Canon EOS 1100D announced

The 1100D replaces the 1000D, Canon's basic starter SLR. It adds a slightly higher resolution 12-megapixel sensor and standard HD (not full HD movies).


There's a revised version of the 18-55mm kit lens too. The new Feature Guide pitches this camera straight at beginners, and it looks like a cautious upgrade designed not to undermine the more expensive cameras in the range.

• Launched: February 2008
• Type: Digital SLR
• Sensor: APS-C 22.2 x 14.7mm
• Resolution: 12.2 megapixels
• Lenses: Canon EF-S, EF
• Key features: Standard HD movies, Feature Guide
• Links: Press release, Product page

Canon EOS 600D, Canon's top amateur SLR

The 1600D replaces the 550D as Canon's top amateur/beginners SLR. On the surface, it's not much different to the 550D, offering the same sensor size and resolution, but adding a Feature Guide for novices and an articulating display. It's a step-down from the EOS 60D and EOS 7D, which have sturdier metal construction and faster continuous shooting.

• Launched: February 2008
• Type: Digital SLR
• Sensor: APS-C 22.3 x 14.9mm
• Resolution: 18.0 megapixels
• Lenses: Canon EF-S, EF
• Key features: Full HD movies, Feature Guide, articulating LCD
• Links: Press release, Product page

Dual card slots

Many digital SLRs aimed at keen amateurs and professionals have two memory card slots, and this is not just to increase the overall storage capacity.

Then can be used for this, of course, but high-capacity memory cards are cheap these days, and storage space isn't the problem it was.

Some cameras use dual slots to offer support for two different card formats. This Nikon D-SLR can take both SD cards and Compact Flash.

Instead, you can use the two card slots to store different types of data which you want to keep separate. Depending on whether the camera supports it, you could do the following:

• Save photos to both cards at the same time so that you always have a backup in case one memory card fails or gets lost

• Use one to store RAW files and the other to store JPEGs (for cameras which offer simultaneous RAW/JPEG shooting)

• Use one card to save photos and the other to save movies

Shutter life

This is one indication of a digital SLR's durability, and it's measured as the number of exposures, or 'cycles' the shutter is designed to be able to withstand during its life. (You don't usually see this figure quoted for other camera types.)

Makers won't usually bother quoting a figure for basic or beginner-orientated cameras, but shutter life is often used as a selling point for more advanced or professional models.

A few years back, 100,000 cycles was regarded as the standard for professional cameras, but this has crept up and Nikon, for example, now quotes 150,000 cycles for its D7000 model, while its high-speed D3s pro SLR has a shutter rated at 300,000 cycles.

This sounds a lot, but it's not a warranty of any kind, just an indication of how long the designers expect the shutter mechanism to last - and it may go on much longer than that.

Amateur photographers are unlikely to wear out their cameras' shutters before the camera itself becomes obsolete and is replaced. If you do carry out any back-of-the-envelope calculations with your camera's shutter life, do remember that for every picture you save, you might take many more which you discard, and they all count towards the total shutter life.

Continuous shooting

This is where the camera keeps on taking pictures in rapid succession while you hold down the shutter button. This can be an important feature for sports, wildlife and any kind of action photography.

All digital cameras allow continuous shooting, but there are big differences in (a) how fast they can shoot, and (b) how many shots they can take before they have to stop and save them to the memory card.

The continuous shooting speed is called the 'frame rate' and is quoted in 'frames per second', or 'fps' for short. Many compact cameras struggle to shoot more than a couple of frames per second, but digital SLRs and hybrid cameras can shoot faster.

How fast do you need?
• 3fps is about as low as you'd want to go. It's adequate for fairly slow-moving subjects, but it's easy to miss the key moments between frames.

• 5-7fps is a lot more useful for sports and action, and you've got a better chance of capturing crucial moments.

• 8-10fps is the sort of speed achieved by professional SLRs designed for sports, action and press photography. At this speed you can be pretty sure of capturing the perfect moment.

• 30fps+ speeds are achieved by a few high-speed compact cameras, notably Casio's high-speed continuous-shutter cameras. Even digital SLRs can't match these speeds, but because these high-speed cameras use smaller sensors and can't sustain these speeds for long, they don't offer either the quality or the capacity needed by most professionals.

How many shots you can take?
At some point the camera will have to pause to process and save all the frames you've shot, though some cameras can shoot JPEGs indefinitely, up to the capacity of the memory card.

How many shots you can take will depend on the camera's processing power, the size of its images (megapixels), the size of its internal 'buffer' (short-term memory), and whether you're shooting JPEG or RAW files. You can save many more JPEGs than RAW files because the files are smaller.

Some compact cameras can shoot at high speeds too, but you may find the capacity is limited. Fujifilm's FinePix F550EXR, for example, can shoot 8 frames a second, but only for 8 frames.

Zoom range

A lens's zoom range is the ratio between its minimum and maximum focal lengths. So a 28-84mm lens, for example, has a zoom range of 3x, because its magnification at 84mm is 3x its magnification at 28mm.

Zoom range is an important selling point, especially for compact cameras, where the average buyer may have difficulty working out the lens's range from its focal lengths alone.

Superzoom cameras like the Canon PowerShot SX30 IS have the largest zoom range of all. This camera has a 30x optical zoom, and the diagram below shows the huge difference in scale between the wideangle end of the zoom range (the tiny figure on the left) and telephoto end (the large figure on the right).

It can be misleading, though, if you start to assume that the bigger the number  the better the lens. One problem is that the zoom range doesn't tell you the lens's widest angle of view, which is very important. Being able to magnify distant subjects is all very well, but in everyday photography a wideangle lens is more useful for 'getting everything in'.

It is important, then, to check the focal lengths anyway. A 5x zoom with a focal range of 24-100mm equivalent is likely to prove a lot more useful in everyday use than a 10x zoom with a focal range of 35-350mm, because a lot of the time the 35mm minimum focal length just won't prove 'wide' enough.

The other problem is that zooms with a very long range don't always perform that well, particularly at their maximum zoom, where pictures can often come out quite soft-looking and low in contrast. This can happen even if the camera uses a very high shutter speed, demonstrating that it's the lens that's the problem, not camera shake or user error.

The performance of superzoom cameras can often be quite disappointing for this reason, and this applies to pretty well all lenses with an extra-long zoom range. They're more versatile than normal lenses, but the quality is usually compromised to some degree.

Maximum aperture

The maximum aperture of a lens represents its light-gathering ability, and it's an important selling point. The smaller the number, the wider (or 'faster') the lens aperture.

This is the scale of aperture values. These are whole 'f-stops', but there are apertures in between ('half stops' or 'one-third stops'):

• f1 (very rare)
• f1.4 (some fixed focal length lenses)
• f2 (some zooms)
• f2.8
• f4 (most standard zooms start at f3.5, which is mid-way between f2.8 and f4
• f5.6 (the maximum aperture of most standard zooms at their maximum focal length*)
• f8
• f11
• f16
• f22

* Zoom lenses rarely offer the same maximum aperture throughout their zoom range, which is why the lens specs will quote something like 'Nikkor 18-55mm f3.5-5.6'. That means the maximum aperture at 18mm is f3.5, but at 55mm it drops to f5.6.

Each aperture value in the list above is one stop (or 1EV) 'faster' than the one below it. F1.4 is two stops 'faster' than f2.8, which means you can use an ISO setting two stops lower or a shutter speed two stops faster.

There are zoom lenses with constant maximum apertures, but these are much bigger, heavier and more expensive.

Fixed focal length lenses like this Nikon 50mm f1.4 have wider maximum apertures because their optical design is simpler and the designers can push the envelope in different directions.