Your eye has a particular field of view. That is, you can see a particular amount of width with a naked eye. It's a little hard to qualify exactly what normal human field of view is, because our peripheral vision is very wide, but that gets very unfocused at the edges, so usable field of view is a difficult thing to gauge. Things outside of my field of view I can't see. A lens also has a field of view which is determined by the lense's focal length. Technically focal length is measured in millimeters from the middle of lens to the principal point of focus of the lens.
Now you don't actually need to know where these points are. All you have to know is what happens when you change focal length and we will be looking into that extensively later in this course. Any lens that offers the same field of view as the human eye is said to be a normal lens. Here's an image shot with a normal lens and it looks pretty much like the field of view that you would expect to see if you were standing in this location. Again if you were actually there, you would have a larger peripheral sense but that part of your field of view would be very out of focus. Any lens that is longer than normal is considered a telephoto lens. As you go more telephoto your field of view gets narrower and magnification increases.
Things that are farther away appear closer. Any lens that is shorter than normal is considered a wide angle lens. Your field of view gets really wide, which means you can take in a wider vista, but most things in your shots appear small because of this wider angle. So your first important field of view concept is this: as focal length increases, field of view narrows and magnification increases. Trust me you know all this stuff already. When you zoom in things get bigger and appear closer. What you may never have thought of before is that this zooming function results in lessening of field of view. When you zoom out, things get small and you have this nice big wide field of view.
Now it might seem like we're just hassling with putting words on things that you can intuit and feel your way through, but it's very important that we had this terminology worked out for most of what's going to follow in this course. So for example, when I say, "Go shoot with a telephoto focal length," you now know that I mean a focal length that's longer than a normal lens. When I say, "Interiors are best shot with a wide field of view," then you know that I mean a shorter focal length. So you want to know what focal length is normal for your camera, what is telephoto and what is wide-angle. But what is a normal focal length? That depends on your camera's image sensor.
- Understanding field of view and camera position
- Depth of field and lens choice
- How to choose a lens
- Examining lens features
- Using specialized lenses such as fisheye and tilt/shift lenses
- Focusing techniques
- Using filters
- Camera maintenance