Using a Budget Digital Camera for Teaching, Learning and Research

Last updated: 12 February 2008
Published in: Digitising analogue media | Creating new digital media | Finding and using digital media
Tags: cameras | photography

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Summary

Over recent years the price of digital cameras has tumbled while there has been a corresponding improvement in image quality. Compact digital cameras are compact flexible devices that work well in the modern workflow. This document provides an introduction to the compact camera and how to get the most from it.

Contents

1. Introduction
2. The compact digital camera
3. The budget SLR camera
4. How analogue and digital compacts are alike…
   • 4.1 All cameras need light
   • 4.2 Remember to use good basic camera skills
   • 4.3 Looking after the image once you have shot it

5. ...and how digital cameras are different

   • 5.1 Image area
   • 5.2 Power
   • 5.3 Expense and fragility
   • 5.4 Digital cameras in operation
   • 5.5 Special skills required for digital cameras
   • 5.6 Image management
6. Conclusion

1. Introduction

Many digital imaging projects may not have the budget for a high-end, or ‘prosumer’ camera.  Users involved in teaching, research or fieldwork may find that there is a pragmatic need for ‘cheap and easy’ capture of a range of subjects, for which they do not need the highest quality.

For these types of project, a mid range or consumer digital camera can often provide enough quality to fulfil its needs.

Diagram 1. A typical compact digital camera

The development of these digital cameras, in terms of quality and functionality, is fuelled by demand from the consumer market, which has lead to a very fast development in the last few years.  At present both entry-level digital SLR (Single Lens Reflex) cameras and good quality compact digital cameras can be purchased from around three hundred pounds.  Before you rush out and buy a camera though, it is important to understand the differences between compact and SLR cameras.

2. The compact digital camera

To reduce the camera size and keep the price down, compact cameras use a simple optical viewfinder or digital display rather than the complex optics of an SLR camera. The compact camera’s optical viewfinder uses a different lens system to that used to take the image, and so there can be a disparity between the scene as viewed through the viewfinder and the captured image. While this disparity might be unnoticeable at the wider focal lengths, at the longer end of a zoom or for close up work the difference can be quite obvious.

At first digital cameras were fitted with LCD screens to help the user to navigate through the complex menus and features of a camera. Over the years, these screens have evolved and now allow the user to review stored images and act as a digital viewfinder. Digital viewfinders though, do place a significant demand on the battery and they can be difficult to view under bright light. To further reduce the size and price of digital compacts some manufacturers have removed the optical viewfinder altogether from their smaller cameras.

Compact digital cameras normally have fixed lenses; additional ‘clip on’ lenses can be attached which cover focal lengths unavailable in the standard camera configuration.

Advantages

• Small and highly portable
• Simple operation
• Basic cameras are cheaper than digital SLRs

Disadvantages

• Limited range of accessories
• Limited features
• Lower quality than equivalent SLR

3. The budget SLR camera

The SLR camera uses a complex optical system to help the user compose the scene and verify focus. This does however make the SLR significantly larger than the average compact camera. In recent years the consumer digital SLR market has expanded dramatically and there are now cameras to suit most budgets.

Diagram 2. A typical digital SLR camera

Advantages

• Highly flexible system
• The photographer sees exactly what the camera will capture
• Greater control over image capture, exposure and focus

Disadvantages

• Larger than equivalent non-SLR camera
• Dust can enter camera during lens changes
• Noisier operation than non-SLR camera
• Huge range of controls can scare the novice

Of course we don’t intend to go into the specific features or individual workings of each camera, for that you will need to check technical specifications and user instructions.

For further information on Digital SLRs see JISC Digital Media’s report on The Digital SLR Camera for Teaching, Learning and Digitisation.

4. How analogue and digital cameras are alike…

4.1 All cameras need light

All cameras, whether digital or film, rely on light to make their images and generally in normal use, the more light the better (within reason). If you are trying to improve the quality of your images, then first of all make sure there is enough available light.

Of course, the quality of the light will also make a fundamental difference to the look and feel of your image although an internal flash, daylight and tungsten studio lighting all give ample light and fine quality, the resulting images will all look different. It is up to you to make a ‘creative’ choice as to how you want the image to look and to use an appropriate light source to achieve this.

Diagram 3. Comparing a range of light sources

The camera’s built in flash produces harsh shadows behind subject.

Diffused light from a North-facing window produces very soft shadows.

Domestic tungsten light above subject produces soft yet defined shadows.

To start with keep the main light source behind you. As you become more confident or creative you could try other positions. For most applications though, it is best not to shoot directly at a bright light.

Diagram 4. The effects on the image of changing the direction of lighting

(Left to right) 1. Lighting from behind subject; 2. Direct lighting from the camera position; 3. Lighting from the side (left)

When lighting your subject, remember that the more directly behind you the light source is, the flatter the lighting will be. The more ‘side-lit’ the subject is, the longer the shadows will be and the more feeling of depth will be conveyed.

If a point light source is used (sun, lamp, etc.) the shadows will be hard edged with little detail within them. However if the light source is large and broad (sky, lighting umbrella, etc.) the shadows will have soft edges. A point source can be softened by diffusing it with translucent material or by ‘bouncing’ it of a white surface.

Diagram 5. Images taken with soft and hard lighting

With soft lighting the shadows are subtle (left); With hard light the shadows are strong and clearly defined (right)

To get good results with any camera (digital or film) you will still have to master the same range of basic photographic skills:

• Keep the camera steady
  One of the best ways to ruin your photos with any camera is to move it whilst you are taking the shot, so remember to keep the camera as still as you can. Under bright light you will normally have a fast shutter speed so camera shake should be minimised. Under lower light levels or when using a slower shutter speed consider using a tripod to keep the camera stable. Using a support will not only make your photos sharper, but it can also help you to concentrate on the content of your image; which will lead to the shots being more reliably framed and focused.
• Remember that long (telephoto) lenses are harder to use
  Long lenses give only a small angle of view, and any small movement of the camera will easily be exaggerated, possibly harming the quality of the image. Therefore it is important that you keep the camera steady (preferably using a tripod).
  
  Long lenses also have less depth of field and are less efficient at transmitting light. This is less of an issue for compacts than it is for SLRs, but still applies if your compact has a zoom lens. The longer the lens, the more important it becomes to ensure that you also have enough light.
• Problems with flash
  If you can adjust the flash, make sure it is angled in such a way that the light it casts does not cause unwanted reflections, glare or shadows. Of course, if the camera uses a built-in flash you might not be able to adjust it at all. On the other hand, it might still allow you to capture an image that would otherwise be impossible. The output of some built in flash units can be adjusted to complement the ambient light rather than overwhelm it. Some cameras also offer flash controls to reduce the appearance of ‘Red Eye’ when photographing people.
• Composition – think about what you are shooting
  An old adage of professional photography states: “there are only four important things in an image - the top, the bottom, and both sides.” It is easy to get carried away with the excitement of what you are shooting, so always make a conscious effort to remember to look around the four edges of your image. Make sure the horizon is straight and nothing important is falling out of the image. After a while this skill becomes second nature and hopefully you will no longer take photos that cut off your subject at the edges.
• Be aware of the viewfinder’s accuracy
  With most compact digital cameras, checking the content of images is not made any easier by one of their most annoying features: their optical viewfinders are very inaccurate. This is because the optical viewfinder is normally offset from the lens itself and therefore cannot give a ‘through-the-lens’ view. This in turn means it cannot give an accurate visual representation of the image area you are capturing, especially when shooting an object at a distance or very close up. Most digital compacts overcome this problem by using a LCD screen to preview the image from the CCD, although even these have a habit of losing the outer edges of the image (showing approx 90-95%). However, in most cases this is still more accurate than the offset viewfinder. The digital SLRs provides a real advantage over the compact cameras, by allowing the user to look directly through the lens before the image is taken, thus providing an accurate visual representation of the image area.

4.3 Looking after the image once you have shot it

With a traditional analogue camera, it is important to look after the camera’s film both before and after you have exposed it (protecting it from light, heat and even x-rays). With a digital camera it is still imperative to protect your images, although it is now the memory cards that must be handled with care.

These cards (e.g. Compact Flash, SD cards, Sony Memory Stick, and Microdrives), can all be easily damaged by magnetism, physical knocking, high frequency transmission from walkie-talkies or mobile phones, and even by the electron beam irradiation used by the US postal office to search for Anthrax!

However, without doubt, the biggest danger to memory cards is the camera operators themselves. It is only too easy to mistakenly delete images before you have safely moved them onto a secure long-term storage device. It is therefore very important to establish and implement a safe workflow that enables you to reliably back up your images from the camera.

5. ...and how digital cameras are different

There are some important differences between film and digital cameras that need to be discussed:

5.1 Image area

With all cameras it is good practice to make sure that you fill your frame with your object, there is no point in using image area if you are just going to crop it out afterwards. With a digital camera the quality (and therefore cost) is directly related to number of pixels and you really do not want to throw any away. Therefore this good practice becomes an imperative demand. However lens distortion is more obvious towards the edges of the frame, particularly at the lower focal lengths (wider angles) and so filling the sensor may give the edge of the object a distorted appearance.

5.2 Power

Digital cameras are crammed with electronics undertaking a vast amount of processing, which tends to drain the camera’s batteries very quickly. This is particularly true with the more common CCD-based cameras. The new generation of CMOS-based cameras undertake more processing on the chip, however, which ultimately makes them less power-hungry. For further information on CCD and CMOS see JISC Digital Media ‘s report on Digital Cameras.

Camera manufacturers are striving to develop cameras that are less power-hungry whilst simultaneously developing more powerful batteries. Until this happens, there is not a great deal you can do except to buy the best and most powerful batteries you can, and to always make sure you carry spares with you. Remember that the biggest users of power within the camera are the LCD viewing screen, the flash and the zoom functions, so if you are worried about power, it is normally best to avoid using these functions any more than you have to.

Most digital cameras use their own proprietary rechargeable batteries that are not as widely available as AA sized batteries. It is therefore wise to have at least one fully charged spare and the charger with you at all times.

5.3 Expense and fragility

Digital cameras can be very expensive highly complex instruments that are crammed full of electronics, which tend to be temperamental, unreliable and horribly fragile. However, camera design is moving fast towards providing more functionality ‘on-the-chip’ (mainly using CMOS image receptors), which should provide more reliable and cheaper cameras.

No matter how cheap or robust a camera may seem, do make sure it is properly insured and fully covered by the manufacturer’s guarantee. Also look after your cameras carefully – don’t leave them anywhere wet, humid or dusty, and don’t leave them in direct sunlight.

5.4 Digital cameras in operation

• Shooting speed
  Compact digital cameras may be slower to operate than their film-based siblings. Firstly because there can be an annoying delay (or ‘shutter lag’) between pushing the shutter button and the camera taking the shot, and secondly because there can be a long wait between taking one shot and the next, while the camera processes and saves the image. These delays are less of an issue with some of the newer, more expensive compacts, and absent from most digital SLRs.
• Functionality and menus
  Budget cameras tend not to have many physical switches. Most functions and controls are found within a hierarchical menu system accessible via a small LCD control screen. This can make the camera painfully slow to use as you find yourself hopelessly lost within a myriad of interlocking menu systems. Although these menus often provide a lengthy list of special functions, navigation around them can be both frustrating and very time-consuming.

5.5 Special skills required for digital cameras

• Shutter lag
  As mentioned above, shutter lag is an effect common with older and cheaper digital compact cameras, where there is found to be a delay between the shutter button being pushed and the shot being taken. The effects of shutter lag can be very annoying but there are a few things you can do to help minimise the delay.
  
  Shutter lag occurs while the camera is focussing, setting white balance and exposure metering, so if you can set some of these functions before you push the button, you should reduce the lag. Most cameras will pre-focus if you depress the shutter button halfway.
  
  Once you have got used to the way your camera works, you can try to pre-empt shutter lag and push the button just before you want the picture to be taken, although this is still pretty hit-and-miss. Luckily technical advances in digital cameras are making shutter lag a thing of the past, but it is certainly something that should be considered when deciding which model of camera to buy.
• White balance
  All cameras (film and digital) attempt to give an honest and objective interpretation of the colour they see in front of them. However, in reality the colours of objects are continually changing depending upon the type of light, and its inherent colour temperature, that is illuminating them.
  
  When we see these objects with our eyes, our brains do a fine job in hiding the differences and providing colours which our brains ‘know’ are right (so white paper appears white even if we are viewing it under candle light - when it is, in reality, bright orange).
  
  With a digital camera we can of course always correct the colour of the image after we have shot it during image optimisation. It is, however, much better to make sure that the colours are as correct as we can make them before we take the picture.
  
  This is done by establishing the ‘white balance’ or ‘doing the greys’. In both cases this means pointing the camera at something white or grey, which allows the camera to read the colour of the light it sees and neutralise it to a white or grey, thereby correcting all the other colours at the same time.
• Compression
  There was a time when computer memory was very expensive. Indeed, with early digital cameras one of the main production costs was the memory used to store the images within the camera. This led to camera manufacturers trying to cram as many images as possible onto the expensive memory cards. To do this they had to use quite heavy JPEG compression, which unfortunately tended to have a rather detrimental effect on image quality.
  
  Most digital compacts are better these days, providing a better quality file at a larger file size. But on the whole, the biggest single reason for low quality in images from digital compacts is the over-zealous use of JPEG compression.
  
  There are three possible ways around this:
  1. If the camera allows you (and you have enough space on your memory card) save the image as an uncompressed TIFF file. This will preserve all the original image information and is the best option if you want the finest quality. There are a few snags though: it uses up storage space much quicker; processing and saving that amount of data takes much longer giving slower operation; and only the more expensive models allow you to do this.
  2. Some cameras, again the newer and more expensive ones allow you to save the image data in the raw form in which it was captured. This gives you all the image quality (exactly as it was captured) but with a smaller file size than TIFF. You can then use the RAW file at a later date to make your TIFF file. This approach is widely available in digital SLRs, but is also available with some of the better compact cameras.
     
     One snag with this approach is that you cannot view or use this file (which is at this stage in a proprietary form) until you have processed it and created (by interpolation) the full image file within a standard file format. Of course best practice would suggest that you should archive the image in a non-proprietary format such as TIFF and also the original RAW format.
  3. Most cameras allow you to choose from a range of quality/compression levels when you shoot. Remember that compression will allow you to store more images but will also throw away some image quality, so use with care.

5.6 Image management

One of the fundamental differences between digital and film cameras is caused by the form the created images take. A film camera gives you some form of physical ‘real-world’ image (e.g. print, transparency, negative), while a digital camera creates a virtual image that does not physically exist (until it is outputted to print or monitor).

This difference has implications when it comes to image management. Physical ‘real world’ images can be stored easily in physical ‘real world’ containers but a digital image must be stored within some ‘virtual’ container, which is much harder to visualise and organise. It is important for physical images to be carefully indexed and filed, for the digital images it is not only important, but absolutely imperative if you are ever going to be able to find the ‘virtual’ images from the depths of your hard-drives. Your ability to find any image once it has been removed from the camera will depend almost entirely on the metadata that you record for it.

In its most rudimentary form the metadata may simply be the filename given to each image. If the file naming system you choose is of the descriptive kind (see JISC Digital Media’s Choosing a File Name document for further information), the filename alone may provide enough information to navigate around a small collection of images. However, additional metadata becomes key (while the filename takes on less significance) once the images are stored in an image management system.

Most digital cameras now automatically capture a range of useful metadata within the image as it is created. Technical details, such as the time the shot was taken, exposure settings, camera make and lens information, can be automatically collated and stored within EXIF (EXchangeable Image File) ‘tags’ on the header of the image file itself. Further information can also be held within a similar range of tagged metadata fields defined by the IPTC (International Press & Telecommunications Council).

This approach to storing metadata might appear to be the answer to the problem of identifying images, however, as ever there are problems with this approach. It is unwise to rely on image tags alone – especially while only some applications fully support EXIF and IPTC data. The risk is that tags can be wiped completely if an image is opened and saved in a non-supporting program.

Further information can be found in JISC Digital Media’s documents on Choosing a File Name and Metadata.

6. Conclusion

Digital cameras get cheaper by the day, and advances in camera technology continuously give us gains in quality and functionality. Providing you are clear about your project’s requirements, and use the guidelines outlined here, getting to grips with a digital camera should be quick and easy.

Although it is common knowledge that the high-end professional digital camera can easily provide quality exceeding that of traditional film cameras, it is also evident that a budget camera, if used correctly, can provide easy and pragmatic capture of digital images at an acceptable cost. The quality will not match what is available from high-end cameras, but will often provide an image of sufficient quality for many uses.

Last updated: 12 February 2008
Published in: Digitising analogue media | Creating new digital media | Finding and using digital media
Tags: cameras | photography

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