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Digital cameras are significantly more expensive than film cameras and require considerable time and skill to produce quality prints. So why are they leaping off delighted retailers’ shelves? Part 1: By Kevin Poulter The Electro T here are three main reasons for the sales success of digital cameras: one of the most intensive marketing campaigns in history, peer pressure to be up to date and yes, digital has some advantages over film. The major advantages? (1) No film or processing costs; (2) Ability to preview the results immediately for a quality check; (3) Automatic white balance; (4) Immediate results – view and transmit images via the Internet or as prints, in minutes; (5) No waiting to complete a roll of film; and (6) Easy to carry, compact size. The rationale of these articles is to cover technical information generally not in camera magazines, without replacing the 200-page manual supplied with prosumer cameras. Without film and processing costs, digital photography is effectively free, so it’s a breeze to take more images. This invariably leads to more choices, enabling amateurs to produce better images, plus professionals save time and know how their images will look. There are industrial and business advantages too, like incredibly detailed, lower power x-rays – safer, more informative and quicker than conventional technology. Results are easily viewed, stored and transmitted, with computer 8  Silicon Chip Digital x-rays (right) need less power than conventional (left) and exhibit much more detail. In this case, the dark area seen in the digital x-ray is very important. The very light area of filling is not a problem, as the software has brightness and contrast controls. siliconchip.com.au onic Camera controls like brightness, cropping and sharpness. Automatic white balance is a brilliant exclusive-to-digital feature. Of all the advantages, the immediacy leads as the standout attraction. Some of the digital advantages can also have their own disadvantages: (1) No film/processing cost for images means the photographer usually takes many more shots of the same thing. (2) Previewing the results immediately for a quality check takes time. (3) Considerable computer time and “grunt”, plus quite detailed knowledge of image processing software, is needed to achieve the best images. Aren’t the first two points the same as the advantages? Yes, but with a sting! Professional and amateur photographers can produce thousands of images, so vast hard drive space is needed, requiring more investment in computer hardware and possibly software. This leads to very expensive repercussions, which will be highlighted in the second part of this series. Digital cameras are more aptly titled ‘electronic cameras’, siliconchip.com.au as nearly every component and innovation is electronic. From the first image capture to outputting as prints, digital photography relies on a flow of electrons. Even the zoom and ‘manual’ focus in lenses is often achieved via motors within the lens. Compared to film counterparts, digital cameras have undergone exponential development since their introduction just a decade ago. Digital photography’s evolution relied on new complementary technologies, requiring rapid upgrading of emerging technology – such as the personal computer, memory cards, batteries, image sensors and infrastructure, even enlarging booths. Improvements in image resolution compared to digital camera prices have been nothing short of astounding. This is fuelled by demand, competition and the rise and rise of China as a source of cheap production. Quality digital cameras are now as low as a third of the price of comparable units just 12-18 months ago. Like their film predecessors, digital cameras come in one of three basic configurations: (1) Fixed lens, (2) fixed lens with zoom or (3) SLR (Single Lens Reflex) – interchangeable lens type. The camera you select depends on your March 2006  9 The Olympus E-300 with the optional twin battery compartment. Many cameras use proprietary batteries which cost many times “standard” cells. But you can’t make a mistake fitting them! camera’s on-board computer. Groups of four RGGB pixels are allocated an average value through interpolation of the values. Once the colour and other parameters of the image are established, the camera’s computer further processes the image to produce a sharp, contrasty, colourful photograph. This provides an enlargement that consumers like – most of the time. Sensor electron flow budget, enthusiasm and the camera magazines you read. Certainly SLRs offer the best quality, with wide zoom range, though fixed lens cameras are available with up to 12 times zoom, plus excellent portability. Digital zoom is a feature in most cameras too but not recommended, as it’s simply digital amplification or enlargement of portion of the image. Increased noise and loss of detail is unavoidable. Besides, you can enlarge a section of an image later in a computer, rather than in the camera. When selecting a digital camera, choose a leading brand like Canon, Olympus, or Nikon, with all the features you want and excellent software to suit your computer. In 2005, the digital SLR camera that accomplished the greatest price versus performance impact was the Olympus E-300. This was made possible by Olympus relocating their manufacturing to China, resulting in a Japanese quality camera at Chinese production prices. How does a digital camera work? Light from the subject is focused in the lens, captured on the sensor, digitally processed by an inbuilt computer for optimum colour, contrast, brightness, clarity and file size, then stored onto a card – all in a second or two. The storage on the card usually accounts for the lion’s share of that time. Firstly, the camera needs to know if there is a colour bias in the light. We 10  Silicon Chip have seen the orange illumination in candlelight or from an open fire but there are other strong colour casts we cannot see so easily, like the green tint in many fluorescent tubes. Digital cameras do a great job of neutralising these unwanted casts, by automatically adjusting to correct the colour temperature. The spectral balance of white light sources is rated numerically by colour temperature. With incandescent lighting, this corresponds roughly to the absolute lamp filament temperature, expressed on the Kelvin (°K) temperature scale. The higher the colour temperature, the more bluish tones while lower colour temperatures have increased reddish tones. Nearly all sensors are the CCD (Charge-Coupled Device) array of light-sensitive elements (often referred to as pixels, which stands for picture elements, the smallest discrete component of an image). Each is covered by an in-register set of filters, one for every element. The filters are red, green and blue, though there are twice as many green filters, as this makes digital images appear sharper, without significantly escalating noise. Light falls on the pixel, causing an electrical charge; the more light, the higher the charge. The charges are transferred down the line of pixels, then the camera reconstructs the electronic image, like painting by numbers. The RGB grid of pixels has digital signal processing applied by the If the RAW setting is used, the image is not boosted or processed at all. This sounds great for professional users but RAW creates very large files, requiring both large in-camera storage and considerable enhancement in a computer. A good compromise for top quality images is to change the camera’s settings to low colour, low contrast and low sharpness. The rationale is that these can be boosted later in the computer but if left at the rather high boost factory settings, it’s near impossible to reverse the effect of the excessive enhancement. Once the image data moves from the sensor and is processed digitally, Digital cameras have reliable auto white balance, with advanced models offering a manual adjustment for precise colour. siliconchip.com.au How the CCD works: light is seen by photodiode ‘pixels’, focussed through individual micro lenses, each with a colour filter. The vertical data transfer channel electron flow reaches the horizontal data transfer channel to exit the CCD. This jumble of electrons is then sorted to a viewable photograph, it’s directed to a buffer memory, then saved to a memory card. With advanced 35mm film cameras, a motor-drive captures action like sports and motor racing. The number of frames of film that can be shot is primarily limited to the speed of the motor-drive and its ability to position the next film frame quickly. Digital cameras don’t have motordrive delays but have an equivalent in the ‘burst-rate’. It is limited by the image processing delay plus latent writing time, both dependent on the file size and the internal memory buffer. To minimise these processing delays, the buffer memory temporarily stores images, allowing more images to be exposed in a continuous burst. If a digital camera is purchased for action photography, the burst rate at full resolution, lag (between pressing the shutter and exposure) and autofocus speed are vital factors. Some digital cameras are impotent when it comes to speed and this can be disastrous to discover after purchase! Many cheaper digitals take as much as a second or more between the time the shutter button is pressed and the time the image is actually “shot”. In candid photography, even half this is plenty of time for the subject to turn their head away or even for someone else to walk into the frame and block it! Burst mode is very useful for photographing in dim light too, as hand- held photography normally results in blurred images. Using the sequential (burst) setting, hold the camera very steady and take a burst of say, six images in rapid succession. Chances are one of the frames will be clear enough to use. Alternatively, in low light situations, place the camera on a tripod and set it to self-timer, just as you would have done with a film camera. This avoids blurring while pushing the shutter-release. The photograph of Above: three of the typical memory cards (there are several others) used in modern digital cameras – all three these days would be regarded as very small capacity (SanDisk, for example, now has a 4GB CompactFlash card available). At right is a table showing the typical file sizes for various qualities of digital image, at various compressions. RAW and uncompressed TIFF files don’t take long to fill even a large card. siliconchip.com.au March 2006  11 Choosing the Athlete mode for most general photography tells the camera to keep to the highest shutter speed possible. This avoids camera shake (blur) in all but the lowest light. the BMW interior (page 14) was taken using this technique. For most photography, the digital camera is best set on autofocus and the athlete symbol. The latter ensures the camera selects the highest shutter speed possible, avoiding camera shake. Lens focal length The overall size of the chip governs the lens’ focal length compared to 35mm film cameras. As many people are very familiar with the older film cameras, focal lengths of digital lenses are often quoted in sizes equivalent to 35mm. For example, a 14mm Olympus digital lens has the same angle of view or lens coverage as a 28mm lens in a 35mm film camera. The need for wider-angle lenses in digital also favorably affects the depth of field – the distance from the nearest to the furthest point of perceived “sharp” focus in a picture. Digital lenses therefore produce images with a greater focus depth and are less prone to camera-shake. Digital camera manufacturers prefer to make digital-specific lenses, rather than adapting 35mm lenses, as they require an optimum light path and must be higher resolution to maintain good clarity on the small sensor area. However, “film” lenses with the same mount and electronic connec- of viewfinder when too close to the subject. Advanced viewfinders show exactly what the camera sees. Through-thelens (TTL) systems display the image in the viewfinder via a prism, flip up mirror, image-splitting or combinations of these. TTL viewfinders can have a disadvantage – on slow shutter speeds or when the photographer is not shielding the viewfinder (like on self-timer), light may enter via the viewfinder, fogging and overexposing images. ‘Band-aid’ solutions supplied by manufacturers include a plastic piece to cover the eyepiece! The mirror viewfinder system has excellent brightness in the viewfinder and near perfect cropping of the intended image. The Olympus E-300 overcame the traditional large bulge at Some SLR cameras can have light enter via the viewfinder in low-light shooting. To avoid fogging, a simple piece of plastic is used to cover the viewfinder. EYECUP tions (eg, for autofocus, auto aperture, etc) can usually be used with a digital camera. Viewfinders & mirrors The viewfinder may be as simple as a hole in the camera body, with lenses to look through. Parallax (out of alignment) errors occur in this type EYEPIECE COVER the top of the viewfinder by designing a mirror that flips sideways. When SLR lenses are changed, there’s a real possibility of dust intrusion onto the mirror, or worse, the sensor. Olympus all but eliminated dust contamination by an ultrasonic cleaning burst every time the camera is switched on. This high tech solu- Left: photo before adjustment showing histogram levels settings. Right: improved Photo after levels adjustments. 12  Silicon Chip siliconchip.com.au Left: high resolution image. Centre: low resolution image (note loss of clarity and increased noise); and right: highly compressed JPEG (note compression artifacts) tion is mated with a low tech ‘bin’ for the dust – an adhesive strip below the sensor! The adhesive strip is replaced when the camera is serviced. With SLRs, it’s also possible to have dust land on the mirror or rear lens element. Both intrusions look enormous, as they are so large compared to the image. If you see a foreign body through the viewfinder and it’s not on the photographs or viewfinder, then the dust is on the mirror and easily blown away. A camera hurricane lens blower is very useful for dust, though if it comes with a hair brush, discard the brush, as it’s a dust collector and can also easily place grime onto the lens. Another TTL viewfinder utilises a micro LCD ‘monitor’ screen. Some reviewers protest it’s difficult to focus with this low-resolution system. Most photographers soon adapt, especially as autofocus is very accurate and the image is viewable in any light. With or without glasses, photographers’ vision varies greatly, so many viewfinders have a variable diopter wheel. This enables the user to adjust the viewfinder preset focus to suit their eyesight. A popular viewer is the LCD screen on the back of the camera, backlit by a fluorescent tube. This can be very difficult to see in sunlight or even bright daylight. To remedy this, some LCDs display a much brighter image but the highlights, shadow detail and contrast are not WYSIWYG (What You See Is What You Get), so it only has limited value. The digital camera shutter is electronic. As a consequence, the camera is so silent, photographers can switch on a simulated shutter noise on some models! This is not as absurd as it sounds, as it confirms a photograph has indeed been exposed, especially when image processing is slowing photography down. Many cameras have settings like sepia or black and white. Using these settings reduces your options, as colour images can always be converted in a computer. But if they are exposed as sepia, the colour cannot be recovered later. RGB vs CMYK Regardless, all digital camera images are exposed as RGB (Red, Green, Black), as used in television and computer screens. Magazines, leaflets, etc are printed in four colours – CMYK (Cyan = a mid blue), Magenta (deep pink), Yellow and blacK. Conversion from RGB to CMYK in an application such as Photoshop requires experience, as the auto conversion in many graphics applications is not perfect. Look at photographs in a number of digital camera magazines and you’ll soon see mauve skies – the most common conversion error. Image brightness range can be depicted as a histogram, or graph of the light levels from the deepest shadows, to the brightest highlights. These image characteristics are important for optimum contrast, plus highlight and shadow detail in prints and are adjustable in graphics applications like Photoshop or Photoshop Elements. While there are other applications offering the same (or similar) control, Photoshop has become the industry standard for image manipulation and adjustment so for simplicity we will refer to Photoshop throughout this article. The many colour adjustment controls in Photoshop can be used to restore old colour photographs too. In the 70s, processing labs introduced fast machines. Over 30 years later, we find the speedy processing of the Fast film processing in the 70s was not light-fast, so they often have a highly magenta (pink) cast now. Photoshop can restore these images. siliconchip.com.au March 2006  13 than film or digital cameras. Astounding shadow detail can be recovered in many digital photographs but overall, nothing is superior to proper exposure. Photographs taken in medium to high contrast situations like sunny days have whites and dark areas with no detail. This is incompatible with printing enlargements, leaflets and magazines, where a narrow contrast range with detail in the light and dark areas is mandatory. If there is no detail in the white areas, for example, the printing press will not lay down any ink at all and the image will appear blotchy, as if it hasn’t printed correctly. Therefore most commercial printers like to see a contrast range of around 10%-90% or even 15%-85%, where 0% is white and 100% is black. To avoid excessive, unprintable contrast, one or both of these remedies can be utilised: (1) set the camera to low contrast and/or (2) make a double or triple exposure with images from too light to too dark. The different exposures can be aligned on top of each other as layers in Photoshop and then the extreme exposures removed with the eraser. Storage A higher resolution or wider angle of view is achieved by overlapping a number of images. In this case, three were overlapped to fit the entire scene. era was not light-fast and nearly all the images are barely recognisable through an immense magenta (pink) cast. Computer graphics software can help recover the missing colour. In Photoshop, there are a number of other methods available to improve image colour and brightness, like ‘variations’ and ‘curves’ plus external add-ons, called ‘plug-ins’. A popular plug-in is onOne Intellihance (formerly Extensis). The image sensor output is rated according to the number of effective pixels in the image resolution. For example, 8MP is eight million pixels. This pixel density or resolution influences the clarity, ‘grain’ or degree of magnification possible before noise and artifacts are seen. Artifacts are groups of pixels or unwanted noise, only seen under extreme magnification. For static subjects, it’s possible to achieve much higher resolution than the camera delivers by overlapping two or three exposures. The image at left is three 20Mb sections, joined and overlapped to make a true 60 Mb image. The collage was especially needed, as even the widest lens would not fit the scene in. The downside? For perfect results, enormous computer time is needed to match the sections, as optical distortion ensures they never fit together perfectly. A tip: when copying flat objects or documents to A4 size, don’t forget a flatbed scanner still has a higher resolution 14  Silicon Chip Image storage cards vary with camera brands. Popular types include CompactFlash (CF), SmartMedia/MMC, MemoryStick, etc. They are completely solid-state and are usually very reliable. There are also MicroDrives, which usually offer significantly more storage but have microscopic moving parts and are sensitive to magnetic fields, so they can be less reliable – but follow a few precautions and they rarely have problems. Cameras and memory systems are not infallible, so error messages are possible. If a memory card cannot be read, remedies are: (1) Turn off the camera and remove the card. Check for dust and fingerprints. Try again. (2) Put fresh batteries in the camera. (3) Try the card in another camera, at a photo lab or in a card reader. (4) Reformat (not erase) the card. This will wipe all images but most times saves a reoccurrence of the problem; or (5) Send the card to a data recovery specialist – the most expensive option. For image recovery software – see the article at www. aaa1.biz/sc.html The best insurance is to frequently save images you cannot Cameras and printing processes often cannot handle the range of density, from white to black detail, so taking three different exposures, from too light to too dark, then merging the best exposures in Photoshop results in a printable image. siliconchip.com.au afford to lose onto a computer and leading brand CDs – preferably more than one CD, if the images are vital. Digital cameras (and especially their LCD monitors) are power-hungry, so batteries are a premium item. Startling developments have been made in battery capacity and camera power conservation. Rechargeable batteries are almost essential and should be rated at least 2,000mAh. If they are used and recharged regularly, they will last for years, at a cost of just cents per ‘film’. Photographers can take measures to help a set of batteries last all day: set the LCD image preview off, or to just a five second glimpse (you can always manually recall the image and look at it longer), plus auto revert to standby mode after just a few minutes. Batteries can be very expensive, so consider aftermarket batteries from SILICON CHIP advertisers. But that’s not always possible: the Olympus E-300 SLR, for example, has a unique-shape 7.2 V lithium ion battery with a 1,500 mAh capacity, so owners are forced to spend about $200 for a battery that has a capacity similar to a set of AA rechargeables selling for less than $30! The plus side is their ease of use due to the keyway shape, enabling batteries to be loaded in even the lowest light. A number of sets of reliable rechargeable batteries and a regular recharging routine ensures you are always ready to take digital photographs. If you’re travelling and taking a notebook computer with you to download to, consider using a charger which plugs into the USB port, saving taking the camera charger with you. An alternative to taking the notebook is one of the self-contained mini hard drive/card readers, designed specifically for saving lots of images to. A tip: whenever you can, save the contents of any hard drive (notebook or self-contained) to CD/DVD (even multi copies), especially if the images are irreplaceable. While it’s now possible to take a set of images and deliver the card for processing, the ultimate is enhancing images yourself with creative work on a computer. If you are considering digital photography, factors include: Will it be better or more convenient than a film camera? Is the increased time needed to enhance in the computer taken into consideration? What resolution (megapixels) are needed to suit the enlargements that may be required? How fast is the camera – the lag time, shooting speed and delays for writing? Is the extra price vs. convenience worth it? What about the future? Nikon announced recently that it is ceasing most film camera and associated lens production; other manufacturers have/will follow suit. On the flipside, Konica-Minolta has announced that it is pulling out of digital camera market altogether after suffering huge losses. Some experts are tipping that 35mm film as we know it will be all but unobtainable in just ten years; not to mention processing availability. Digital cameras are a revolution embraced by many, but film/processing is still an option – for now! References and further reading: www.aaa1.biz/sc.html NEXT MONTH: We’ll look at some of the hardware required and some of the traps for young players . . . siliconchip.com.au March 2006  15