Before I got my first DSLR, I would hear my photographer friends speak of their 18-200mm's, their 24-70mms, and their sweet 85mm primes. When the topic of lenses arose, I would just smile and nod, having absolutely no idea what any of these numbers meant. Again, this section is not meant to be the gospel of lenses, just some info I've picked up along the way.
First, to sum up the whole "numbers" thing.
The smaller the number, the wider the angle of the lens. So a 16mm lens would be very wide, great for shooting landscapes, groups of people, or architecture.
The higher the number, the greater the zoom. A 400mm lens would be great for photographing animals from a great distance. Make sense? Good.
As humans, we see at approximately 50mm, so that should act as a good reference for some of these numbers.
There are (more or less) two different types of lenses; zooms and primes.
Here's the biggest differences. Zooms can… well… zoom! With a zoom you have a good amount of flexibility by being able to zoom into or away from your subject.
So why would anybody want a prime? Primes can't zoom, so you need to "zoom with your feet" (you know, if you want to zoom closer, just step forward) . However, the way I think of it, prime lenses are only built to do one thing (say, shoot at exactly 85mm), and they do that one thing incredibly well. So, while you lose the flexibility of a zoom lens, you get better quality glass, which hopefully translates to better quality photos. Prime lenses also tend to be much more expensive, but you certainly get what you pay for.
Full Frame VS Cropped Sensors.
Ok, so this topic should technically fall under camera bodies, not lenses, but it has a huge effect on how your lens looks!
If you spent under $2,000 on your camera body, chances are you have what's commonly referred to as a "cropped" sensor. A camera with a cropped sensor essentially multiplies the focal length of your lens by approximately 1.6 (1.5 for Nikon).
So, your 50mm lens actually looks like a 80mm. Your 24mm actually looks like a 38mm. Your 100mm lens actually looks like a 160mm. See a pattern here? Everything is more "zoomed in" with a cropped sensor camera.
Well, is that good or bad? Ask yourself "What do I take pictures of?" If your photos require a greater zoom (sports photography, concert photography, animal photography) then having a cropped sensor might be a huge benefit. If, however, you're always taking photos of landscapes, large groups, or architecture, having a camera with a cropped sensor might be working against you.
Moving up to a full frame camera is expensive, but, photography is expensive…. sigh… Again, you get what you pay for.
50mm on a full frame sensor
50mm on a cropped sensor (80mm equivalent)
Now for my favorite part, practical examples!
Keep in mind that I shoot mainly portraits. :P
10mm on a cropped sensor (16mm equivalent)
24mm on a full frame sensor.
Shooting with a very wide angle lens, and shoving the camera right into your subjects face, will cause the "bobblehead" effect. This usually looks terrible on people, but always looks cute on animals. If you want your subject to look "surreal" or "cartoonish", then it's not a bad idea to shoot in this fashion. In the photo of Caitlin above (the blue haired girl, not the puppy), I wanted to make her look as much like an anime character as possible, so I shot her very wide and close up, causing her head to look much bigger then the rest of her body (also, the photo is unedited, and was taken in my kitchen… so don't mind the mess).
200mm on a cropped sensor (320mm equivalent)
140mm on a cropped sensor (224mm equivalent)
When shooting a portrait, it's always great to work with a telephoto lens (one with a great zoom). Step back, and zoom in to take your subject's photo. This makes sure the facial features don't distort, like in the bobblehead photos. It also does a great job of blurring the background, making for a nice clean portrait.
Ok, so there's one more thing I'd like to mention about choosing a lens.
Head to canon's website, go to the Telephoto Zoom section, and look at how many 70-200mm lenses they sell.
There's five, right? And they range from $700, to $2,500. So what's the difference, and what one do you choose?
Basically, the biggest difference is going to be the maximum aperture of the lens (how wide the lens can open, and how much light it can let in). There is a significant difference between the f/4 model, and the f/2.8 model. But, do you need it? If you find yourself indoors, or in low light situations often, then the 2.8 model is absolutely the better way to go. If, however, you're constantly shooting outdoors, and light is never an issue, you might be safer to save the money and go for the f/4 model. The other difference is the IS, or image stabilization. When you're zoomed in all the way to 200mm, camera shake is a big problem. The IS helps by reducing the shake in the lens. It's especially handy if you shoot a lot of video with your DSLR. However, like anything, it will cost you. The f/2.8 IS lens is $2000, and the Mark II version (with improved optics) is $2500.
So, if you've actually read this entire tutorial/rant on lenses, I'll reward you with a great piece of advice. Rent before you buy. Just go to www.borrowlenses.com and test out whatever lens you're thinking of buying for a few days before making the purchase. You may find out it's just not the one for you, or you may find that it's something you can't live without (which makes spending $2,000 on a lens that much easier).
So what lenses do I use?
Currently I'm working with a 24-70mm f/2.8, a 50mm f/1.4m and a 70-200mm f/2.8 .
What lenses am I drooling over? All of them.
So, enough about gear! Part 3 on Composition is coming tomorrow!