Shooting with prime lenses

Most cameras come with zoom lenses and many photographers are happy to stick with a zoom any time they take photos. After all, zoom lenses are versatile – it’s convenient to have a range of focal lengths in a single lens so you don’t need to change lenses.

But sometimes a prime (single focal length) lens is the only option. Prime lenses also have some advantages zooms can’t provide.

In the past, many people thought prime lenses were for only professional photographers but in recent times they have become much more affordable with major camera manufacturers and specialist companies like Tamron, Sigma and Tokina vastly increasing the options available.

Across the most popular range of sensor sizes, prime lenses can be found in focal lengths ranging from extreme wide-angle (including ‘fish-eye) to extreme telephoto.

Prices vary widely across this range, depending mainly on the amount of glass required. The fastest, heaviest lenses are the most expensive.

In this feature we’ll look at the benefits of prime lenses and report on situations in which they can give you better pictures. We also provide tips on how to make the most of their advantages.

Only option

In some situations, a prime lens is the only option available. Macro lenses are a case in point, principally because designing a lens that can focus with ‘life size’ magnification (or greater) is less complicated when you don’t have to allow for zooming.

The term ‘macro’ is often erroneously used interchangeably for ‘close-up’, although the terms are not synonymous. By definition, a true macro lens must provide a reproduction ratio of 1:1. Lenses that can’t do this are not true macro lenses.

Macro lenses are the only ones that will provide ‘life size’ magnification at close distances. But they also capture a very shallow depth of focus even when stopped down a little, as shown in this example, which was shot at f/4.5 with a 50mm macro lens. 

Macro lenses must be designed to: eliminate aberrations; focus colours more accurately; and provide maximum sharpness on close-up subjects across a wide range of aperture settings. Most are also corrected for flat fieldwork, such as photographing stamps and coins. To meet these requirements, macro lenses are generally slower, bulkier and more costly than non-macro lenses of equal focal length.

Macro lenses come in different focal lengths, depending on the size of the camera sensor for which they have been designed and the uses to which they will be put. The table below shows some typical macro lens focal lengths and working distances for common sensor sizes.

‘Full frame’ 36 x 24 mm	‘APS-C’ 23.5 x 15.7 mm	Micro Four Thirds 17.3 x 13.0 mm	Typical working distance
	28mm	30mm	9.3-10.5cm
	30mm		12cm
50mm	35mm		13-16cm
	40mm		14cm
60mm		45mm	15cm
		60mm	19cm
	60mm		16-23cm
	80mm		27cm
90mm	90mm		28-30cm
100mm	100mm	100mm	30-32cm
105mm			30cm
150mm			38cm
180mm			47cm

Regardless of the size of the sensor, longer focal lengths provide greater working distances with 1:1 magnification, although the sensor’s crop factor will influence the effective focal length(s) available. Longer working distances make it less likely that live subjects will be disturbed by your proximity. They also minimise the chance you will cast a shadow over the subject.

Preferred option
Prime lenses will be a preferred option for photographers specialising in portraiture or landscape/architectural photography. There are a couple of reasons for this choice.

Firstly, prime lenses are likely to be faster than zooms, which means they allow more control over depth of field in shots. Most zoom lenses with a focal length range between 24mm and 70mm on a 35mm camera have maximum apertures of between f/2.8 and f/4.5.

In contrast, 24mm (equivalent) prime lenses are available with maximum apertures of f/1.2, f/1.4 and f/1.8. The same is true for 50mm primes and 85mm primes, the latter a favourite of portrait photographers.

A fast 24mm lens made it easy to frame and capture this landscape shot with a ‘full frame’ DSLR camera a little after the sun had set. (Shooting data: ISO 200, 1/20 second at f/11.)

Wide maximum apertures will provide a brighter viewfinder image in the optical viewfinder on a DSLR camera, making it easier to frame shots in dim lighting. Mirrorless cameras with electronic viewfinders (EVF) don’t share this advantage but their EVFs are less noise-affected and refresh faster when more light reaches the sensor.

Wide apertures also translate to good separation of the subject(s) from the background in portraits. They also tend to produce more attractive bokeh (rendition of out-of-focus backgrounds), another desirable characteristic in a portrait lens.

The maximum aperture of f/1.8 with a 105mm lens on a ‘full frame’ DSLR camera provided good separation between the subjects and the background, along with a smooth and attractive bokeh.

Prime lenses will also enable landscape and architectural photographers to shoot with extended depth of field. Even though zoom lenses can be stopped down to f/16 or smaller apertures, their performance usually deteriorates from about f/8 due to the effects of diffraction.

In contrast, a good prime lens will offer consistently superior performance across a wider range of apertures than a zoom lens. This means photographers looking for greater depth of field can stop down to f/13 (or smaller) apertures and be confident the quality of the resulting image will not suffer unduly.

Prime lenses have a couple of other advantages over zooms. Because their optical designs are simpler, they have fewer moving parts. This tends to make them more robust. Depending on the amount of glass used, they may also be lighter than zoom lenses that cover similar focal lengths. Depending on the speed (maximum aperture size) of the lens, they may also be cheaper to buy.

Photographers who settle upon one or two prime lenses will find they soon become familiar with the ‘look’ and ‘feel’ of each lens. They learn how the lens ‘frames’ a scene and become able to visualise the crop before raising the camera to the eye. They know almost instinctively where to stand and what shooting angle to adopt to get the result they want.

Regardless of whether you shoot with a prime or a zoom, settling on just one lens means no more lens changing (an advantage that applies equally to using a single zoom lens). This will result in no more dust on the sensor and, maybe, you won’t  even require a camera bag. The main disadvantage of choosing a prime lens is you may need to move more (see below) when composing shots.

Shooting with prime lenses

One argument in favour of prime lenses is that they stimulate a photographer’s creativity. Zoom lenses can make some photographers lazy because they can encompass a variety of shot compositions by staying in one place and simply zooming in and out.

The rule when using a prime lens is to ‘zoom with your feet’. Be prepared to move towards or away from your subject until it is framed as you want it. This, alone, is often enough to make you pay more attention to shot composition – and, as a result, obtain better, more interesting shots.

Suppose you can’t move back far enough to fit the subject inside the frame? Simply rotate the camera to the vertical (portrait) position and capture a series of panorama shots that encompass the subject. It’s easy to stitch them together with editing software.

A wide-angle lens with no rectilinear distortion will meet the needs of architectural photographers who specialise in interior shots.

Although faster lenses are also good for avoiding camera shake and freezing the action in low light because of their greater light-gathering capabilities, they can present problems if you want to shoot with a wide aperture in very bright conditions. In such cases, investing in a neutral density filter will allow you to reduce the light entering the camera to provide more flexibility with aperture settings. This can let you shoot wide-open without over-exposing the shots.

Choosing the right lens

As mentioned, macro lenses should be chosen on the basis of the subjects you’re shooting and the working distance they provide. But what about lenses for other applications?

Landscape photographers usually opt for wide-angle lenses to encompass the wide perspectives they normally photograph. Working distance is relatively unimportant and, unless they plan to shoot in low light, the ‘speed’ (maximum aperture) of the lens is largely irrelevant since most shots will be taken at f/8 or smaller apertures to maximise depth of field.

Architectural photographers will have similar requirements to which they will add a need for lenses with little or no rectilinear distortion and vignetting. When shots are taken with the camera tripod-mounted, the need for lens speed is minimal, although it becomes important when the photographer shoots with the camera hand-held.

An example of a hand-held shot taken with a 35mm equivalent lens. (Shooting data: ISO 200, 1/20 second at f/1.2.)

Portrait photographers are in a different category. Their needs change whether they are taking  head-and-shoulder shots or photographing groups of people.

Head-and-shoulder photographers tend to settle upon short telephoto lenses, with focal lengths from about 75mm to 135mm (35mm equivalents). Such lenses impart a slight compression of perspective that is flattering to the human face. Lens speed is useful but very fast lenses must be used with care to ensure the focus is upon the subject’s nearest eye and the plane of focus is wide enough to encompass much of the rest of the face without making the background too sharp.

Wider lenses with focal lengths of 28mm or 35mm are ideal for larger groups of people or when shooting in tight indoor spaces. Take care when shooting with wider angles of view because even a slight tilt of the lens with respect to the subject can produce unflattering distortions.

The 50mm focal length has been a favourite of street photographers ever since the first 35mm cameras appeared just over 100 years ago. They are also popular with some portrait photographers because their perspective is similar to human vision.

The 35mm equivalent focal length is favoured by many street photographers because it enables them to include some background to provide context to shots but is small and light enough to be easily carried and relatively inconspicuous.

Many street photographers prefer a slightly wider angle of view and here, the 35mm focal length comes to the fore. These lenses are normally slightly more compact than 50mm lenses, which makes them less conspicuous.

Choosing between a 50mm and a 35mm lens for street photography is largely a matter of the photographer’s personal style and the working distance they prefer. Those who are comfortable shooting close to subjects and those who like to include some background to add context to the subject will favour the wider lens. Narrower lenses can provide more creative options with depth of field and smoother bokeh.

Extreme telephoto lenses are favoured by sports and wildlife photographers primarily because they provide the only way to get close-up shots of otherwise impossible-to-photograph subjects. Expect to pay a premium price for fast lenses, which will also be relatively heavy because of the glass they contain.

Article by Margaret Brown – see Margaret’s photography pocket guides  

Excerpt from  Photo Review Issue 77   

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