Studio flash systems are more powerful than the flashguns built into cameras and even the external dedicated flashguns made by the camera maker. They don’t offer the same level of automation as built-in or dedicated flashguns, though, so they do require a basic understanding of exposure and lighting ratios.
This is not really a big disadvantage and, in fact, it can be a lot easier to set up the lighting manually than it is to try to unravel the various auto modes and overrides of dedicated flash units.
Studio flash consists of the flash unit itself, which is usually mains-powered but battery power is sometimes available. The flash unit is mounted on a stand and the lighting is controlled with a range of accessories including softboxes, brollies and more.
It’s possible to work with just one light and a reflector (for bouncing light back into the shadowed side of the subject), with two lights (the second light can be used as a ‘fill light’) or with three. The third light may be used to light the background separately, or to provide a ‘hair light’ for portrait shots.
The power of each flash (the ‘flash’ or ‘lighting’ ratio) can be adjusted independently to produce the desired lighting balance and attachments can be used to adjust the quality of the light for each one. Flash units usually incorporate a ‘modelling lamp’ which will give an indication of how the lighting will work, though the power is much lower than the flash itself.
In any multi-flash setup you have a ‘master’ flash connected to the camera, usually via an ‘x-sync’ cable although wireless flash units are also available. The ’slave’ flashes may be fired wirelessly the master flash but in studio systems it’s more common for optical ’slave’ sensors to be used instead. These detect the main flash and instantaneously fire the ’slave’ flash.
It is possible to calculate flash settings and arrive at the correct exposure by trial and error, but the best and quickest results will be achieved with a ‘flash meter’. An ordinary ‘ambient’ light meter won’t be able to cope with the brief duration of the flash.
You can buy the components for a studio flash setup individually or save money by getting everything you need as a kit.
Flash works by discharging an intense but brief burst of light. The duration of the flash is very short, typically around 1/1000sec. This has an effect on exposure because the shutter speed no longer has much, if any, impact on the brightness of the image. In fact, the shutter’s job is simply to be open at the right time.
The Canon EOS 400D was one of the best-selling digital SLRs of all time, and with good reason. It combined a compact but robust design with an excellent control layout and, for the time, cutting edge resolution. It’s now been replaced by the EOS 450D, which boasts 12 million pixels rather than 10, a bigger LCD, slightly faster continuous shooting (3.5fps instead of 3fps) and a live view mode. 
Ricoh’s GR compact film camera was a surprise cult hit. It had a fixed focal length 28mm which limited its scope and, unlike a zoom, made you work to get your pictures. But photographers loved it because it did a simple job brilliantly, excelling for travel and street photography and as a camera to keep in your pocket for ‘grab’ shots when an SLR would be too slow or awkward. The GR Digital II is the second incarnation of its digital replacement and it’s just as single-minded. In a market dominated by high-zoom, high-gloss consumer gadgets, it’s a brave return to a simpler, more direct style of photography. 
The D60 is Nikon’s cheapest digital SLR and it’s clearly designed with novices in mind. Nikon hasn’t stinted on features, though. The 10-megapixel sensor is perfectly adequate and delivers sharp, rich images, and the kit lens is a VR (Vibration Reduction) version of Nikon’s usual 18-55mm zoom. It’s small, neat and easy to use, but while the user interface is clear and supremely logical, changing common settings does take quite a few button-presses. 
Canon’s EOS 1Ds has long been regarded as the king of all professional digital SLRs. For a long time it was the only camera with a full-frame sensor, until it was joined by the cheaper EOS 5D. The current version, the 1Ds MkIII, has a 21-megapixel CMOS sensor and its twin-DIGIC III processors can capture those huge image files at a creditable 5fps. But the 1Ds MkIII no longer has everything its own way. The 24-megapixel full-frame Sony a900 is one-third the asking price, and Nikon’s full-frame D3 is around half the price. The 1Ds MkIII will also be drastically undercut by Canon’s new EOS 5D MkII, also with a full-frame sensor, also with 21 million pixels. 
The Nikon D3 is currently (November 2008) Nikon’s flagship professional SLR. Nikon caused a stir when it introduced this camera, its first full-frame model. It superseded the DX-format D2x and, suddenly, Canon did not have a monopoly on full-frame photography. However, the D3 has ‘only’ 12 million pixels, where the EOS 1Ds MkIII has 21 million. For the time being at least, the Canon has a numerical advantage. The question is, of course, whether you really need 21 million pixels, and whether the D3 has other qualities to make up for it. 
Nikon now makes two ranges of SLRs: lower-cost DX-format cameras which use APS-C sized sensors and professional FX format SLRs which have full-frame sensors. The D300 is the top-of-the range DX format model. It has professional build quality and features and it’s an ideal choice for those who’ve already invested heavily in DX lenses. 
When it first came out, the Sony a700 was a big step forward for mid-range digital SLRs, and for Sony’s own camera range. Cheaper Sonys were based on the old Konica Minolta Dynax 5D body, but this is more like the weightier Dynax 7D. Its aimed at a much more serious group of photographers, with a higher-resolution 12-megapixel CMOS sensor, twin control rings and a 5fps continuous shooting speed. The chassis is aluminium and the controls are sealed against dust and moisture, and the 3-inch LCD has 921,000 pixels for extra clarity. 
Sigma’s SD-series D-SLRs look expensive for their resolution, and they use a revolutionary multi-layer sensor that’s yet to achieve mainstream acceptance. So is the SD14 an overpriced white elephant or an early glimpse into the future? And what about the new SD15? The resolution of the new camera will be unchanged, though there’s a bigger LCD and upgraded image processing. The hot news right now, by the way, is that Sigma has just bought out its sensor manufacturer, Foveon.