lens can go from F./4.5 to F./29. The smaller the number of the F-stop the bigger the hole open in the lens ring. The aperture also help restrict and allow light into the camera, which can help when shooting at high speeds in good light because you can open this further to brighten up the freeze motion picture with high shutter speed. The side effect of adjusting aperture is the adjustment of the ‘Depth of field’. This is where the smaller the aperture (higher F.) allows more of the picture being taken to be in focus. Here is an example:


If the Aperture is low for example F/16, less light will be allowed in because of the smaller hole in the lens ring, so more light is needed so you can see everything that is in focus in the photo you are taking, but fear not this is where we use….

ISO is the camera sensitivity to light when taking a photo. This is useful when shooting at low light because it utilises and enhances the light in the subject of the photo and brightens up high aperture photographs or low light photographs. ISO is measured in increments from 100 to 6400, this is a digital setting so is dependant on what the camera goes up to. The downside to ISO is the higher it goes the more prominent the grain or noise is in the photo, this means that when increasing the light sensitivity you are also taking clarity out of the image and unnaturally lightening it. This is okay until you get the top end of the scale it it can ruin a photo with excessive grain/noise.

As you can see all three of these directly affect each other and this aspect of photography. No matter where you are and what your subject is you will need to adapt and change these three settings as there isnt, unfortunately, one key set of settings that works everytime. So when taking your next photograph make sure you are balancing your Shutter speed with your aperture F-stop and making sure you have enough light in your photograph without too much grain.

If you would like to learn more, keep an eye out for our monthly photography studio workshops or if you would like to get in contact with us at Bstyle Photography Studio Coventry about our workshops please contact us on or call us on 02476 444438.

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