Digital Camera Fundamentals
When comparing the specifications of digital cameras, it can get a little confusing if you are not well versed in the terminology used. As you go through this section, be sure to refer to our Glossary as necessary for clear explanations of terms. In this article, we explain the most important attributes of a digital camera and what they can offer you.
WHAT TYPE OF PHOTOGRAPHER ARE YOU?
There are basically four categories a photographer can fall into: Point-and-Shoot (P&S), Beginner, Serious and Advanced.
As a P&S photographer, you buy a camera to take snapshots of family and friends. You want your digital camera to be as easy to use as possible, with minimum fussing over controls, hence the term “point and shoot.” Most digital cameras are therefore P&S types. They provide AUTO shooting mode (with its many variations), and perhaps also Programmed Auto (also referred to as Programmed AE), as well as Scene Modes.
But when your interest in photography grows and you start asking pointed questions about how you can take a certain type of picture, or create a certain mood, a P&S digital camera, even with all the available shooting modes, will usually not provide enough exposure flexibility for your needs. A beginner photographer needs a digital camera that allows control over all the exposure settings. Besides the shooting modes found on most P&S cameras, cameras geared for beginner photographers will also provide Aperture-Priority shooting mode, Shutter-Priority shooting mode, and full Manual shooting mode. It is becoming almost impossible to find affordable digital cameras that have these semi-auto and manual features now.
Serious and advanced photographers also desire full control over their digital cameras. But much more than that, having used a camera for many years, they are more cognizant of what features are important to them and having those features readily accessible as dedicated buttons is an important consideration. How the camera feels in their hands, the availability of accessories and, of course, improved image quality and performance are all factors that come into play when they choose their next digital camera.
P&S Shooting Modes
In AUTO shooting mode, the camera makes practically all the exposure decision for you.
In Programmed AE shooting mode, the camera still makes most of the decisions, but allows you to specify certain exposure parameters, such as ISO, White Balance and which the flash mode to use. You can leave everything as default and then Programmed AE is the same as AUTO mode.
Scene Modes automate some of the more challenging shooting situations where AUTO and Programmed AE modes will give you a correct exposure but the picture still does not seem right because the camera got “fooled” by the particular lighting in these situations. Some examples are sunsets (shooting into the sun), bright snow scenes (surrounding is too bright), shots by candlelight (surrounding is too dim), night portraits (near subject is too dim, far background is too dim), etc. In each of these situations, an experienced photographer would know how to manually adjust exposure settings so as to capture the picture the way our eyes see it. Scene Modes attempt to incorporate this expertise and make it available to the inexperienced photographer: just tell the camera which scene you are shooting and leave it to the camera to make the appropriate exposure adjustments.
Other features popular on P&S digital cameras are Face Detection (where the camera automatically detects the faces in a scene and focuses on one of them), automatic Red-Eye reduction (red-eye occurs when the light from the flash is reflected from the back of the eye), shadow brightening, and noise reduction.
Advanced Shooting Modes
In Aperture-Priority shooting mode, you tell the camera which aperture to use and the camera then selects the appropriate shutter speed to obtain a correctly exposed picture. Typically, you would use a large aperture to get a shallow depth of field and obtain blurred backgrounds — perfect for portraits. You use a small aperture to increase depth of field and obtain a picture that is sharp from foreground to background — perfect for landscapes.
In Shutter-Priority shooting mode, you tell the camera which shutter speed to use and the camera then selects the appropriate aperture to obtain a correctly exposed picture. Typically you would use a fast shutter speed to “freeze” action, such as in sports photography. You use a slow shutter speed to “suggest” motion in your pictures due to the blurriness that results when a fast moving subject is photographed with a slow shutter speed. The quintissential example is photographing flowing water: a slow shutter speed captures the fast moving water as a cloud.
In full Manual shooting mode, the photographer has full control over all the settings of the camera. This provides the most exposure flexibility and allows for creative photography. Note that some P&S digital cameras lists “Manual” as one of their shooting modes, but it is only a limited Manual mode, more akin to Programmed AE.
Compact Digicams vs DSLRs
Compact digicams are P&S cameras with many “smart” features. These digital cameras have come a long way, with the capability to focus on a face (even recognize a face), take a picture only when the subject smiles, recognize the scene in front of you and select a scene mode automatically, smooth out the subject’s face (and presumably also the wrinkles and other “imperfections”) when taking a portrait, etc. Though most advanced photographers rank these features as “gimmicks,” they are not bad to have if you don’t want to learn how to do them manually and in post processing.
The two important features every consumer should consider before buying a digital camera are: image quality and performance. Can the camera take good pictures, especially in everyday low light situations? Is the camera responsive so you do not miss the shot? Once you are satisfied these two criteria have been met to your satisfaction, only then should you consider the smart features.
Beginner and serious photographers want full control over their digital cameras. Digital cameras geared for serious photographers are similar to those for beginner photographers, except that they provide better image quality, more parameters you can have control over, faster and more precise auto focus, faster continuous shooting, better performance, availability of add-on lenses and filters, possibility to use a more powerful external flash, more buttons and external controls for quicker operation (instead of having to search in the MENU), etc. They can also have more complexity than a beginner just learning about cameras would want. But, as stated earlier, cameras geared for beginners (i.e. with manual features but at an affordable price) are becoming very rare.
Advanced photographers typically graduate to a digital SLR (DSLR) camera which provides the ultimate in exposure control and flexibility. Performance is near instantaneous, image quality is excellent, and the lens is interchangeable, which means you have access to a specialized lens for almost any type of photography you may wish to pursue. Accessories also abound. Note that though entry-level and Family DSLRs may not provide the same high image quality or performance that is traditionally associated with DSLRs targeted to serious and advanced photographers, they still provide a level of image quality and performance that is much better than could be obtained from a consumer non-DSLR digital camera.
The newest generation of DSLRs are not DSLRs at all. DSLR stands for Digital Single Lens Reflex with the “Reflex” part referring to the mirror inside a DSLR. The mirror is needed to redirect the light coming through the lens up into the viewfinder. Today, with the availability of high resolution display screens, the use of a mirror, pentaprism/pentamirror and viewfinder is obsolete. The new Digital Interchangeable Lens camera (DIL) substitutes the mirror with a high resolution display screen and the optical viewfinder with a high resolution electronic viewfinder. Not only does it see exactly what comes through the lens (as a DSLR does), it also goes a step further and shows the photographer what exactly will record on the image sensor! These DIL cameras are also more compact and lighter than the traditional DSLR.
How many megapixels resolution should your digital camera be able to capture? Pixels are the dots that together make up your image. So, in theory, the more pixels a digital camera has, the more detailed an image it can capture. More pixels also allow the advanced photographer to crop the original image in an image editing software for the most appropriate composition.
However, in practice, there is a limit as to how many pixels can be crammed onto a tiny image sensor before image quality deteriorates. It seems that 7MP or 8MP allows the best image quality in the tiny sensors used in most compact digicams. Higher megapixels resolution simply results in more noise. Aggressive noise reduction then takes place in-camera resulting in images that have lost fine detail, thus negating the reason for using more megapixels in the first place.
Another consideration to take into account is the amount of compression used to save an image. The effective megapixels resolution of a digital camera is the number of pixels it uses to capture an image. In general, the more megapixels, the more detailed the image that is captured. However, the captured image is then saved, usually as a JPEG file which is compressed. Most digital cameras allow you to specify the amount of compression to use: the less the compression, the more detailed the image saved, but the bigger the file; the more the compression, the less detailed the image saved, but the smaller the file. However, many beginner cameras do not give you that option and save the image with a lot of compression. So, even if a digital camera is advertised as 12MP, the truth of the matter is that it may save its final image with so much compression that most of the detail it captured in the original image ends up being thrown away. So, shopping for a compact digicam based on megapixels alone is often a losing proposition.
How much storage media is enough? Some beginners wonder why people get so hung up with large storage media when we previously could at most capture 36 exposures on film? The truth is that we were of course never satisfied with 36 exposures and carried extra rolls of film in our pockets. Pros would even attach a film back to their film SLR that would give them hundreds of exposures.
I like to use the highest capacity and fastest memory card available for my camera. If it’s new, the price can be prohibitive, so wait a couple of months for the price to become more reasonable. There is really no point in carrying lots of memory cards with small capacity. Usually one high capacity memory card is enough and I just leave it in the camera, downloading pictures when I’m done shooting and reformatting the card in-camera for the next shooting session.
You also want to shoot at the highest resolution at all times, which means that you need all the storage space you can get. Shooting at the highest resolution ensures you capture an image at the highest resolution and with the best image quality your camera allows. [Why else did you buy that camera?]
Advanced photographers go a step further and save their images in the RAW file format (where minimum to no processing is performed in camera), which requires much more memory space than a regular JPEG does but gives the maximum flexibility in bringing out the best image quality possible from the images in post processing. A high capacity memory card is essential here.
Why should you care what the maximum aperture is? Simple, the maximum aperture decides how much light your camera lets in to record the picture. The larger it is, the more light gets in, thus allowing you to shoot in a bigger range of lighting situations. With a large enough aperture, you could shoot on a cloudy day or indoors without the use of flash; you could shoot action pictures using a fast shutter speed; you could shoot portraits and throw the background out of focus.
If the maximum aperture is small to start out with, you can only shoot in a limited range of lighting situations, and would be overly relying on the flash to provide enough light to properly expose your shots. More often than not, the on-board camera flash is pretty weak and useful mainly as fill-in flash. You would be using slow shutter speeds which means that action shots without flash would be impossible. Slow shutter speeds also mean that any movement on your part (i.e. camera shake) may result in blurred pictures.
Some digital cameras have a limited aperture range. Instead of an iris that opens (larger aperture, more light gets in and less depth of field) and closes (smaller aperture, less light gets in and more depth of field) in increments, they might have only 2 preset aperture settings. In fact, some might not have an iris at all, which means that you cannot really control depth of field. The aperture might be “electronically controlled” by moving a filter into the light path to cut off the amount of light reaching the image sensor; this, in effect, simulates a smaller aperture setting but depth of field is not affected. Technically, 2 preset apertures with no ability to control depth of field is a limiting factor for those who want to explore digital photography.
OPTICAL VS. DIGITAL ZOOM
Optical zoom uses the optics of the camera to bring your subject closer, just like in a conventional non-digital camera.
Digital zoom simulates real [optical] zoom and is just another fancy term to mean “crop and enlarge” a portion of the actual picture, which always results in a loss of image quality.
When comparing digital cameras, always use optical zoom, not digital zoom. And ensure that any digital camera you purchase either allows you to disable digital zoom entirely or warns you clearly that it is switching to digital zoom. “Seamless” optical to digital zoom, without an appropriate warning, might sound good in the marketing literature but is definitely not a good idea.
SHUTTER SPEED RANGE
Your camera relies on the combination of aperture and shutter speed to determine proper exposure. If you have a wide range of shutter speeds, you have more latitude in deciding what aperture to use and what kind of pictures you can take. If you have a limited range of shutter speeds, or worse only three or four shutter speeds, you might find that most of your shots are underexposed, or the camera applies software techniques to “boost” the available light by manipulating the image captured, which usually results in loss of image quality. So, even though you might buy a high resolution digital camera, its limited shutter speed range may effectively diminish its ability to captue high quality images. Bottom line: ensure that your digital camera provides a full range of shutter speeds ranging all the way from fast (e.g. 1/1,000 sec.) to slow (1 sec. and more).
A Note on Shutter Speed/Aperture/ISO
To properly expose a picture, your camera needs to let in enough light to reach the image sensor. So, let’s assume we set a fixed aperture (the opening of the iris in the lens that allows light in).
In a sunny situation, there’s lots of light, so a camera set on Auto mode will usually select a fast shutter speed (say, 1/125 sec. or 1/500 sec.) so the image sensor is exposed for only a short time to the light.
In a cloudy or dark situation, the camera on Auto mode will usually select a slow shutter speed (say, 1/30 sec. or 1/15 sec.) so as to allow the image sensor to be exposed for a longer time.
Basically that’s how shutter speed works for a selected aperture. Usually, however, the camera on Auto mode will select different combinations of shutter speed and aperture to obtain proper exposure.
In general, the following applies: a small aperture means less light reaches the image sensor, so the camera needs to open the shutter for a long time; a large aperture lets in more light, so the camera can select a fast shutter speed and so the shutter stays opens for only a short time.
You can also set the image sensor sensitivity (ISO) to “affect exposure” (technically incorrect, but good enough conceptually). A high ISO needs less light, a low ISO needs more light for proper exposure. A common problem with current consumer digital cameras is that high ISOs introduce quite a bit of noise as to be mostly unusable, so don’t get fooled by features on paper. Even though a digital camera is advertised as having a high ISO capability it does not necessarily mean the high ISO is practically usable.
WHITE BALANCE (WB)
The image sensor in a digital camera does not “see” light the same way that film does. The sensor just receives light, generates an analog charge that must then be interpreted by software to digital pixels. This gives digital cameras the ability to adjust color in camera. White Balance allows a digital camera to calibrate all the colors based on the color White. In finding a reference White, all other colors are adjusted accordingly. Ensure that your digital camera allows you to select different WB settings for different lighting situations, such as outdoors, cloudy, fluorescent, and tungsten. The better digital cameras allow you to manually calibrate the white balance (Custom or Manual WB) using a white (or gray) card.
Most consumer digital cameras today feature Scene Modes. Scene modes are simply preset exposure/shutter speed combinations (together with white balance and exposure compensation) to account for most of the common picture-taking situations, such as portraits, indoor fluorescent lighting, landscape, and night scene. Scene modes, if properly implemented by the camera manufacturer, save you from having to fidget around with the aperture, shutter speed, white balance and exposure compensation to obtain proper exposure.
A note of caution is in order when talking about scene modes. The fact that a digital camera offers a particular scene mode does not necessarily mean that you will be able to capture good images with that scene mode. Let me elaborate in more detail, with the following examples:
Let’s say a digital camera offers a Sports or Action scene mode. You might think that this means you will be able to capture great action shots with this digital camera, right? That’s what the salesperson would like you to believe. The answer is, Maybe. It all depends on what the digital camera offers technically.
To understand this completely, let’s review what are the necessary technical requirements for being able to successfully freeze a fast indoors action shot: 1) a fast shutter speed (say, 1/1,000 sec.); 2) a wide aperture (say, F1.8); 3) a powerful flash; 4) ISO of 800 and above; 5) white balance for fluorescent and tungsten lighting; 6) a small shutter lag (you’ll never catch the action if the shutter clicks 2 sec. after you press the shutter release).
Let’s assume your digital camera offers a shutter speed of 1/1,000 sec. — fast enough to stop action. It has a maximum aperture of F2.8 — OK for outdoors action shots in bright sunlight, OK for indoors action shots using a powerful enough flash, but not “fast” enough for indoors action shots where flash is not permitted. In the latter case, you’ve got no recourse but to increase the film equivalent sensitivity to ISO 800 or above. Now, there are not too many digital cameras, except for the very expensive digital SLR cameras, that deal well with the increase in noise level at the higher ISOs. So, the Sports or Action scene mode on this digital camera is, for all practical purposes, useless to you if indoors action shots without flash is what you’re after. It has the Sports scene mode but it can’t really take such pictures.
Similarly, Night Scene mode is really useful if a digital camera provides a shutter speed of 1 sec. and slower. But if the slowest shutter speed is 1/4 sec., ummm… not much is possible as far as night pictures are concerned even though the camera offers Night Scene mode. Most Night Scene Modes go down to 4 seconds and permit some night photography.
Another scene mode may be Auto ISO where the camera selects from a wide range of ISOs (say, ISO 100, 200, 400, 800, and 1600) to allow you to capture indoors low-light shots without using flash. It sounds good on paper, but consider that if you find that the noise level at ISO 200 and higher is unacceptable usng this camera, then, for all practical purposes, the higher ISOs that are available are useless (unless a ‘noisy’ picture is the ‘image effect’ you’re after).
So, when comparing digital cameras, do not blindly rely on the features on paper — it pays to read expert reviews and actual owners’ opinions to ensure that a particular feature that is offered is actually usable in practice.
To properly expose a picture, your camera has to measure how much light is available. Multiple Pattern is the most common type of metering used in today’s digital cameras. Also known as Matrix Metering, it takes light measurement from various areas of the framed shot and then uses a database of scenes to match the current scene and set the correct exposure.
Centre Weighted-Average (CWA) metering takes one measurement, giving extra weight to the centre of the frame.
Spot Metering takes its light measurement only from a small central spot of the screen.
Different cameras have different light metering schemes, but they are mostly variants of the three basic ones above.
Which light metering mode should you use? Multiple Pattern will be fine for most situations. However, you are relying on the camera (and the completeness of its scene database and the accuracy of its matching algorithms) to determine which part of the scene is most important. If you care for one part to be accurately exposed, then use Spot metering on that spot. Many pros who like to set the exposure manually rely on CWA metering instead of Multiple Pattern metering for consistent results. This is because Multiple Pattern metering can give different exposures if you move even a little bit, resulting in a different “scene.”
PANORAMA VS. WIDE-ANGLE
An interesting development with digital cameras is the “panorama” feature which allows you to take a number of regular shots and digitally “stitch” them together in an image editing software (or in-camera) to produce a panorama picture. This is a great development and panorama pictures can be breathtaking to view. It is very impressive when used to take a wide landscape vista or a large group of people, say a club’s members or a large family with grandparents and grandchildren, all lined up. Depending on the software used to stitch the frames together, your panorama pictures can come out looking great or the seams where the frames have been stitched could be visible and result in a not so good picture.
A lens with a good wide-angle coverage (say, 24 mm) will allow you to include more of the picture in the same one frame. To contrast, a panorama picture needs many frames to cover the same angle of view. In other words, I can capture all the glory of a breathtaking view with a wide-angle lens and display it on my PC monitor. With panorama pictures, the same coverage will be bigger than your PC monitor and you’ll have to scroll left and right to view the image. To view the whole panorama image on one screen, you need to shrink it to fit.
One is not better than the other. Both can give great images. It is desirable to have a camera with a wide-angle lens. You can still take panorama pictures and because a wide-angle lens covers a wider field of view, you will require even less frames for a wider — and more breathtaking — panorama.
There are many more things to learn about your camera and photography. Join us in our Digital Photography Tutorials section.
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