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Cardiff Camera Club

Photography is a wonderfully broad topic and takes many forms. For the great majority of people it provides a quick way to record memories of fun things like family holidays and parties. 

These days most photos are taken on camera phones or ‘point and shoot, cameras which will do a good job from which it is possible to print images up to A4 size.

However there may be times when one wants an image that larger or a bit more special. Many of us also find it more rewarding to take control and not let the camera’s computer do all the thinking.  

General Tips

First you need a digital camera but take care before you part with your hard earned cash! There is a bewildering array of cameras on offer. So please come along to our club first, its free for the initial 3 weeks) join and clear your mind. 

If you really cannot wait to buy do remember that however fancy the camera body seems, it  will not make a good image with a poor lens. This is particularly important when you are buying a dSLR – see our camera guide here.

Secondly, for best results, you will need a computer. Actually, you need a computer programme that is designed to manipulate computer files. Just about everybody has heard of Adobe’s Photoshop. But there are also very powerful less expensive or even free alternatives – see our software guide here

These programmes are relatively easy to master, other more difficult. Most come with an instruction manual or with in-built ‘help’ menus. 

Technical Principles

We will take it for granted that you had enough time to read the manual, and know where the controls are!

Cameras nowadays are computers, and whilst they differ in many ways from film cameras they are in one respect very similar. Essentially they are  box which contains a sensor (or film) to capture an image. They both have a hole to let the light in; a shutter to control how long the hole is open and use a lens to force the available the light to a sensor at the back of the camera. 

All we need to know is what to point the camera at, how big to make the hole (which we call an aperture because it sounds nicer), and how long to leave the hole open.

Rekjavick Cathedral by Vic Chambers

Painting with light.

Photography is often referred to as ‘painting with light’.  Basically you create an image by controlling the amount of light that hits the camera’s sensor. In automatic (auto) or program ‘P’ modes the camera does all this for us. The camera computes what it thinks are the optimum settings for the shot you have identified throughout the camera’s viewfinder.

But what if the scene is lit by street-lamps at night in the snow and we don’t like the camera’s response?  And what if we want to make a picture where water looks like a white sheet, or freeze the action of a fast moving object? What if we want to take a portrait and make everything behind the subject appear out of focus?

To have some control over these you need to understand three basics:

  1. how the sensor works and how to control the amount of light it receives 
  2. what the aperture does and how, by changing the settings, it produces different results
  3. how to change the shutter settings so than when you activate the camera it lets in just the right amount of light.

Now we put all three together – sensor, aperture and shutter speed.  Tutors have tried all sorts of imagery to explain this, and one of the better ones is the idea of water instead of light.  In this analogy the sensor is a bucket, the aperture is the diameter of a hose pipe that goes into the bucket, and the shutter is a tap. 

The idea is that in order to get an image you need a ‘bucket full of water’ that is being constantly filled.  To achieve this you could have a small bore pipe and turn it on for a long time or a wide bore pipe and turn it on for a shorter time.  So once you have decided how much water is needed in the bucket, you can choose whether to have a wide aperture and short burst of water, or a small bore aperture and a longer burst of water.

Controlling how the camera’s sensor reacts to light.

The camera’s sensor is probably the most expensive part of the camera. Its job is to control the intensity available light on your camera. The speed that the sensor reacts to light is measured by what is known as ISO (pronounced eye-so). 

In very basic terms ISO is the level of sensitivity of your camera to available light. With increased sensitivity, your camera sensor can capture images in low-light environments without having to use a flash, and with decreased sensitivity, it can capture images that are very bright.

In ordinary good daylight (outdoors) an auto setting uses something in the region of ISO 100 to 400.
To shoot indoors or in low light you might need to turn up the setting to 1600 (or more). But this comes with a penalty: basically the camera is trying to record an image with less and less light – so it becomes less sharp and less colour saturated. Sometimes there is not enough light to make the sensor’s pixels work to their optimum strength. As a result, the image may appear slightly degraded. This photographers call ‘noise’

ISO numbers follow an incremental sequence, ie 100, 200, 400, 800 and so on.  Turning the setting up one notch will cause the camera react to light twice as fast as its previous setting, and turning it down a notch will reduce it by half. Each number doubles or halves its neighbour.  

Controlling the ISO has a direct link to how apertures and shutter speeds link together, and is the first of these three essential elements to remember.

How do you decide what is the total amount of light you need on the sensor ?  This is where the light meter comes in.  Nowadays most cameras have a built in meter which is visible either through the viewfinder, or on the camera’s rear monitor if it has one. Generally speaking, you will see a ‘plus and minus’ scale ( – ……….  I  ………. +) with a required centre point which can be adjusted. You can find out how to do this in your camera manual.

Aperture.

You will often hear photographers talk about ‘f ‘ numbers. But what are they?

The ‘f ‘ stands for focal point.  This is an imaginary point somewhere in the image that determines whether only part of the image is rendered sharp, or whether all of the image appears equally crisp and sharp. This is often feared to as depth of field. 

These strange numbers basically control the size of the aperture and thereby how much, or how little, light reaches the sensor.  Low f-number indicate the use of a large aperture, high ‘f’ numbers indicate the use of a small aperture.

Photographs taken with a low f-number (large aperture) will tend to have subjects at one distance in focus, with the rest of the image (nearer and farther elements) out of focus. This is frequently used for nature photography and portraiture because background blur emphasises the main subject in the foreground.  

Photographs taken with high ‘f’ (small aperture) area mostly sharp throughout.

Depending on the type of camera being used (and its cost) ‘f’ numbers will rage from  f1.2, f1.4, f1.8, f2.0, f2.8, f4.0, f5.6, f8.0, f11.0, f16, f22 and so on.  Each increment accounts for a ‘one stop’ difference. (On cheaper cameras the range of stops will be much smaller and start part way along this scale).

In practice photographers just remember that each of the ‘one stop’ numbers lets in half the light of the next higher number in the sequence.  So 5.6 allows in half the light of 4 much the same as it does with ISO settings.

Shutter 

Fortunately, shutter speeds are self evident. What you dial in is what you get unless you use the ‘B’ setting. (B stands for ‘Bulb’) which keeps the shutter open all your finger is on the ‘click’ button.  

Sutter speeds are shown as a measurement of time (in seconds or fractions of a second) 1 s, 1/2 s, 1/4 s … 1/250 s, 1/ 500 etc. etc.

The important thing to note is the faster the shutter speed – the shorter the time the image sensor is exposed to light; the slower the shutter speed -the longer the time the image sensor is exposed to light.

If, for example, you are photographing a subject that is in motion, you will get different effects at different shutter speeds. Fast shutter speeds will ‘freeze’ motion, while slow shutter speeds will cause some blurring.  

If you photograph moving water for example a fast shutter speeds will ‘freeze’ it, while slow shutter speeds will create that milky effect.

Once you know how this works you can apply different effects to create motion blur.  Not all blur however is created way. Unintended blur maybe due to camera shake which can only be prevented by holding your camera steady or by using a tripod.  To see how this works find some moving water (a stream or waterfall) and take the same image at different shutter speeds and note the difference. 

If you want to try out an on-line programme to see how these settings relate to one another take a look at  Camera Simulator -a website allows you to try various camera settings to see the effect on the final image.

Decision Time

How do you decide what is the total amount of light you need to get that perfect picture on the sensor/film?  If you taking photographs out doors on a reasonably clear day set your camera.

  • Aperture to F9, 
  • ISO to one hundred 
  • Speed to 1/125

If this turns out not to produce good enough results sort by adjusting one element until you have that perfect shot. 

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