What Lenses to Use When – By Thomas Lester

I found this article on the PICTAGE BLOG. Thanks to Thomas Lester for posting this. Hope you like it as much as I did!!!

“What lenses should I use and when should I use them?”

A prime lens is one that doesn’t zoom. It’s one focal length only. The “which lens” question applies to prime and zoom lenses.

There are four fundamental lens characteristics:

• Field of View & Reach – Field of view is how wide and tall you are going to see through the lens. The wider the focal length of the lens, the greater the field of view. Reach is how far away your subject can be and still fill the frame appropriately for your composition. Field of view and reach are inversely proportional. In other words, the longer the reach the narrow the field of view.
• Distance compression or expansion – Distance compression is the optical effect that makes objects in the frame look closer together than they really are. Distance expansion is the opposite, making objects in the frame look farther apart than they really are.
• Aperture or “brightness” – Aperture, measured in “F Stops” determines the amount of light that a lens allows into the camera. Lenses with larger maximum apertures (smaller F Stop number) allows more light to hit the sensor or film allowing the photographer to work in lower light scenarios. Aperture also affects depth of field. The max size of an aperture is often referred to as how “fast” the lens is. The larger the aperture, the “faster” it is. “Fast” really refers to the fact that at the same amount of light, a faster (larger) aperture will allow you to set your shutter speed faster to achieve the same exposure.
• Depth of Field – This is the amount of area in the fame that will be in focus. Managing depth of field can allow a photographer to isolate a subject or on the other extreme get everything in a room sharp. Depth of field is affected by three factors. Aperture, focal length, and distance from the subject. The smaller the aperture, the shallower the depth of field. The longer the lens, the shallower the depth of field. Lastly, the closer the camera is to the subject, the shallower the depth of field.

Next, let’s understand how these characteristics apply to our lenses.

• Normal lenses – For the purpose of this post, let’s say that a normal lens is 50mm for full frame DSLR cameras and 35mm for crop frame DSLR cameras. These lenses are considered “normal” because they see the world very similarly as our own eyes. They don’t really do any distance compression. They have a field of view similar to our own vision. This is also subjective. Many will tell you that normal is a little bit wider or possibly a little bit longer. But we’ll use 50mm as our watermark today. If you are shooting a crop frame camera you can use 35mm as your “normal”.
• Wide angle lenses – These are lenses that are wider than 50mm. For zoom users, you could have a lens that can zoom out wider than 50 and zoom in longer than 50. When you are zoomed out, consider your lens as a wide angle. Wide angle lenses have a “wider” field of view. The shorter the focal length, generally means the wider field of view. Conversely, this means it has less reach. This means you may need to be closer to your subject. Wide angle lenses exaggerate distance (distance expansion) making objects look further away from each other in the frame. Wide angle lenses also inherently have a deeper depth of field. This makes it a bit harder to “isolate” the focus on your subject, but makes it easier to get your subject sharp.
• Telephoto lenses – Can you guess? Yep, lenses that have a focal length greater than 50mm. These are also referred to as “long” lenses. The longer the lens, the narrow the field of view. Inversely, the longer the lens the greater reach it has. This is great if your subject is far away. Long lenses tend to “compress” distance making objects look closer to each other than they really are. Last, the longer the lens, the shallower the depth of field. This makes isolating your subject easier with a longer lens, but can also make getting sharp focus a bit more difficult.

One last tidbit to mention. Camera shake! Camera shake is evil. I mentioned that the larger the maximum aperture is, the more light is let into the lens. More light, means you can shoot at a higher shutter speed. Higher shutter speed means the potential to have sharper images (less shake). For me, I try to buy lenses with the largest maximum apertures I can find (warning… they can be expensive). Another thing to consider is that the longer the focal length of the lens, the more camera shake is amplified. As a general rule you should minimally shoot at 1/. So let’s say you are hand holding a 180mm lens (or a zoom lens, zoomed to 180mm), you should shoot at no slower than 1/180th of a second. Twice that (1/360th) if you really want things sharp. There are a lot of aids that can help you shoot at slower shutter speeds like a mono-pod, a tripod, or built in Image Stabilization. Each person is different, though, so practice hand holding at different speeds to determine where your “breaking point” is.

Now that you know the character of your lenses, I’ll run through some typical scenarios. Before I do, I’d like to say that I love my 50mm lens. It’s my go to lens and gets used probably 75-80% of the time. I usually start there and choose something different only when it’s characteristics aren’t working for the scenario. I think every photographer should have a fast 50mm lens in their bag.

A portrait session with a nice, but busy background. In this scenario, I like the general color and tone of a background, but i don’t want it to interfere with my subject. My thought is that I want to isolate the focus to just my subject. This means I want a shallow depth of field. Some factors to think about… The faster the aperture, the shallower the depth of field. Also, the longer the lens, the shallower the depth of field. I may pull out my 50mm f1.2 lens. If the background is still too distracting, I’ll use my 85mm f1.2. Still too much, I may pull out my 200mm f2.8, provided I can get far enough back to still frame my subject like I want.

I need to get a full shot of a dining hall all set up for a reception. For a shot like this, you need a large depth of field as well as a wide angle of view. A wide angle lens would be my choice to fit the whole room in the image as well as maximize my depth of field. I’ll usually reach for my tripod and set the aperture around f16 or greater. With my 24mm at f16, you don’t even really need to focus. Everything is going to sharp.

I was just been told that Madonna is going to be leaving her hotel in a few minutes. There’s already a crowd by the front door. You have a close spot, but you are going to have to hold the camera up over your head to get the shot. If I’m close enough, I’m going to pull out my wide angle lens and put the aperture at around f11 or greater if it’s bright enough (or I have flash). Then prefocus your lens in manual to have the to focus around where the front door is. You’ll have a huge depth of field. When she comes out the door, point your camera in her direction and fire away. She’ll be in focus and you’ll be capturing a wide enough field of view that even if you aren’t pointing directly at her, you’re still likely to get the shot.

I’m shooting a senior session down town. I stumble upon a fantastic old door with amazing color. However, the wall surrounding the door is really ugly and distracting. My very first thought is, I need to narrow the field of view. The longer the lens the better in this scenario. A 200mm lens will allow me to shoot my subject and the door only.

A concert venue hires me to get a shot of the audience during a show that they can use to advertise the room for rent. However the night that they booked me had very poor turn out and the room looks fairly empty. If I can focus in on a group and “compress” the distance, it won’t look like there are 3 empty rows between the full rows. I would grab a long lens, get low to not see the empty chairs. The compression will make the rows of people look closer together, therefore more crowded.

I’m shooting a wedding. It’s the scenario and I need to get a shot of the kiss, but I don’t want to be in the way of the guests. This is the perfect scenario for more “reach”, so I grab the longest lens I have and step back to compose my shot.

The wedding reception (or any party) is at full tilt. Drinks are flowing and I need to capture the energy. For me nothing puts the viewer in the middle of the action like a wide angle lens. The wider the better. Fisheye’s work well. Warning… to do this, you have to put yourself into the action. The reason it feels like the view is there, is because your camera was there.

The rings (or other detail shots) at a wedding. It’s hard to beat a macro lens for the little details, but I’ll often use my 50mm as well. Either way, I like to break out the tripod. When you are really close and like to use wide open aperture (shallow depth of field), just breathing can throw the detail out of focus. A tripod will ensure the sharpness of the details.

I want to exaggerate how tall someone is or the size of an area. Wide angle. The wider the more exaggerated. Get close to the subject and angle down (or up) to make the scene stretch out.

I’m shooting a wedding in a dark church. I’m told that I’m forbidden to use flash. In this scenario, I’m going for whatever lens I can get enough light through the lens to get a sharp, properly exposed shot. I have two options: Fast or Image Stabilized. A 50mm f1.2, or f1.4 can be a life saver in these scenarios. f1.2 or f1.4 will usually allow enough light set your shutter speed fast enough to get sharp focus and freeze ceremony action (i.e. people standing relatively still). You can also use an Image Stabilized lens, but they don’t make the shutter any faster. IS (or VR) will usually allow you to get sharp focus, but may not give you a fast enough shutter speed to stop motion.

So, next time you are working a shoot instead of choosing your lens or your zoom factor exclusively on the framing of your composition, think about the other characteristics of your focal length. Visualize in your minds eye how you want the shot to look and then choose your lens or your zoom focal length based on the character you want for the image.

Basics of Photography

I found this article on the Nikon's Website recently trying to get a grasp on the basics of photography. Aperture, shutter speed and ISO and their connection is the basis of every photograph.

Light, More or Less
Let's start by thinking about what's happening with light when you take a picture. The light passes through the lens and then through the shutter before it arrives at either a sensor or a frame of film. The camera's lens and shutter control how much light gets to that sensor or film frame.

Almost every camera lens has a mechanical diaphragm inside that can be opened up and closed down to let in more or less light. The lens opening is called the aperture, and it's referred to using the term f/numbers or, more commonly, f/stops. A large opening, of course, lets in more light than a small one. Unfortunately, this simple fact can get confusing because the large openings are referred to with...you guessed it...small numbers, while large numbers mean that a small opening is being used. Doesn't seem to make sense, I know. Well, it has to do with mathematics involving the length of the lens and the diameter of the aperture. Trust me on this: it's tougher to explain than it is to work with.

What it means in practical terms is that if we want to let more light in through the lens, we have to open up the aperture, which means going from, say, f/11 to f/5.6. Bigger number, smaller opening to smaller number, larger opening. A fast lens (which means one capable of a very wide opening) would have a maximum aperture of f/2.8, f/2, f/1.8 or f/1.4. Most lenses will close down—meaning a narrowing of the aperture—to somewhere between f/22 and f/32. A full stop difference (again, math's involved) means that half as much, or twice as much, light is allowed to enter to reach the sensor or the film.

Timing the Light
The other part of the exposure equation is shutter speed. The camera's shutter controls how long the light coming through the lens gets to hit the media—film or sensor—inside the camera. This length of time is expressed most often in fractions of a second. A very fast shutter speed would be 1/1000 second, and that speed would freeze most action in its tracks. A slow shutter speed like 1/30 second would blur a person casually strolling by. Most cameras offer a wide range of shutter speeds, from as long as 30 seconds to as short as 1/8000 second.

So aperture and shutter speed work together to create an exposure. And there's one more key element—ISO, which refers to the light sensitivity of the film or image sensor. (One of the coolest things about digital photography is that with film cameras we were effectively locked into one sensitivity, often 200 or 400, for the length of the roll of film; with digital cameras, we're able to change that sensitivity rating for every shot if we want to.)

The lower the ISO—100, for example—the more light we need to get a proper exposure. The higher the number—say, 800—the less light we need. Doubling or halving the ISO means we need half as much or twice as much light. Since we need less light with a higher ISO, you might be tempted to use a high ISO all the time, but the problem is, as we go up in sensitivity, we tend to lose some color saturation and gain some noise, which gives pictures a grainy look.

So it's our job to manage exposure to get the sharp, clear photos we want. The key thing to remember is that the three elements—aperture, shutter speed and ISO—are always linked. For photographers it's a balancing act, and so we're always adjusting the shutter speed and aperture for the right exposure and the effect we want.

Of course, you can bypass all of the above simply by setting your camera for auto or program mode and letting the built-in computer do the work. Still, understanding the relationship of aperture, shutter speed and ISO will give you a greater understanding of how to take creative control of your photography.