Zoom or Prime – an intro to focal length (and why you should care about it)

One of the questions I get asked most is what camera and what lens to buy. I don’t like telling people what they should or shouldn’t get because equipment choices are BIG decisions with a lot of pros and cons to weigh. I think that a lot of people get tripped up with all of the options. They don’t know what the different lenses are good for and they don’t know which ones they need. I can’t tell you what lenses you need. Only you can decide that. What I can do is try to give you a little bit of insight into what the differences are between lenses and help you try to understand which ones you might like best.

So lets start at the beginning. There are two main kinds of lenses. Prime lenses (also known as fixed focal length lenses) and zoom lenses. Your camera kit lens was probably a zoom and probably had a range of somewhere around 18-55. That’s pretty standard. A focal length of around 50mm is said to be the most similar to the way that our eyes perceive the world. Anything from 21mm-35mm is commonly known as “wide angle”, anything from 35mm-70mm is said to be “normal”, and from 70-135 is “telephoto”. A lot of kit lenses try to give you everything in one lens, all the way from wide angle to telephoto. The drawback to these lenses is often that they suffer in their aperture capabilities, opening even less when you are zoomed in (remember I said that your kit lens probably doesn’t go any wider than 3.5, well if you zoom in to its longest focal length that number will probably change to 5.6!) They make lenses that zoom and have wide apertures but those are usually very expensive AND very big, bulky and heavy. Take Canon’s f2.8 24-70 lens. That bad boy is over $1000! It is easier to make lenses with wider apertures that are fixed or prime lenses, so you can usually find those with much more reasonable price tags. The trick is you might end up needing a whole camera bag full of lenses to add up to one zoom lens and there went your savings.

So which is the “right way” to shoot? Zoom or prime? It’s one of the most commonly debated topics in photography and you will find people on either side fiercely defending their position. But which do I use? Primes if you must know. One of the little “bonuses” of prime lenses is that they often give you just a little bit more sharpness and open up just a little wider than your zoom lens. I also prefer to “zoom with my feet” moving closer and further from my subject to get the look that I want.

One of the common misconceptions among new photographers about zoom lenses is that the point of them is that you don’t have to get closer to your subject to make it bigger in the frame. What these new photographers are failing to realize is that the focal length has a HUGE impact on the look of your image. To help illustrate this point here are 3 images of my son. All taken with his head filling approximately the same proportion of the image.

The first image was shot with a 24mm lens. See how animated it is? The wide angle shows tons of the background plus makes the play mat look fun and exciting and very 3 dimensional. I love photographing babies with wide angle lenses because of the sense of whimsy they lend to the shots.

photography lessons on Permanent Riot by Katy Regnier photography

Next up is the 50mm lens. I was further from the subject (to get him to fill the same amount of the frame) and you can see that the image has started to flatten out a bit.

photography lessons on Permanent Riot by Katy Regnier photography

Here it is again, this time with an 85mm lens. Telephoto lenses compress space, making everything appear closer together and flatter. See how much closer he appears to the china cabinet in the background compared to the first shot?

photography lessons on Permanent Riot by Katy Regnier photography

Just to give you an idea of the change in distance between me and my son during this series, here is the 24mm lens again at the same distance as the 85mm shot.

photography lessons on Permanent Riot by Katy Regnier photography

Each of these lenses has their place. You obviously couldn’t get close up shots of your kid’s soccer game with a wide angle lens, and you probably wouldn’t want to photograph your mother with one at a close range either (wide angles tend to exaggerate features, making people look “cartoonish”). There is no catch-all one perfect lens. It’s important to realize the difference that the focal length is going to have on your final image. If you are using a zoom lens it’s easy to fall into the trap of using your zoom to determine how much of the frame the subject is going to fill. I could have stood in one spot and taken both of the last two shots without even switching my lens. But what I would have missed by doing so is the fun and whimsical nature of the first shot, something I could only achieve by moving MYSELF closer and not by zooming. Take a second to play with your lenses (whether they be zoom or prime) and really notice the effect that a different lens has on the mood of your images. Only once you’ve really started to notice those differences can you start to decide which ones best fit your style.

Zoom or Prime – an intro to focal length (and why you should care about it)

5 thoughts on “Zoom or Prime – an intro to focal length (and why you should care about it)

  1. Sara says:

    This one is very timely . . . I think I’m going to ask for a new lens for my birthday. Thanks for all of the great posts!!

    Sara (beefsbride)


  2. Wow, it’s a lot to take in, but I really appreciate all of the time you are spending on trying to explain all of this to us amateurs! Thank you….even though I’m still overwhelmed….but I am really enjoying reading and learning and hoping to take that next step!

    Marie (WinterBuckeye)


  3. maydaygirl says:

    I just bought a F/2.8 18-50mm lens and am loving the lower f.stop! I can’t wait to get my hands on a fixed lens though… one thing at a time 🙂

    Thanks for spending so much time and effort on this!


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