London School of Photography Blog

Photography: Back to Basics (part 1) ISO

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For the uninitiated, auto mode on the camera would seem like a blessing. Point the damn thing where you want to take the photo and the camera does everything for you. Except it doesn’t. As expensive as it may be, as professional as it may be advertised, and despite leaps and jump in technological advances, modern digital cameras are still, well, stupid.  

In fact, the term “point and shoot” should really be banned, or renamed to “point, shoot and hope for the best,” because really that is what we are doing. You stick it on Auto mode, you take a shot of this wonderful moment and view the image only to discover the camera didn’t focus where you wanted it to. Or the photo is all shaky, or noisy (grainy), or entirely out of focus.  

Perhaps, in the not-so-distant future, cameras technology will evolve to the extent that its Artificial Intelligence knows what you are trying to do while you are shooting. It will recognise that you are trying to do a panning shot for instance and set itself up with the perfect shutter speed for you. It could perhaps understand that you want to completely blur the background or that you are shooting long exposures, and every decision it makes as regards to settings will be perfect.  

But until then, setting your camera in Auto mode in order to get a good photo is a like asking me to cook you a beef Wellington. What you will probably get is charred beef with a piece of bread stuck on top. When you set the camera mode on Auto, you lose any control you would have while shooting in manual mode. You cannot chance ISO, shutter speeds or apertures, because the camera wants to set those settings by itself. So the only way you can have complete control over your camera is to shoot in manual mode (M).  

So, what I will do in the next few blogs is revisit the foundations of photography with you, the holy trinity of photography that is the exposure triangle: ISO, shutter speed and aperture. These are tools with which you make your pictures, and mastering these tools through practice will help you create the images you want with the effects that you want them to have, like long exposures to capture the trail of the stars as the earth rotates, freezing drops of water or racing cars, and showing an entire field of sunflowers in focus. But, first things first. Today will concentrate on ISO.  

In the analogue days, before you took any photos you had to make sure you had film inside the camera, and the right film for that matter. I will never forget the face of a friend of mine who came back to the newspaper with a big smile on his face, thinking he had captured some great shots of the first lady in Cyprus fixing he president’s tie, only to realise to his horror that there was no film in the camera when he opened it. Rookie error? Absolutely, but these horror stories happened to us all.  

So film was where the image you took was recorded. You then processed the film and printed the photo and hoped for some good shots. And before you put the film in the camera you had to choose what ISO or film speed you would use, depending on the light conditions you were in. So the film sensitivity to light depended on what ISO number it had been assigned. The lower the number of the ISO (100 for example) the less sensitive the film would be to light, and the higher the number (like 1600) the more sensitive the film would be to light.  

So in bright days we used 100 ISO film because we already had a lot of light. In cloudy days we would use 400 ISO film and at night or poorly lit situations we would use higher numbers up to 6400 ISO. You may ask why do we need so much light to shoot? The reason for that is we want to avoid shaky photos, but I will get more to that when we talk about shutter speeds. 

In digital photography, film has been replaced by the sensor that digitally converts light into images that are then saved onto your memory card. The same principle when it comes to ISO applies, but the great thing about digital cameras is that you can change your ISO as often as you like with a range of options like ISO 50 to over 10000 these days. 

But using a higher ISO in digital photography comes at a cost and that cost is noise, or little coloured pixels that appear as red and green dots on your photo. So be careful when shooting in high ISOs in low light conditions. You can avoid noise by using lower ISO values and setting your camera on a tripod, or using a flash. Sometimes, however, we must sacrifice picture quality for picture content so we can shoot at these high ISOs in order to make sure we capture a fleeting moment.  

Just remember, in normal circumstances, use a less sensitive ISO for a bright sunny day, like 100, and increase as the light conditions vary during the day. Enjoy! 

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