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Photography Tips - Digital Camera ISO

 7th Jun 2010

digital camera isoDigital Camera ISO settings are a tremendously handy tool which is often overlooked or misunderstood. Correct use of your ISO settings means cleaner, sharper and more evocative photos.

The ISO settings on your digital camera are a measure of sensitivity which back in the days of film were also called ASA.

Ah - remember the old days of Film? You had 100, 200, 400, 800 ... As the number got higher the film got what we call 'faster' and many people thought that a 'fast film' was for shooting a fast moving subject - which is partially correct.

What the 'fast' really meant was the speed the silver halide crystals in the film reacted to light and recorded an image. Well the ISO on your DSLR is much the same. As you increase the ISO number you're increasing the sensitivity of the camera sensor ­- great for shooting in low light.

‘But why don’t I just use my flash?’

Well ­- on camera flash is OK when there’s no other option, but it can kill the mood of a picture stone dead.

Look at these shots of Lorna - which were taken for our new photography training videos which we'll be launching in the Autumn.

We were sitting in a restaurant near a window and when I went to take a picture the camera’s own flash popped up because the light levels were a bit low.

digital camera flash 800 isoThe pic was taken at 200 ISO using flash. It's harsh, unflattering and the background has gone dark because the flash couldn’t reach right across the room to light it. There’s a nasty un-natural shadow cast by her right arm and the pic is totally devoid of life.

In the second shot I pushed the ISO pushed up to 800 which was just enough to give me a fast enough shutter speed not to get camera shake which would blur the picture.

Because the window to my right was doing all the lighting, the shot looks natural and has picked up the warm colour tones that were in the room.

Notice how the background isn't dark? The available light at the back of the restaurant isn't being left behind by the flash on the subject - so darker areas of the room have a chance to get some of their light onto the sensor and be recorded in the image.

And there's more!

As the ISO goes up and the sensor becomes more sensitive you can use smaller apertures if you want greater depth of field, or faster shutter speeds which will help reduce the risk of blurred pictures because of camera shake - not to mention be able to freeze motion more effectively.

Most digital camera ISO settings include an ‘Auto’ mode where the camera will choose the ISO for you, which could be handy - but there’s something to consider before you choose this option. The higher your ISO setting is -the grainier the picture will be.

This isn’t necessarily bad, it’s just something to consider.

If you wanted a fine detail shot like a flower or some other delicate subject which you intend to enlarge - then a high ISO setting might not be appropriate because you’ll lose some detail to graininess.

High ISO settings can also introduce what’s called ‘noise’ into a photo. Noise is made up of patches of dark coloured splotches in the shadow areas and is particularly noticeable on lower priced cameras.

digital camera ISOIf you've spent £1000 plus this shouldn’t be a problem and you'll be able to get great images all the way up to 2000 ISO - and in some cases beyond.

Another place higher ISOs can help is at a concert or any other dark indoor event where you're a distance from your subject.

We’ve all seen concerts on TV with flashes constantly going off in the crowd - ­but the sad fact is the pictures almost certainly won’t come out because the flash light isn't powerful enough to reach as far as the stage. All you’ll have is burnt out foreground and the action up front will be dark and underexposed.

If you switch off your flash and jack your ISO right up instead - chances are you’ll get a much better picture ­- even if it is a bit grainy.

Low ISOs give you ...

  • Finest quality
  • Best detail and brightest colour
  • Downside is that they make your shutter speed slower so in low light you might get blurry pictures through camera shake unless you use flash or a tripod.

High ISOs give you …

  • The ability to shoot in low light without flash
  • Faster shutter speeds to help stop camera shake
  • Downside is possible graininess and noise on cheaper cameras

If you’d like to know more about digital camera ISO or any other area of photography, please view our Photography Videos or try our beginners’ photography course. All are written in everyday language and are designed to help you take the pictures you’d hoped for in the shortest possible time.

You can buy all three for less than the cost of dinner and drinks at the pub. But hurry ­ the price will be going up soon.

Mike Browne - ISO settingsOr for some really great value photography tuition why not come and spend the day with me on a One-to-One course?

It's just you and me so there's no interruption from other class members and you can concentrate on whatever you need to. Call me now on 01590 670224

Until next time - happy shooting