Sunday, October 23, 2011
Most point-and-shoot cameras have zoom lenses that incorporate wide-angle to telephoto lenses. One Panasonic Lumix model has a 24 mm to 384 mm reach. To put this in perspective, our staff’s widest lens is a 24mm and our longest is 300 mm. The 300 mm is a special sports lens. It has a large, fast f2.8 aperture and weighs more than five pounds. The Lumix pocket camera weighs a little more than 7 ounces. You won’t get the same quality or be able to photograph in low light like with our newspaper gear, but the fact that you can put this camera and lens combo in your purse or jacket pocket and hardly notice it is impressive.
If you have cameras or lenses with great zooming capability, it’s good to know how to manage their use. For the next couple of columns I will look at how subject matter, light, location and other elements can influence lens choice.
I’ll divide lenses into lenses categories: Wide-angle (24mm to 35mm), mid-range (50 mm to 85 mm), telephoto (105 mm to 300 mm), super-telephoto (larger than 300 mm) and macro.
In this column I’ll consider the telephoto and super-telephoto lenses together. At work, my telephoto use consists of a 70 mm to 200 mm and occasionally a 300 mm. I reach for these lenses for two reasons.
If I’m unable to physically get near a subject, the telephoto lens enables me to bring the subject closer. A grizzly bear across a stream or athletes in the middle of a field are two examples of subjects that would give me reason to grab these lenses.
When I want to isolate a subject from its surroundings or background, a telephoto is an effective tool. Because of their optical design, telephoto lenses create a more shallow field of focus, which helps eliminate distracting backgrounds. It also places more emphasis on a subject. In close quarters, a telephoto lens is an excellent way to tightly compose on a person’s face.
But there are some cautionary notes about telephoto lenses. They are harder to hold steady and may require more light for correct exposures. A good rule to follow in order to avoid camera shake is to maintain shutter speeds equal to, or faster, than the length of your telephoto lens. A minimum shutter speed for a 300 mm would be 1/250th, ideally 1/400th. This helps ensure that you can still hand-hold your camera and not end up with motion blur or camera shake. Cameras with built-in image stabilization can help. The other issue is that consumer-grade cameras like the Lumix, have smaller apertures on the telephoto end of their lenses. As you zoom in on a distant subject, reaching super telephoto Nirvana, your aperture is shrinking, requiring more exposure compensation. It’s a photographic Catch-22. One way to help manage these two issues and increase your chances of success with telephoto lenses is to put your exposure setting on Shutter Priority or TV (time value), and set an appropriate shutter speed to match your telephoto lens. This will maintain a shutter speed that should eliminate camera shake and allow your camera to automatically adjust the aperture to maintain a correct exposure. So go ahead. Zoom in, watch your light and hold her steady. Next week, we will go wide.