7 Commonly Asked Questions About Prime Lenses

By Caroline Schmidt. Posted

1. Do I need a big telephoto prime for wildlife or sports? Will a zoom not do?
With telephoto primes such as 300mm and 400mm f/2.8 or 500mm and 600mm f/4 costing anywhere up to £12,500, you’re right to question buying one! Fast maximum aperture telephoto primes tend to be the reserve of professionals who want the ultimate in speed and image quality. For beginners or enthusiasts, a versatile telephoto zoom, for example a 150-600mm, might not be quite as fast, or pin-sharp, but they come close for the price difference.

2. Why does a fast maximum aperture matter if I’m stopping the aperture down?
Firstly, most lenses tend to get sharper as you stop down, so a f/1.8 lens at f/4 will most likely be sharper than an f/4 lens at f/4. Secondly, having to open up wider can help in certain situations, such as low light. Finally, fast lenses work well with teleconverters – for example, attaching a 1.4x teleconverter loses you one stop of light, so that f/4 lens can now only open up to f/5.6, whereas an f/2.8 lens can open to f/4. A 2x TC loses you two stops of light, so your f/4 lens will now only open to f/8. This becomes an issue as many autofocus systems need a maximum available aperture of f/5.6 in order to autofocus, although some newer models can function at f/8.

3 I want a blurry background in my portraits – what lens should I get?
There are several factors that affect background blur – aperture, focal length, and camera/subject/background distance. The wider the aperture setting you use, the more shallow the depth-of-field and the more background blur. Longer focal lengths also appear to have less depth-of-field because they compress perspective, so an image shot at 200mm at f/2.8 will appear to have more background blur than an image shot at 50mm and f/2.8. Finally, the distance between the camera, subject and background plays a role – the closer to the camera and further from the background the subject is, the more background blur you’ll get.

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4. Am I able to use lenses designed for other brands on my camera?
Sometimes, and usually only with adaptors. For example, Canon lenses will fit many Sony cameras with an adaptor, and Nikon lenses can fit Canon cameras with an adaptor. However Canon and Sony lenses won’t work on Nikons because the Nikon mount is physically smaller.

5. Should I stick to lenses made by my camera manufacturer?
Not necessarily – third party manufacturers such as Sigma, Tamron, and Samyang all offer fantastic affordable prime lenses. Because primes are optically more simple than their zoom equivalents, it’s sometimes worth looking at even cheaper budget options. For example, Chinese brand Yongnuo now offer a 50mm f/1.8 lens for just £45!

6. What is a ‘nifty fifty’?
People refer to Canon’s original 50mm f/1.8 prime lens as the ‘nifty fifty’. Its small size, lightweight plastic housing and fast maximum aperture make it a great standard lens. It’s since been succeeded by the 50mm f/1.8 II and, more recently, the 50mm f/1.8 STM. The price is nice too, at around £120 new, or £75-ish second hand.

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7. What type of lenses is best for close-ups?
You’ll often find that a large number of dedicated macro lenses (that being, lenses that offer a true 1:1 reproduction ratio) are fixed focal length. The streamlined design of primes allows lens manufacturers to create macro primes with all the right characteristics, such as a short minimum focusing distance and high magnification. Many of the most popular macro lenses are in the region of 100mm or longer – longer primes are ideal as they offer a good working distance from your subject, whereas shorter primes might require you to get closer, potentially spooking off flighty subjects, or casting your own shadow over the subject that you’re photographing. Depth-of-field is inherently thin at high magnification, so a fast maximum aperture isn’t everything, however having the option of shooting wide open can create truly creative and compelling results. An added bonus is that longer macro primes tend to make for great portrait lenses too, as their focal length is considered flattering and they usually offer a fast maximum aperture.

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