Watch the Birdie! - Starting Digital Photography Quiz

Answer: The sensor

Perhaps surprisingly, the component at the heart of a digital camera is analogue equipment. The sensor, which is made of a photosensitive material, stores light as tiny electrical charges. The camera processes this information by passing it through an analogue-to-digital converter and it is at this point that the digital camera actually lives up to its name.

The two most widely used sensors, the APS-C (DX) and Full Frame (FX) formats, are both used by the two big-hitters in the camera industry - Nikon and Canon.

The smaller APS-C sensor, at 24mm x 16mm in size, is aimed primarily at the beginner and enthusiast markets whereas the larger FX sensors at 36mm x 24mm (approximately the same size as a frame of traditional camera film) are used in equipment aimed squarely at the professional photographer... With price tags to match! However, larger does not necessarily mean better. One advantage of using the APS-C sensor is that the crop factor of these smaller sensors results in a virtual increase in the focal length of the lens in use; for example, the 1.5 crop factor on my Nikon D300 increases the focal length of a 50mm lens to around that of a 75mm lens.

This gives me more reach, but does mean that a little more thought to framing the shot is required on my part. The third example of sensor, the 'Live MOS', is a low power sensor used in cameras manufactured by the Olympus, Panasonic and Leica brands designed to extend the camera's battery charge.

Answer: Macro

A macro lens is defined as any lens that projects an image in the scale of 1:1 onto the sensor at its closest focusing range and which, at this distance, fills the entire frame; lower specification macro lenses that capture images at 1:2 on the sensor are also available. Alternatively, similar results can be achieved without the expense of purchasing a specialised macro lens. For comparatively little cost, the photographer can equip his or herself with a set of bellows or a series of extension tubes. These can be used in conjunction with a standard lens to extend the focal length; for example, an 85mm lens with a single 20mm extension tube will produce similar results to those of a 105mm macro lens. The resulting images will not be quite as fine but will be acceptable nevertheless. The lens that I use for macro photography in the picture is a 105mm f/2.8 manufactured by Sigma which, for what it cost, is probably one of the best macro lenses currently available.

Prime lenses are very high quality lenses of fixed focal length, usually in the range of 20mm to 50mm, and used primarily for portrait work. Fisheye lenses possess very short focal lengths in the range of 8mm to 14mm and use highly convex lens elements in order to achieve special photographic effects.

Answer: White balance

Many cameras provide the photographer with a function that enables them to correct colour imbalances under various lighting conditions; this may be a manual control on the camera body or an option hidden away somewhere amongst a plethora of menus. The 'WB', or white balance control, is used to correct any colour cast which may be detected by the sensor but indiscernible to the human eye. Images taken under sodium lighting may possess a feint orange coloured cast and the function of the white balance control is to cancel this out. Shooting under fluorescent tube lighting may produce a bluish cast but this can also be corrected by using the white balance controls on the camera.

The closest artificially produced light to natural direct sunlight is that produced by many camera flash units.

Answer: Sensitivity

Known as 'ASA' in the days of film and often referred to by photographers as the film 'speed', the modern ISO settings, presented as linear and logarithmic numbers, are a standard measure of a sensors sensitivity to light. ISO, the initials for the International Organisation for Standardisation, established the standards for digital camera sensors in 1998.

Imagine that you wish to take a picture of the Milky Way on a beautifully clear night. Firstly, you need to ensure that you are well away from any sources of light pollution. Secondly, you'll need a good quality lens with a large aperture setting in order to allow as much light as possible onto the camera sensor; remembering that your shutter speed may well be upwards of eight or ten seconds it is imperative that the camera is mounted securely onto a tripod. Finally you need to set the ISO... If your 'glass' is good you may be able to achieve great results with an ISO setting as low as 600 or 800, but anything between 1000 and 1600 is more likely. Photographers just starting out will be tempted to set their camera to 'auto' and hope for the best, but this is missing the point (and is unlikely to work anyway) as the trial and error method is a great, fun way to learn. Dialling in too high an ISO setting introduces a form of degradation (noise) into the final image; not an issue if your pictures will only be viewed at low resolution but irritating if you wish to enlarge them at a later date. In bright shooting conditions your ISO setting is not as critical and can be set as low as 100 or 200 as the amount of light reaching the camera sensor can be controlled using your lens aperture settings and the camera shutter speed.

Answer: Rule of 500

Images showing star trails can be attractive and interesting and often simply leaving the camera on a tripod with its shutter open for periods of fifteen seconds or more can produce the desired effect. In other cases we may simply want to see small points of light in the image to represent more realistically how we see the stars with our own eyes. To achieve points of light you can use a simple rule called the "500 Rule":

Take the number 500 and divide it by the focal length of your lens = the longest exposure time, in seconds, before the stars begin to develop trails.

For example; let's say you're taking a shot of the Pleiades cluster with a 24mm lens on a full frame camera. Take 500, divide by 24 which gives a result of a shutter speed of 21 seconds, which you should round to 20 seconds; many cameras will not enable a period as specific as 21 seconds to be selected. However, if the photographer wishes to be truly accurate they might use an electronic release but this may also necessitate the use of a stopwatch. Although it is called a rule, it should be looked upon more as advisory or a guideline; there are many other factors out there that can, and will, have an influence on your final results.

Answer: Aesthetic blur

Clearly there is a difference between the blurring and softening used deliberately to enhance the aesthetic quality of a picture and the blur that is often seen when the careless photographer simply takes a poor photograph - we've all been there! The term' bokeh' is used to describe the aesthetic effect of the blurring behind the object of a photograph as can be seen in my example; the rose is sharp but the background has been softened to provide an attractive contrast to the bloom itself. In real terms, the quality of any bokeh is directly related to the size of the aperture and in my example this was achieved by using a medium aperture setting at f/4.5 and a shutter speed of 1/80 second.

Similar results may also be achieved in post production through the use of image editing software such as Photoshop... But that's cheating!

Answer: f/1.8

The 'f' number, or 'f' stop, is defined as the ratio of the focal length of a lens to the diameter of the aperture setting being used to take a particular picture; for example, an 'f' number of 5.6 means that the focal length of the lens at that setting is 5.6 times the diameter of the aperture in millimetres.

This is the reason why the majority of lenses with large aperture settings tend to be of a short focal length. Those photographers who wish to capture the majority of their images in low light conditions should always have a lens with a maximum f-stop setting of at least 2.8 in their equipment bag; f/1.8 would be better and f/1.4 better still but lenses like this, commonly referred to as 'prime' lenses can prove to be incredibly highly priced, especially for the amateur photographer. Those photographers looking to move up to telephoto lenses with large apertures had better brace themselves for a shock and have deep, very deep, pockets.

A Nikon 200mm telephoto lens, which will not produce a particularly impressive level of magnification, with a maximum aperture setting at f/2.0 will see little, if any, change from £5000 or $6500!

Answer: Filter

UV means Ultra-Violet, ND and ND Grad mean Neutral Density and Neutral Density Graduated respectively, whilst CPL are Circular Polarising Lenses. The vast majority of UV filters purchased by photographers today are bought simply as a means of protecting the expensive glass components of their lenses.

Modern digital camera sensors are protected by integral UV and IR filters thus rendering external UV filters obsolete. Both ND and ND Graduated are filters designed to enhance the contrast between different areas of a picture such as improving the definition of clouds against the backdrop of a relatively bright sky; those designated ND are of a single uniform shade of varying densities whereas graduated filters are, as their name suggests, darkest along one edge becoming less so towards the opposite edge. Circular polarising lenses consist of two components, a securing ring and a rotating disc of special glass.

They are a type of adjustable filter used to reduce reflection and glare when shooting on or near highly reflective surfaces such as water or snow.

Answer: Rule of Thirds

The human eye, when looking at an image, will be naturally drawn towards a position around two thirds of the way up the page... At least that's the theory. An image may be divided into thirds either horizontally, vertically or diagonally. If the photographer wishes to emphasise the sky and the clouds it is likely that they will frame the image so that the sky will occupy the top two thirds of the page; alternatively the horizon might be placed two thirds of the way up the page emphasising the colours of a landscape or seascape. One effect that I like to use is to set my horizons at an angle of between twenty and thirty degrees... I remember a recent picture taken of a Royal Navy frigate that looked as if it was about to fall over the edge of the world! Depending on my mood at the time, I may also try to orientate my pictures at the same angle as any hills, cliffs or other interesting features might appear in the landscape; this may result in an image in which a feature might occupy the space from the centre bottom edge to the top left of the image. Providing that the photographer remembers to apply the rule of thirds, not necessarily rigidly but in some measure of its spirit, the possibilities are myriad and good, interesting images with artistic flair can be expected.

Answer: Aperture

The Exposure Triangle is the term used to describe the interaction between the three fundamental elements of exposure: aperture, shutter speed and ISO, and in the way that the three combine to produce great images, especially when biting the bullet and venturing into using your camera's more esoteric modes of operation.

For example, increasing the ISO setting for whatever reason might result in the photographer reducing the size of the aperture and increasing the camera's shutter speed or, alternatively, an increase in the size of the aperture will require a reduction in one or both of the other two in order to maintain the correct exposure. Balancing the exposure triangle is an art in itself and deciding on a change in one element inevitably means a compromise has to be made with one or both of the others - it's a great way of taking complete control of your camera and producing exactly the images that you want and not what the camera thinks you should have!

Answer: Digital noise

Measured in decibels, digital noise is the visual manifestation of a low signal-to-noise ratio and is often noticeable in post-production when the photographer may become aware of an unacceptable graininess in their images when magnified; if you enlarge the image in the example and zoom into the areas of sky, the digital noise can be quite clearly seen. Higher ISO settings, which you may need when shooting in low light, are the main culprit in causing excessive digital noise. Think of your ISO settings as you might as the gain pot on an electric guitar amplifier... Dial in more gain, the louder the sound becomes, but it also becomes distorted; in a photograph, the higher the ISO setting, the more this distortion or digital noise, shows in the image. Cameras with smaller sensors, such as cell phones and compact cameras have thumbnail-sized sensors, and with these cameras noise can reach unacceptable levels even at levels as low as ISO 400. Cameras with larger sensors, such as DSLRs and mirrorless interchangeable-lens compact cameras produce lower gain at higher ISOs.

Answer: RAW

RAW file sizes can be huge, sometimes running into many tens of megabytes per file. This can cause issues when shooting multiple frames as many cameras, particularly those aimed at the casual or keen amateur markets, are incapable of processing such file sizes at high speed, which often leads to buffering issues. My Nikon, fitted with a 64Gb compact flash card, is capable of storing up to 4,300 images using JPEG file types but this falls to a mere 1,500 when using the RAW file type.

However, the RAW file type comes into its own during the post-production process; whereas JPEG file types can only be manipulated to a very limited degree such as in red-eye removal, cropping, and the use of a general enhancement setting, the manipulation possible with RAW files can be incredible depending on the software package that the photographer has at their disposal. Parameters such as the overall exposure can be adjusted as can fill light, temperature, saturation, contrast and clarity settings. When you have RAW files at your disposal the world really is your oyster.

Answer: Saturation

In purely layman's terms the saturation of a colour is a measure of its intensity or purity. The more saturated a colour is, the more intense it appears and vice versa. As any colour, take green for example, becomes gradually desaturated it appears more and more grey until complete desaturation means that it contains no green whatsoever and it appears as a grey tone - black and white images are considered to be completely desaturated.

Answer: Manual

Of these four settings groups, the most widely used is 'Program' which is also often referred to as 'Auto'. With this setting the photographer allows the camera itself to automatically select the optimum settings for the conditions at that moment in time. By selecting 'S', or 'Shutter' the photographer is instructing the camera to give priority to shutter speed; selecting 'A' for the 'Aperture' setting gives priority to the size of the aperture.

The most complex of all is the 'M' or 'Manual' setting.

This command is for those photographers who wish to take total control of the camera and all of its shooting parameters. Because of the possibility (or likelihood!) of catastrophic errors being made using this option, it is more probable that this setting will only be used successfully by professional photographers or keen and experienced amateurs.

Answer: Depth of field

The depth of field of any image is directly affected by the size of the lens aperture when the image was taken. Low f-stop numbers, those with large apertures, will result in a very shallow depth of field and a degree of bokeh. Higher f-stop numbers, with smaller apertures, will result in a much greater and more sharply defined depth of field. F-stop numbers at the lens maximum will result in a depth of field so great that everything framed within the image will be sharply in focus. Another factor that will have an effect on the depth of field is the distance between the camera and the subject. Getting to within a very short distance of the subject will reduce the depth of field to just a few millimetres and this effect can be seen in the example provided; my point of focus is on the insect's thorax and this is in sharp focus. If you look both forward and to the rear of this point you will see that the subject becomes slightly blurred. This insect, a damselfly, is only around 45mm in length so it can be deduced that the depth of field in this picture is little more than 7 or 8mm.

It is surprising to think that, numerically, the difference between the numbers 1.4 and 3.0 is not too great; but when it comes to f-stop numbers, the differences in results can be remarkable!