Paul Timpa Photography Blog Photography Tutorials and Tips from Paul Timpa Photography


Choosing the best Focal Length for a photo

Tropical and Coastal Stock Photography - Images by Paul Timpa

Today's discussion revolves around focal length. While most of us are familiar with "zooming in" or selecting a longer lens to make our subject larger, or zooming out to "go wide" there is actually a more subtle, but in my opinion far more important effect of focal length, that should be thought about every time you take a photo and select a focal length or lens:

From a "photographic" perspective, it is focal length that determines how much distance appears between two objects that are at different distances from you (such as a flower in front of you and a mountain behind the flower). The actual distance between the two objects in "real life" is irrelevant and has no bearing on the photo. Through the "laws of optics" it is entirely up to you to set the distance between two objects, and you can set it however you like. That's why it's so important to recognize this every time you take a shot. Let's use a real life example to make it clearer:

Say you're in a field and there's a beautiful sunflower about 10 feet in front of you. Behind the sunflower, about a mile back, is a mountain. It is only to your eyes that the distance between the flower and the mountain appears to be a mile -- the camera can see that distance however it wants, longer or shorter, depending on how you set it. (FYI, if you put a 50mm lens on your camera (that's 50mm in 35mm's about 30mm in a non-full-frame D-SLR), that 50mm lens will cause the distance in the photo to appear about the same as your eyes (about a mile). That's why the 50mm lens is often called the "normal" lens -- because it sees distance the same as you would "normally" with your eyes. Now here's where things get creative -- any other lens besides 50mm will actually completely change the appearance of that distance between the flower and the mountain. The wider you "zoom out", the more the distance between the flower and the mountain is visibly "stretched". The more you "zoom in" the closer the distance between the two. The key here is that you must move your body by walking closer or farther to keep the flower the same size in the frame. For instance, if your starting position is 10 feet away from the flower and you zoom out, the flower will get very small, so you'll have to walk closer to the flower to keep it the same size in the picture. However, because you've zoomed out, the optical properties of the lens will cause the distance between the mountain and the flower in the photo to have greatly increased. While the photo taken at 50mm will have it appear that the mountain is a mile away, the exact same photo taken at 10mm will have the mountain look many many miles away -- but the flower will be in the exact same spot. In fact, the mountain might be tiny, perhaps smaller than the flower now. Similarly, if you zoom in, there is the opposite effect. Let's say you decide to shoot at 200mm. Of course, you will need to step pretty far back from the flower to keep it the same size in the frame. Maybe many yards/meters away. When you look at the final photo, the mountain that previously appeared to be a mile away when you shot at 50mm, may now appear to be right on top of the flower, perhaps just behind it by a few feet. This is the magic of focal length. This may come into play in almost any photo you take. If you're taking a picture of a friend or spouse, it is entirely up to you to decide what you want behind your subject. If you're in a city, you can make it appear that an entire cityscape is behind them by zooming out and stepping closer, or you can zoom in, step far away, and put them practically inside one building! It's really up to you. My advice is to think about this every time you click the shutter. Think about the subject and the background, and how you want each to appear, and make a conscious choice. That's what photography is all about!

FYI, you can try this right from your living room. Place a glass of water on a coffee table and stand so that whatever is behind the glass is at least a few feet away. Zoom to your widest lens setting and frame the shot so that the bottom of the glass is as the bottom of the picture, and the top of the glass is about halfway up the frame. Make sure you can see what's behind the glass and re-adjust your position in the room as necessary. Take the shot. Now we'll take a 2nd shot. Zoom in to your longest focal length and frame the picture the same way by putting the bottom of the glass at the bottom of the picture, and the top of the glass about half-way. When you're zoomed in, you may have to step quite a ways back, probably up against a wall. If you can't get back far enough, just zoom out a little until the glass is halfway up the frame. Take the shot. Now compare the two shots on your LCD. The glass of water should look exactly the same, but the background in the second one will be much much closer.

Fun Fact: Did you ever wonder why professional photographers who shoot models (say for Sports Illustrated calendars or advertisements) shoot with these incredibly long lenses from half way across the beach? It's because "zooming in" and shooting with a long focal length as described above compresses distance...and they're actually compressing the model's face. By shooting at a long focal length like 200mm, you are making the tip of the nose appear closer to the rest of the face (than it is in real life), making the nose smaller, which is usually considered flattering. That's why the "portrait lens" is generally 85mm to 135mm (way more than 50mm!). To use this to your advantage, always try to take photos of people from a reasonably far distance at one of those longer focal lengths (zoomed in). It makes a big difference!

I've also created an app for iPhone, Android, and iPod Touch which teaches you photography -- more info can be found here:

Photography Trainer for iPhone and Android

Photography Trainer iPhone app

Photography Trainer iPhone app

If you have any questions, please feel free to let me know...

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Copyright 2009, Paul Timpa

Comments (2) Trackbacks (0)
  1. Hi Paul, thanks for sharing your very useful thoughts n great pics. Can’t wait for your next tips. Thanks

  2. Thanks so much for the kind words Sadiq. Two more sets of tips coming soon… Thanks again. Regards, Paul

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