Every job has the perfect tool. Did you ever hear that? Steve Martin used it in the film “Roxanne”. In photography, it’s very true. If I want to take a picture of a model, or an open sea, or a bird in a tree thirty yards away, I need to use the right focal length with my camera. The problem is which one do I use?
For point and shoot users, the lenses attached to those cameras say 3x or 2.8x, or 4.5x. But this really doesn’t explain a whole lot; it just seems like numbers. What do they mean?For DSLR users, there are all kinds of lenses out there, but which one should you use for your pictures? There is an 18-70, a 50mm 1.4, and 200mm 2.8; where should you turn for each picture situation?
Relax. Sometimes I think we make life and photography more difficult than it has to be. Let’s break it all down. Focal length is the number of millimeters, designated as “mm” after a number on your lens, where the lens is when you shoot your picture.
The lower the number, the wider the view you’ll see in the picture. The average wide-angle lens has a focal length of about 35mm or below. A lens of 18 or lower is very wide, whereas a lens of 28 is still pretty wide-angle, but could be more so. A lens above 35 to about 70mm is considered average, and it’s in this range that the human eye is located. It’s about 58mm. Finally, a number of 70mm or higher is called a telephoto. This means it enlarges things in the lens so that they can be seen more clearly. You would use this to get the bird shot mentioned earlier.
When you watch a professional sporting event, if you see the photographers on the sidelines, you’ll usually see some huge lenses that they have. These are telephoto lenses, some 400mm, 500mm, 600mm or more, in order to get extremely close to the action. If you want to take a portrait of a person, the right tool for this job is about 105mm; that’s because it gives the least distortion to the subject, and creates the most flattering image. Other focal lengths can distort the face, either by making it too wide or stretched, depending on the lens in question. At this point, don’t worry about the numbers 2.8 or 1.4 or whatever that comes after the millimeter designation on the lens. We’ll get to that in another article.
One vital element for picture-taking, as DSLR users, is to remember that if you DON’T have a full-frame sensor on your camera, then the lenses you put on there will be magnified 1.5 times, in most cases. Some cameras may be a little more or less. But what this does is both positive and negative. It’s positive because your zoom lens of 300mm is now equal to about 450mm; but the negative aspect is that a wide angle of 28 is now about 45, which is not wide at all. To get a true wide angle, below 35, you need to START with a 18mm or wider, so that the magnification won’t get you out of range. That is the inexpensive way; the expensive way is to buy a full-frame sensor camera for a couple of G’s.
For point and shoot (which I will call PNS from now on) users, the zoom number with an x, like 3x, means that the most telephoto ability you have is three times the widest angle. If you had a 3x lens, and your widest angle is 28, you multiply those together, 3×28=84. So 84mm would be the closest you could get on that camera. A 10x zoom times 28, would of course be 280mm, which is an impressive amount of zoom for a point and shoot camera.
Now, you have your PNS, or your DSLR with several lenses. You need to decide how to shoot what you place in front of you. If it is the ocean, or a landscape of some sort, with trees, greenery, etc, then a wide angle zoom lens such as the 18-70 would be good, as it would allow you to see a large distance to each side as well as in front of you. Having a zoom lens would allow you to get wide shots, but also the ability to zoom in some and get a variety of other shots, especially if you are trying to tell a story with your photos. You might look at my article on the subject. The PNS shooter would need to leave the lens as widely set as possible, which usually means to press on the left side of the zoom control so it will go out as wide as possible. If you are shooting a model, or an object fairly close to you or you want to shoot something some distance away but still without cluttering up the image with extraneous material, a 50mm or 35-70mm would be good. A PNS photographer would zoom in about midway to the subject with this shot. You would press the zoom control on the right side, with most cameras, to move the lens in closer to the subject.
Finally, a shot like a bird in a tree, or someone or something far away that you want to bring close would be good for a 70mm and up kind of lens. As a PNS shooter, you’d want to zoom in as much as possible with this one, again pressing the control to the right, this time all the way in. It’s vital to recognize that all photographers need a tripod here, especially in the area of zooming in for a close up. Your camera can’t stay steady enough when you have zoomed in like this; it’s vitally important to having a steady picture.
One thing that is very important for both types of camera users and that is distance. Focal length is really the length, or distance, from the object being focused on to the sensor. If you are trying to photograph an interesting bit of detail in some old woodwork, there’s something to remember. Each lens has a very specific minimum distance you MUST be away from the subject in order for it to focus correctly. This distance is different with every lens, and it changes as you zoom in! If you are set at the widest a 18-70 lens will go, and then zoom in for a close-up, your minimum focusing distance may change from 1 foot to 6 feet, and you’d have to move further back to focus. It depends on the lens. So, you must take this into account when shooting.
On a PNS camera, you keep the same lens on there, of course, but there is still a minimum focusing distance to keep track of. If you just have to have this object in focus, and you need to get up close to it, and can’t get it focused, then place your camera in Macro mode, while the camera is zoomed out as wide as it will go. This will allow you to get focused within a few inches of your subject.
On a DSLR, you’ll probably need to have a specialized Macro lens to be able to do this task, or a regular lens with a Macro feature built in. Remember, also, that you must have a tripod, or you simply won’t be able to get a good, steady, clear photograph.
What is very important to remember is that are no hard and fast rules here. Photography is an art, and it lends itself to experimentation, and I would suggest just that; experiment with your lenses before you go off on a major adventure. Learn what each lens does before you go off with it; be ready to take a lot of pictures. The great thing is that with a digital camera, you don’t have to worry about making mistakes, because you will. The fun thing is learning from them, and then deleting them. With this information that you learn from shooting in the above described ways, you add power to your photographs; power that will make the right kind of lens for each situation the obvious choice.
by David Bradley