What exactly is wide angle?
To answer that question we have to answer another: what is normal? Some people think that normal is the focal length of the eye. That would be wrong. Technically, the focal length of the eye is somewhere around 22mm (FX equivalent). That would be what we generally consider a wide angle lens. No, "normal" usually refers to an aspect of perspective, not angle of view. A normal lens is usually defined as having the same focal length as the diagonal capture (DX: 28mm, FX: 43mm). This produces a "normal sized print" that has a "similar perspective" to what we'd see in real life if we were standing there.
Wide angle lenses for DX currently fall in the 8mm to 24mm range, for FX we have 12mm to 35mm available. Here's the thing to think about with wide angle lenses:
- If you stand in the same place with a wide angle and normal lens you get a wider angle of view (more things to the sides now appear) with the same perspective.
- If you stand closer with a wide angle than you do with a normal lens you get a different perspective that exaggerates depth relationships (near/far).
- If you stand further away with a wide angle than you do with a normal lens you get a different perspective that removes depth relationships.
Most beginning photographers try to use a wide angle lens in the first manner. Most pro photographers use a wide angle lens in the second manner. A few really pro photographers will sometimes use a wide angle in the third manner, because it emphasizes what they're trying to show with the composition.
The problem with the first use is that it tends to remove depth relationships in order to show more "width." But photographs are two-dimensional when presented (at least the vast majority at this point in time). "More width" in a 14" print doesn't really help to make the image more involving; it tends to have the opposite impact. Removing depth clues makes an image look very "flat" and tends to make the viewer feel distant (which is what the pro attempting the third use is probably trying to emphasize).
What I've long taught at workshops is this: the wider the lens you use, the closer you probably should be to the nearest thing in your scene. And there should be a nearest thing in your scene! The classic landscape shot is something like: near flower, middle lake, far peak. How far do you think the photographer is from the flower? The lake? The peak? How about 1 foot, 10 feet, 1 mile+? Yep, there's almost a logarithmic nature to near/middle/far in most pro landscape shots. In most amateur shots, it's more like middle/far/far (10 feet, 100 yards, 1 mile). And the image feels "flatter" when hung on the wall in a frame because of that.
This is not to say that you always frame a wide angle with near exaggeration, but I'd want to hear a clear plan on what you're trying to achieve by removing depth perspective if you're going to try something else, like standing back.
Is there a sweet spot? Yes. Though it has tended to move over time. Back around World War II it was probably enough to use a 35mm lens. The difference in perspective (when used correctly) was enough to distinguish such pictures from those shot at 50mm and 55mm. ("Normal" was a bit longer than it should be during that period because longer lenses were easier to make sharp.) Over time, that has changed, though. By the time Galen Rowell became one of the preeminent 35mm landscape shooters in the 80's and 90's, 20-24mm was where things stood for "wide angle." I'm not sure they've moved beyond that, though. That's because it gets more difficult to find things you can photograph at <6" coupled with things that are near infinity and which make any sense. 24mm (FX; that's 16mm DX) is good, when used properly. 20mm (FX, or 14mm DX) produces a bit more perspective exaggeration, but is trickier to get right, and starts to be a problem if there are people in your shot outside the central area. Wider than that generally needs a very specific set of near/middle/far relationships and someone who is clearly manipulating those.
So, let's break this out for DX and FX users.
- First, FX: you need a 20mm or 24mm lens to get strong depth perspective changes. Anything wider than that gives you some flexibility in really close or tight quarters (e.g. indoor shooting). So we've got plenty of great choices for wide angle: the 14-24mm f/2.8, 16-35mm f/4, 24mm f/1.4G, and 24mm f/3.5 PC-E lenses come to mind, plus we have the 24-70mm and 24-120mm zooms. Just make sure that you have a way to get to a very usable 24mm. Unfortunately, the 18mm and 20mm lenses Nikon produced don't do very well on the digital bodies, so we end up going to zooms in that range over primes.
- DX users need at least 16mm. That really only gives us zoom lenses: the 16-85mm f/3.5-5.6 DX, 16-35mm f/4, 10-24mm f/3.5-5.6 DX, 12-24mm f/4 DX, and perhaps the 14-24mm f/2.8. The 14mm f/2.8 isn't all that great—I'd rather have any of the zooms. This once again points out the fact that we don't yet have any usable DX wide primes. Surely someone at Nikon must have noticed that, which means that Nikon thinks you don't need a wide DX prime. That would be a wrong decision, and surveys of Nikon users tend to prove that point.
You can certainly go wider (14-24mm on FX gets you to a very wide 14mm, and the 10-24mm on DX is nearly as wide at 10mm). But make sure you know how to frame for depth with these lenses and that they're really what you need. I find 14mm on FX and 10mm on DX a much more conditional use than a basic use. On FX most of my wide landscape work would tend to be 20-24mm, on DX 14-16mm.
I should point out that we have some "fun" wide angles, too. The fisheye lenses (e.g. 10.5mm DX and 16mm FX) definitely provide a completely different perspective. They are a bit tricky to master, but using them is almost like playing a game, trying to figure out how to "score" with an image using them.
Almost everyone reading this certainly has a wide angle lens of some sort. Even the kit lenses on DX give you a 28mm equivalent, which is within the wide realm. But here's the thing. Learn just one thing and it might open up a new wide angle world for you: get closer. That's it. Get closer. If you're a wide angle newcomer, just try this: move two full steps closer when you're at 18mm on your kit lens. Resist the temptation to move backwards to "get everything in." (Uh, if you're standing at the edge of a cliff, cancel that move two steps closer order. But you'd find me laying on the ground and hanging a bit over the cliff. ;~) If you're photographing people in front of things, moving closer is going to mean you have to move the people out of the center of the image, too. And note that "get closer" may also mean you need to get closer to the ground. You're not going to get depth perspective enhancement from eye level if the nearest thing is at your feet.
Trust me on this: just try moving closer when you zoom out or change lenses to a wide angle. You'll discover your images are suddenly different, and have depth to them they didn't have before.