Digital camera lenses explained
Digital camera lenses come in a variety of focal lengths, with various technologies and capabilities making their price vary from one to the next. We explain all you need to know about digital camera lenses to ensure you buy the right one.
Digital camera lenses explained
Once you’ve settled on a new camera, the next temptation comes from the lenses which will accompany it. Prices of digital camera lenses vary from the affordable to the eye-watering, and often it can be difficult to see why – so it’s important to know what you’re getting for your money.
The lens which will typically come with a new camera will suffice for everyday photography, but a new optic can quite literally broaden the scope of your picture taking. Newer digital camera lenses are specifically designed for modern DSLRs, and as such help prevent unwanted side-effects such as internal reflections from ruining your images, but older optics equally have their charms, particularly simply-constructed prime lenses which can often last a photographic lifetime.
Whatever digital camera lens it is you need to elevate your photography to the next level, you should remember a few important points:
Digital camera lenses explained: Focal length
Firstly, most DSLRs have an APS-C sized sensor, whose dimensions are smaller than the traditional 35mm size of a frame of film. This means the effective focal length of whatever lens you use changes; to find out the effective focal length for your camera/lens combination, find this figure in your camera’s specifications list (typically 1.5-1.7x) and multiply it by the focal length of your lens. So, for example, a 50mm digital camera lens on a body with a 1.5x crop-factor sensor will result in an effective focal length of 75mm, while a 28-70mm lens will effectively be a 42-105mm optic.
Digital camera lenses explained: Compatability
Second, although a digital camera lens may be available in the right mount for your camera, it may not be fully compatible – again, your camera’s manual will explain which lenses can and cannot be used.
Many newer lenses are designed specifically for cameras with APS-C sensors, which means that they either cannot be used on full-frame cameras, or can only be used with limitations. It is even possible to damage your camera by using the wrong lens, so don’t leave this to chance.
Digital camera lenses explained: Requirements
Finally, think about what kind of photography you practice, as this will determine which lens you should be looking for. ‘Fast’ digital camera lenses, whose aperture is fixed at around f/1.4 or f/1.8 let in a lot of light and allow shallow depth of field, attributes which lend themselves well to indoor photography and portraiture respectively.
The same kinds of digital camera lenses with smaller maximum apertures, such as f/3.5 or f/4 tend to be cheaper, but will suffice if you only ever take landscapes, for example, where the likelihood is that you will be requiring smaller apertures to maintain sufficient depth of field.
Digital camera lenses explained: Types of lenses
Wideangle zoom lens
A wideangle digital camera lens typically covers a focal range from around 12-24mm or 16-35mm, and allows you to fit landscape scenes, architecture or anything else where you need a wide angle of view.
Some suffer from a little barrel distortion at wider settings, where the image takes on a slightly barrelled appearance, but this is only likely to be objectionable when shooting close up to your subject, or when the scene has defined linear details. It’s advisable to use a lens hood with such lenses (which are often supplied) to prevent unwanted light from entering the frame which can cause flare and a drop in contrast.
The standard digital camera lens offers a focal length of around 50mm, which translates to around 75mm on many DSLRs. As such, a 50mm camera lens lends itself perfectly to portraiture, particularly as such lenses often offer wide maximum apertures to create shallow depth of field.
Thankfully, despite being classed as ‘fast’ lenses, their simple construction makes then an inexpensive and lightweight addition to your kit bag.
Superzoom digital camera lenses are a popular choice for keeping on your camera, as they span a wide focal range, from wideangle right through to telephoto. Typically this will begin at around 28mm and culminate at close to 270 or 300mm.
Many contain image stabilisation to help at longer focal lengths, though the maximum aperture available can be restrictive in order to achieve such an expansive focal range.
Although they are less suited for specific types of photography, they are ideal for travel photography where both flexibility and portability are key considerations.
Telephoto zoom lens
A telephoto digital camera lens gets you closer to the action, and so is ideal for sports and wildlife where you may need to keep your distance. These can either been prime or zoom lenses, and usually cover a focal range of between 100mm to 400mm.
Their construction makes them costly, and only the most expensive lenses can offer relatively wide apertures of around f/2.8. Even so, for any kind of action photography, where you need to maintain fast shutter speeds, there’s no real alternative.
Macro lenses can focus closer to your subject than a conventional lens allows, which allow you to capture plenty of intricate details.
Commonly used in nature photography, but well suited for portraiture too, macro lenses typically offer wide maximum apertures for shallow depth of field, and are renowned for their high optical qualities.
Other specialist lenses
Fisheye lenses offer an exceptionally wide angle of view but are purposefully distorted to create the ‘fisheye’ effect. They come in two different varieties: full-frame and circular, which respectively capture an image to fill the whole frame and a circular image contained within the frame.
Although they are commonly used for landscape photography, they can be fun to use within other genres, such as in portraiture and architecture.
Tilt-and-shift lenses, meanwhile, are used most commonly to correct for the effects of converging verticals in architectural photography, but their control over depth of field makes them ideal for any kind of photography where the plane of focus needs to be altered. In other words, the photographer can use these to vary depth of field without having to change the aperture.
They can also be used to make subjects appear as though they are miniatures, although their price restricts them to those who need to use them on a professional level.
Get help choosing the right lens by reading the What Digital Camera lens reviews
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