Photo tip - Basic camera functions

03rd January 2010
Photography can be baffling because there is so much to learn. Worry not! The key to learning anything is to prioritise the most important things so that you have a sound base. I want to lead you through the maze of information so that when you come to a crossroads you take the turning that improves your photos the most. And that’s what this is all about – better photos.

When you learn on your own (as I did) you learn more slowly, because you’re bombarded with information and you don’t know what to start with. I’ll help you learn the most important things first and then keep building on that knowledge with the next most useful tip.

The three key ingredients
I believe the three most important functions on your camera are:

- Shutter speed
- Aperture

This is because they influence the exposure, sharpness and depth of field of a photo. Let’s quickly look at each of these in turn.

Exposure: This is essentially how accurately the brightness of the scene has been captured. For example, if it’s a bright sunny day and the photo looks dark it’s underexposed. If a photo isn’t exposed correctly then it is unlikely to look appealing. There are times when you under or over expose on purpose, but that’s one of those more advanced rules you don’t need to know yet.

Sharpness: This is simply how sharp the image looks. You may laugh at the simplicity of this but a blurred photo is perhaps the most common mistake a beginner can make (unless of course it’s a creative blur!).

Depth of field: This refers to how much of the photo is in focus. Sometimes you want the whole image to be focused (which basically means sharp!), but often you will want to blur the background or foreground to remove distractions and ensure that your subject is the key part of the photo.

So you can see that if a photo is exposed well, sharp and creatively controlled through intelligent depth of field then you have a firm basis for a good photo. It’s now time to look at those functions I mentioned earlier (shutter speed, aperture and ISO) to see how we use them to create well exposed, sharp and creatively controlled photos. I like to use an analogy to explain how they all work in unison…

…filling a bucket of water
If you are filling a bucket with a hose pipe you could control how much water goes into the bucket by how long you turn the tap on for (shutter speed), how big the tap is (aperture) and how viscose the liquid is (ISO). So, if you turn the tap on for a long time through a wide opening and the liquid is watery then you will fill up a lot of the bucket. If you turn the tap on for a second and the hose is a small crack and the liquid coming through is honey then the bucket will fill up much slower.

This is how shutter speed, aperture and ISO work to control how much light hits your camera sensor. If you get the balance right then the photo will be properly exposed. So, working together these three elements create the right exposure, but they also have other uses…

Shutter speed – and avoiding blurred photos
The faster your shutter speed the more likely you are to have a sharp photo. The rule of thumb is this:

Look at the length of your camera lens (it will say something like 17-70mm, or 100-300mm) and make sure that your shutter speed number is at least as high as the lens focal length you are using. For example, if you are using your 17-70mm lens zoomed right out to 70mm then you would need a shutter speed of at least 1/80th of a second (a camera doesn’t have the option of 1/70th second!).

If you follow this rule and you hold your camera correctly then you should get sharp images, but ONLY IF YOU AND THE SUBJECT AREN’T MOVING. If either of you are moving then you need to increase the shutter speed. There are no hard and fast rules with movement as it depends on how fast and how close a subject is and whether it’s moving towards/away from you, or across your field of vision.

Aperture – Controlling depth of field
The aperture is the size of the whole that opens on the lens when the photo is taken. Just like the shutter speed the aperture helps control the exposure (the amount of light hitting the camera’s sensor), but it also controls how much of your photo is sharp and how much is blurred.

The aperture numbers are quoted in F stops. All you need to remember is that the higher the F stop number the more of the photo will be in focus. Awkwardly the higher the number, the smaller the aperture. So it goes like this:

- High F stop number = small aperture = more of the photo in focus
- Low F stop number = large aperture = less of the photo is in focus

Blur caused by a wide aperture is not generally a negative thing, unlike when you have blur caused by camera shake.

The first photo has a blurred background which enhances the image as the viewer’s attention is focused on the fox and its expression. Having a low F stop (a wide aperture) has helped achieve this. The second photo has more of the photo in focus (a greater depth of field) to show the fox in the background. A higher F stop (smaller aperture) has helped do this.

however, aperture isn’t the only thing that affects depth of field:

The nearer you are to a subject the shallower your depth of field will be and the further away you are, the deeper the depth of field will be.

Lens length
A longer lens (a telephoto lens, for example) will have a shallower depth of field than a shorter lens (a wide angle lens, for example).

Don’t worry about what it stands for (International Organization for Standardization if you must know!), just worry about what it does. It makes your sensor more sensitive to light. There are just two things to remember:

- The lower the number the better the picture quality and conversely the higher the ISO number the lower the quality.
- The higher ISO numbers give you a faster shutter speed.

Therefore you want to keep the ISO number as low as possible to give you the best picture quality. However, if your shutter speed gets too slow for the lens you are using (remember the rule I told you earlier in the shutter speed section) you will need to increase the ISO and sacrifice a bit of image quality.

A final word on the camera basics
Once you are comfortable adjusting these three settings to create sharp, well exposed images with varying depths of field you are ready for the next step. The next step is composition. This is because a technically perfect photo can still be dull if it’s not well composed.

Here are more of my tutorials that explain composition in various ways and for various subjects:

'Finding' photos:

35 Landscape photography tips:

Give your photos more impact:

Outdoor photography tips:

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