This article was written by Andrew S Gibson, the author of Understanding Lenses: Part II, and is part of a series of lessons about camera lenses. Links to the others are at the bottom of the article.
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Before zoom lenses became the norm most cameras came with a 50mm lens as standard. Since then, the humble 50mm prime has fallen somewhat out of favour. Which is a shame, because 50mm prime lenses can give you high quality and versatility at a low price point. On an APS-C camera it’s one of my favourite focal lengths. Let’s take a look at why.

50mm prime lens vs. kit lens

If you own a kit lens or zoom that covers the 50mm focal length you may be wondering why you would buy a 50mm prime. After all, you already have that focal length covered. The answer is that 50mm lenses have some advantages that kit lenses don’t:

Better image quality

50mm lenses are simple beasts from a design point of view. Lens designers figured out a long time ago how to make a good quality 50mm lens, and the result is that the optical performance of even the least expensive 50mm prime outshines many zooms.
I used a Canon EF 50mm f1.8 II lens (Canon’s cheapest) on a full-frame camera to take the photo below, my first time using it for photographing architecture, and I was amazed at the detail it captured when I enlarged it to 100%.
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Price

50mm lenses are simple. They tend to have six to eight elements inside – zoom lenses may have more than double that. That means manufacturing costs are lower. It is likely that the cheapest lens in your camera manufacturer’s range is a 50mm prime. Most 50mm lenses represent excellent value for money.
However, when making a purchase (of any lens, not just a 50mm) it is wise bear in mind that more expensive models of the same lens have better build quality, autofocus performance, weatherproofing and maybe a wider maximum aperture.
Canon, for example, has three 50mm prime lenses (plus a 50mm macro lens) in its current range. You may not notice much difference in image quality between the 50mm f1.8 II and 50mm f1.2L – but you will notice the difference in build quality and autofocus performance. I opted for the middle option and bought the mid-range 50mm f1.4.

Wide maximum apertures

For me this is the most exciting aspect of 50mm primes (indeed, any prime lens). If you have a kit lens the long end (around 55mm) has an aperture of f5.6 or thereabouts. A prime 50mm lens has an aperture of f1.8 or wider. That’s over three stops. It makes a difference when shooting in low light as you can open up the lens rather than increasing ISO. It also helps you take photos with shallow depth-of-field.
This photo was taken at f1.8 with a 50mm lens:
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Getting the best out of a 50mm prime lens

Once you have a 50mm prime lens the next step is learning to get the best out of it. These are the things that I use my 50mm lens for:

Walk-around lens

A 50mm lens is a nice walk-around lens to take on a day out. I took these photos with my 50mm f1.4 lens in China. On a full-frame camera it’s a convenient focal length for this very casual style of photography. On an APS-C camera it will help you close in on interesting details.
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Portraits

On an APS-C camera a 50mm prime lens effectively becomes a short telephoto lens, ideal for portraits. It works well on a full-frame camera as well, as long as you don’t mind a little distortion. The photos below show a couple of portraits taken with an 85mm lens.
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Close-up photography

You can use a close-up lens or extension tubes with a 50mm lens to take close-up photos. You can also reverse mount it onto another lens to take macro photos (the techniques are covered in detail in the linked articles). This greatly increases the versatility of the lens. If you already own a 50mm lens these are cheaper options than buying a macro lens.
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Previous articles

These are the previous articles in the series:

Understanding Lenses: Part II

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If you liked this article then take a look at my latest eBook, Understanding Lenses: Part II – A guide to Canon normal and telephoto lenses. If you hurry, you’ll get a discount – scroll down for details.