Lenses, field of view, perspective and other good stuff
Welcome back to the blog. Today I am going to talk about and show some photos which look at the field of view of different lenses, then we are going to look at perspective so that you can see the difference between the two. It is not a technical article with calculations and charts. Just a practical demonstration so that you can have an example to start you thinking about what lens you might choose to photograph a particular subject. In these examples I am using 35mm film, different film formats will have different fields of view for the same focal length. The principle remains the same just the numbers change.
Let’s start with field of view. This is basically just referring to how narrow or how wide the scene which you are pointing your camera towards is going to be recorded on your photo. In 35mm cameras a 300mm lens has a narrow field of view and a 24mm lens has a wide field of view. The first series of photos were all taken from the same spot. The camera was on a tripod, exposure was 125th of a second at f8 and the film was FP4 plus.
Click through the images below see the difference in angle of view of lenses from 300mm through to 24mm. An important thing to remember is that when you have the camera fixed in one spot like this and change lenses, the only thing that changes is the field of view.
But wait, doesn’t a wide angle lens distort the subject as well you ask? Well when we are talking about conventional lenses such as the 24mm, no it doesn’t. In fact, have a look at the two frames below, the image on the left is the 300mm image and the image on the right shows a section of the 24mm image which has been zoomed and cropped to show the same portion of the scene. As you can see if you look past the grainy pixelated mess, the proportions of the tractor and the hills in the background are the same.
Left is the scaled down view of the 300mm lens shot. Right is a magnified crop of the 24mm lens shot. The perspective is the same when the photos are taken from the same spot.
So if just changing the lens doesn’t cause a change of perspective, what does? If you want to introduce perspective effects into your photos, you will need to change your camera to subject distance. The next series of photos attempt to keep the subject a similar size in the frame as I change lenses. Have a look at the way that the tractor changes and the way that the background hills recede as the lens widens.
What this means is that you can think about selecting a lens to give the sort of perspective effects you would like to see in your photo. Telephoto lenses to show distant objects larger in the frame, effectively compressing the scene and wide angle lenses will show close parts of the scene large with the size of an object decreasing rapidly as it gets further away from the camera. The samples below show the difference in the way that a 300mm lens compresses the scene and a 50mm lens
Go out and experiment for yourself. Also, if you don’t have lots of lenses, that can be a good thing as well. if you only have one lens just get out and take photos with that, you don’t have to waste any time thinking about this stuff, you can enjoy taking the best phots you can with whatever gear you have with you.