(Editor's note: This article was originally published on March 7, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
In many avenues of our modern lives, it can pay to remember that computers are completely & utterly stupid. They may do many things simultaneously & do them very quickly, but they will never be lateral thinkers, talented artists or great photographers. For this reason, photography is one pursuit in which what you pay for is not always what you get. When it comes to taking a good picture, any old manual camera can easily produce better results than even the latest & most expensive automatics. This is because everything that matters happens in the mind of the photographer, rather than in a microchip.
Whilst only a person can take great photographs, there are basic concepts that must be properly understood to get the most out of a camera. Knowledge of film speeds, aperture & shutter speeds, plus the different ways these variables can be balanced to create stylistic & original pictures, is what photography is all about. This becomes especially true in the garden, where subjects may be poorly lit, situated problematically or just plain small & easily lost in the background. By applying photographic skills to these subjects, difficulty will readily become originality with some surprisingly good results.
Some old favourites.
In photography, the term ISO refers to the speed of negative materials. Previously, this was known as ASA. Like many photographic concepts, this variable concerns the interaction of light with the camera (particularly, the sensitivity of film or digital sensors to exposure). "Faster" or higher ISO film allows shorter exposures (faster shutter speeds) though there is a trade-off as faster film also produces grainier pictures.
Digital cameras of course, do not use film & instead feature electronically-controlled ISO equivalents. Once again, a trade-off exists between ISO & the Signal to Noise Ratio (S/N)* of the digital sensor.
Film speed is usually the first & easiest decision when taking a photo. Unless you are looking for a grainy picture or there is poor light, it is wise to use the slowest standard film or lowest digital ISO available. Even where there is some shade or overcast conditions, compensation for slow film can be made by way of shutter speed. Nonetheless, high ISOs are not always avoidable & of course, do present a useful tool where a flash is either not available, cannot be used or is just unwanted because of the tendency to produce two dimensional exposures. If you want to photograph your night-flowering Cereus for example, fast film & a tripod will prove your best friends. The thing to most remember is that this option is available when it's needed & can be played with in conjunction other variables.
*S/N is the balance between light that comes from the subject (signal) & that which does not (noise). As the ISO equivalent is increased on a digital camera, the trade-off between signal & noise will become visible as discoloured pixels; normally by ISO 800.
A thistle at ƒ/4.8.
A fungus at ƒ/3.2.
In simple terms, an aperture is a hole of adjustable diameter that is used to control the angle of light flowing through a lens. The angle of light-rays meeting at a camera's image plane defines Depth of Field (DoF). Reducing aperture also reduces the volume of light reaching the film or digital sensor, requiring the exposure to be balanced by way of shutter speed.
Aperture size is expressed as a Focal Ratio or ƒ/Number, which is its diameter relative to the focal length of the lens. Aperture ranges are often included in lens specifications, the smaller ƒ/N being the larger aperture. The maximum aperture is called Lens Speed.
The DoF defined by an aperture setting is the point at which the lens focuses along the image plane. Whilst taking a close up for example, it is better to open or increase the aperture so that objects immediately behind the subject will be blurred out. Because more aperture means a lower ƒ/N as the focal point moves toward the camera, good close ups are usually taken between ƒ/2.8 & around ƒ/4.8. More panoramic shots of course, are taken at a lower aperture or higher ƒ/N.
Aperture is normally the second variable to decide when taking a photograph. As with film speed, a pre-determining factor is available light. Another is the size & situation of the subject. The better illuminated the subject, the wider the range of apertures available at high shutter & low film speeds. When the subject is large or distant, the focal point should move away from the camera, resulting in slower, more distantly focused exposures. Under low-light conditions, small apertures will require fast film &/or the use of tripods as shutter speed is reduced. This can all seem rather mathematical & confusing at first, especially since increasing aperture means applying less of it in real terms. Fortunately, there are simple guides that can be followed.
The ƒ-number ƒ/# - often notated as N - is given by ...
where ƒ is the focal length & D is diameter. By convention, ƒ/# is treated as a single symbol & specific values of ƒ/# are written by replacing the number sign with a value. For example, if the focal length is 16 times the diameter, the ƒ-number is ƒ/16 or N = 16. The greater the ƒ-number, the less light per unit area reaches the image plane of the system.
A Golden Orb Weaver at ƒ/2.8
On a sunny day, an aperture of ƒ/16 & a shutter speed close to the ISO inversed, will result in a generally balanced exposure. For example, an aperture of ƒ/16, ISO 100 & a shutter speed of 1/100 meets what is called the Sunny 16 Rule. This rule is approximate as all lenses - particularly zoom models - absorb light in themselves. The thing to remember is that light reflecting from nearer objects are captured more distinctly the more apertures are opened. Lowering aperture in order to focus on distant objects equates to squinting our eyes to see the horizon. In these shots, foreground objects will blur as the camera looks past them.
Whilst DOF increases with ƒ-number, aperture also affects image quality; depending on the lens or more particularly, the materials used in its manufacture. The sharpest images are found between ƒ/5.6 & ƒ/8 in standard, modern lenses. In older lenses, ƒ11 gives the sharpest pictures. The aperture of the human eye incidently, varies approximately from ƒ/8.3in bright light to ƒ/2.1 in darkness.
A Blue Gum at ƒ/8.0.
Shutter speed is the most variable & usually last setting decided before a photograph is taken. Naturally, the function depends on time which affects exposure quite differently to aperture. This is because of motion. Shutter speed is measured in seconds of exposure time. High shutter speeds freeze moving subjects, whilst slower speeds allow movements to blur. In sports & other types of action photography, both high & low shutter speeds are used to interesting effect. This can be no less the case in the garden or the wild, where movements abound.
Given good light, a fast shutter can capture a rain splash, falling leaf or an insect in flight. A slow shutter may convey the movement of wind through trees or the depth & colour of a night garden. Just as importantly, it acts as the final, balancing variable when film speed & aperture are already determined.
Shutter speed calibrations are standardised 2:1 like aperture F-stops, so that opening aperture & increasing shutter speed by equal stops, will result in consistent exposures.
A wasp rests on a swaying leaf.
Standard Shutter Stops
Stillness of the camera becomes a consideration at low shutter speeds. For handheld shots, a rule of thumb is that the lowest safe shutter speed is inversely closest to the lens focal length. For example, the lowest safe speed for a 35mm camera with a 50mm lens, is 1/60 s. For slower shots, a tripod would be necessary.
A grasp of the theory is a handy thing to have but of course, it is not the same as experience. Knowing how an aperture works for example, is not the same of knowing which dial controls the one in your camera. Additionally, there are other situational considerations such composition, direction of light & care of the camera itself.
Preparing your camera
The very first step to taking a photograph is ensuring your camera is clean & functional. For this, you will need a soft, static-free cloth & a cleaning fluid, usually alcohol-based. These are handy to have in the field, meaning a camera case or bag is really a must as well. A big no , no is using tissue paper which contains wood fibres or your clothes as these will carry grit & detergent products. Not only do such materials run a risk of scratching the glass in parts like lenses & viewers, but also the special chromatic & water-repellant coatings that often come with them.
It is also important to know your camera. Taking time to read the manual & learning to recognise the icons & controls featured, is a very good idea. The more you become acquainted with your camera, the more you will get from it. This is especially true of modern digital cameras which normally feature a broad range of features such as in-built flashes, various exposure modes (sepia, black & white, macro et al.), 2 in 1 photographs, automatic tracking, infra-red pre-flashes & more. Even some older cameras have automatic configurations in-built for night-time, moving subjects & other situations. Whilst it is not adviseable to form a habit of relying on these, they can be handy guides when learning to master your camera in various contexts.
Other practical considerations include making sure batteries are charged, sufficient film or memory is available & useful accessories like tripods, filters & light-meters are not left behind. Many a photographer - including the writer - has spent time setting up the perfect shot, only to discover the camera has no power or no film.
Assessing the situation
The purpose of the photograph is the foremost consideration when planning your shot. You may wish to capture colour, texture, atmosphere, perspective, contrast, movement or any combination of these things. The options available will depend upon level & direction of light, so it can important to make the best of the situation by shooting from a particular direction or distance, at a given aperture or shutter speed or merely, during a certain time of day.
Shot at dawn.
Subject off-centre leaving background undivided.
Early morning, late afternoon & when sunlight is diffused by cloud cover, are generally good times to take photographs. This is because diffused lighting avoids problematic contrasts between direct light & shadow. Filtered or diffused lighting allows you to photograph a subject from any angle & at a good range of apertures & shutter speeds. Even under ideal conditions, it is a good habit to use a tripod if one is available or take advantage of any situational platform that will safely support the camera. Free hands not only leave a steadier camera, but also allow you to move things like branches & so on that may be in the way of a shot or cast unwanted shadow. If you have a remote shutter-release, it is a wise practice to use it as often as possible.
Despite good planning, direct light is not always avoidable. In such circumstances, it becomes important to consider the direction of lighting. Shooting into the sun will place the subject in its own shadow. In such circumstances, a common technique is balancing the shot on the subject & leaving the background over-exposed. When standing between the subject & the sun, the photographer must be aware of the shadow he or she projects. Crouching & standing at angle to the subject from the sun, are good practices in such situations.
Composing the shot
Rather than centering on an object, good photographers tend to emphasis contrast between foreground & background; either of which will contain the subject. This is because the human eye sees in this way. Placing a subject in the middle of a picture divides the background, robbing it of potential secondary interest. A rule called the Golden Mean or Rule of Thirds amongst other names, divides a photograph into nine parts, placing subject away from center. Whilst this rule is elastic, the principle is worth observing in many cases.
As outlined previously, shutter speed is normally the final variable to determine when taking a photograph. Antique cameras sometimes have light-meters in-built that require ISO (ASA) & aperture to be dialled in. The resultant shutter speed is then set before exposure. A handheld light-meter is used in essentially the same way & can be handy for testing the light around a situation quickly. Modern digital cameras will invariably feature an electronic light-meter known as an AE or Automatic Exposure. This is a microchip that calculates what it believes to be a balanced exposure based on ISO, aperture & available light. Its visual interface is called an Automatic Exposure Lock or AEL, which acts basically as an old fashioned light-meter with the advantage of automated shutter speed adjustment.
A dog's life
There is no doubting the handiness of an AEL but they are not something that should be slavishly obeyed. Since digital exposures can be viewed immediately, it is possible & adviseable to use your AEL as a guide, adjusting shutter speed as shots are taken. It is important also, to be aware of what light an AE is "seeing" & not base exposure time on the sun for example, when photographing a subject in shadow. In circumstances where direct sunlight is unavoidable, it is a good idea to point the camera away from the sun, balance the AEL & then return to the shot. The resulting photograph will feature over-exposure, but not of the subject. This technique - like employing DoF - is a natural & effective means of defining subject in a difficult context. In other words, the human eye is no more able to look into the sun than it is able to focus on near & distant objects simultaneously.
Given manual control of the camera & an understanding of the principles, you can apply rules & bend them in order to develop your own style. High key photography for example, concentrates on lighter tones, commonly featuring deliberate over-exposure. Often used to convey feminity or atmospheric brilliance, it is a technique suited to subjects such as flowers. Low key techniques on the other hand, concentrate on dark & moody tones, producing stark & effective winter exposures. Artifical light sources - even a household lamp - can be introduced to wash out backgrounds such as in the direct sunlight technique or to produce directional light. Light striking a subject from different angles will highlight various aspects such as surface contours or the shape of objects; which can be very useful in illustrative photography.
The most important things are to enjoy taking photographs & to remain unafraid to experiment. Given time to master technique & style, a photographer can gain great satisfaction from the ability to express oneself through a camera. Good photo work allows you to show the world as you see it & turn even the most personal experiences into something others will enjoy as art. A picture as they say, paints a thousand words.
Find Out More:
- A good list of camera icons - PhotoNotes.org.
- Another list of purely digital icons.
- Collection of photo composition articles - PhotoInf.com.
- Rules of photo composition - excellent article on Colorpilot.com.
- GimpShop - the best freeware photo editor available.