In the ‘olden days’ of film cameras the ISO rating referred to the speed of the film. Obviously digital cameras don’t have film so the ISO now refers to the sensitivity of the image sensor.

The ISO options on my camera range from 100 to 1600 - the lower the number the finer the grain in the photograph and the less sensitive the camera is to light.

If you’re taking pictures in an overly bright situation - such as on a ski slope or the beach on a sunny day you should choose a low ISO setting. If its a cloudy day or you are are shooting pictures indoors then increasing the ISO setting will increase the light sensitivity of the sensor. As the amount of light decreases the camera will slow down the shutter speed to try and let more light in - this can lead to motion blur. Increasing the ISO setting will counteract this and allow for a faster shutter speed.

High ISO settings are also good when you are trying to shoot fast moving people/objects as it allows the camera to gather more light and therefore increases the shutter speed.

The downside of high ISO settings is that the photograph becomes more grainy - this is why you shouldn’t leave your camera on a high ISO setting all of the time.

Every ISO setting has a purpose

Here’s a quick guide as to when you should use each ISO setting:

ISO 100: Perfect for bright sunny days, at the beach or on the snow. Produces clean images that are great for enlargements.

ISO 200: Use on overcast days - some grain may appear but shouldn’t be too noticeable.

ISO 400: Use for lower lighting conditions (indoors, night time) or when shooting faster moving subjects in lower lighting conditions. ISO 400 can make photos look very noisy in dark areas of the picture.

In practice

To test this out I placed Tigger in the bay window on a slightly cloudy day. I fixed the aperture and shutter speed and then took a photo at each of my ISO settings. As you can see below the lower the ISO setting the darker the photo. At 800 the photo looks too bright - and at 1600 its over exposed. You can see the grain starting to appear at ISO 400.

• Shutter speed: 1/200
• Aperture: F5.6

ISO 100

ISO 200

ISO 400

ISO 800

ISO 1600

If you enjoyed this article you may want to subscribe to my RSS feed to have future posts delivered directly to your feed reader. Thanks for stopping by.

Image by tanakawho via Flickr

Exposure seems to be the best place to start when looking at how to take great pictures.

Exposure is the amount of light that reaches the camera’s sensor and is controlled by three elements:

1. ISO - the sensitivity to light
2. Aperture - the size of the opening in the lens
3. Shutter speed - the amount op time that the shutter stays open for

They fit together in a triangle so changing one of the three elements will affect the exposure.

The best way I’ve seen this described is as a window.

The bigger the window (aperture) the more light is let into the room (the photo). The window has blinds - and you can change the amount of light by opening and closing the blinds at different speeds (shutter speed). You can change your sensitivity to the light by putting on a pair of sunglasses (ISO).

My camera allows me to control the ISO and the aperture (Av) or the ISO and the shutter speed (Tv) - when using either of these settings the camera controls the third point for me. Alternatively I can use M to control all three points of the triangle myself.

I’ll look at ISO, aperture and shutter speeds in separate posts.

Image via Wikipedia

Before I kick off with the ‘lessons’ I thought I’d share what equipment I use for my photography.

Camera

I upgraded from a point and shoot to a Digital SLR last year thanks to advice from my brother. He was sick and tired of me complaining I couldn’t take certain shots with my camera and politely told me that if I wanted good photos I needed a good camera and should just buy a DSLR! I’m not sure I completely agree with him - I’ve seen people take great pictures with a point and click - but I think if you’re going to take this seriously the DSLR is the way to go.

I didn’t want to lug around a heavy camera though so I’ve gone for an entry level DSLR which also suits my small hands. I am now the very proud owner of a Canon 400D (known as Canon EOS Digital Rebel XTi in the US).

Lenses

I have three lenses, the kit lens that came with the camera, a fixed lens and a zoom.

Kit lens

The kit lens is a 18-55mm f3.5-5.6. It’s not the best quality but it gives some flexibility when taking pictures

50mm lens

My brother convinced me to splash out on a 50mm lens to use for ‘everyday’ use - so far I’ve struggled with it! The quality is much better than the kit lens but I find it quite limiting. One of the things I’d like to do is learn when I should be using such a lens.

Zoom

The one thing I miss about the point and shoot is the great long zoom - so I just splashed out on a new toy - a 28-135mm f3.5-5.6 zoom lens. It’s big and it’s heavy but it lets me zoom in on the detail!

Bag

I carry all of this round in a small red Tamrac rucksack - I can stow my camera gear in a zipped area on the bottom and still have room in the top part for cash and keys and other paraphenalia.

Related articles by Zemanta

• Beginner’s Digital SLR buying guide: The Sifry Starter Photo Package
• Not Too Big, Not Too Small. Just Right?

I love photography and will happily snap hundreds if not thousands of pictures when I’m on vacation - but they never come out quite how I’d like them to! I have decided to put an end to awful photos and learn how to use my camera properly - if you too are a beginner and want to learn some camera tricks why not come along for the ride.