Lens Length Comparison

I've had a few questions about the differences between a 35mm and an 85mm lens and what the various focal lengths mean for your photos so I thought I'd try to give y'all a quick lens overview.

There are three general categories of lenses: zoom, prime or fixed, and telephoto.

Zoom lenses are just what their name implies. You can change the length of your lens on your camera - no need to move closer or back away from your subject to change the scene. Some examples of popular lengths are 28mm-70mm or a wider 16mm-35mm. I have a Tamron 28mm-75mm f/2.8 that is wonderful for vacations or day trips. It will work in a variety of situations and you won't spend half the day switching out your lens.

Prime or fixed lenses are a set focal length. In order to change the scene you have to move your feet, getting closer or backing away from your subject. Good examples are the "nifty-fifty", the 85mm and the dreamy 135mm.

Telephoto lenses are typically zooms, they are adjustable lengths, but they are really long. These lenses are often used for sports or wildlife photography. When my kids get old enough for team sports I'll probably want to invest in a good telephoto like this 100mm-400mm to help me capture the action on the field from the bleachers.

So what should you look for in a lens?

Some people prefer to shoot with zoom lenses all the time because of the increased flexibility. I personally prefer a fixed focal length. I can't say why for sure except that maybe I just like to know ahead of time what the scene will look like when I look through the viewfinder. Also, prime lenses are usually a little sharper than zooms. There are fewer moving parts and they can focus just a little quicker than a zoom.

Focal length also plays a roll in how much of your scene is in focus.

Let's look more closely at these photos of my wild children in the backyard. :) I set it up to keep my settings and the distance between the camera and subjects the same. Also, these are pretty bad photos, but they do the trick for what I wanted to share.

Here's my wide-angle 16mm example.

16mm / 1/800 / f/2.8 / ISO 640

There's way too much going on in this photo. You really don't want to see this much of my backyard. :) And most of it's in focus even with the wide open aperture of f/2.8.

When would a 16mm lens be awesome? At the beach. In the mountains. At sunset in an open field. I bought the 16mm-35mm f/2.8L before our beach trip last fall, and I had so much fun with it. It's a great lens!

35mm / 1/800 / f/2.8 / ISO 640

We're pulled in a little more here. There's still too much going on, but it's less pronounced than the 16mm example. I leave my prime 35mm f/1.4L on my camera all the time. It's a great length on my Canon 7D which is a crop sensor. It's perfect for indoor shots. I can get really close to my subject (my kids) and can still get a big enough aperture - I often shoot at f/2.0 - to blur the background quite a bit.

50mm / 1/800 / f.2.8 / ISO 640

The 50mm focal length is a very natural length. It captures the scene pretty closely to what your eyes see. The "nifty fifty" is a great starting out lens because it's a good length and opens up to a f/1.8 aperture allowing you to get a blurrier background than a lens that stops at a f/4 or f/5.6 like a kit lens, but it's super affordable.

85mm / 1/800 / f/2.8 / ISO 640

The 85mm lens on a crop sensor is getting kind of long. I'm standing a long way back from Caroline, but she's clearly popping off the background. You can get pretty good bokeh with an 85mm lens, and it's a great portrait lens because of this. I've been enjoying this lens a lot lately as we've been playing outside more often with our pretty weather. This is a tricky lens to use indoors. You have to put quite a bit of distance between you and your subject so it's really more useful for an outdoor setting.

I hope this helps to clear up your lens length questions. There are a lot of wonderful lenses out there. If you're shopping for a new lens my best advice is to decide what its primary use will be and then get the very best lens you can afford in that category.

I know it's a lot to think about so please leave any questions in the comments, and I'll be happy to get back to you!

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