Use The Zoom, Luke: Camera optics (Digital Cameras part 2)

Camera salesmen, when they’ve exhausted the subject of megapixels, will usually then start extolling the virtues of the lens, particularly the zoom.

Zoom is the second most misunderstood subject of digital cameras. Zoom comes in a digital and an optical variety. Optical zoom actually moves part of the lens to make the image larger. Digital zoom simply cuts the edges off the picture and spreads more pixels between the ones already there. Digital zoom does not add any more information to the picture as optical zoom does, so the result of digital zoom is a larger but fuzzier picture. Optical zoom is the most important, and most expensive, type of zoom. Try to get at least a 4:1 optical zoom. You can safely ignore extravagant claims for digital zoom, and you should never use it if you care about picture quality. This is another good reason for using a camera over a phone; Phones almost never have any optical zoom.

High-end cameras, such as digital SLRs (Single-Lens Reflex; you view and shoot through the same lens) sometimes have interchangeable lenses. While you can get a fixed-lens camera with a 30:1 zoom, the advantage of interchangeable lenses is higher image quality and often better low-light performance. Those high zoom ratios involve a lot of compromises in lens design. If you want to get beyond “snapshots” and take “photographs”, the fixed -lens with 20:1 zoom or better is a good compromise for much less money than an equivalent SLR outfit. A good “superzoom” camera will run $200- $400, while an SLR with several lenses is more like $2000. Eventually, though, if you’re a dedicated amateur or a pro, you’ll want an SLR.

You also get much more versatility with either a superzoom or SLR camera. Full manual mode is a must for creative photography. Very long or short shutter speeds are useful in some situations such as sports and night photography. Manual focus is also important. The image sensor will be much larger, making for a higher-quality final photo. You’ll also (usually) get a real viewfinder (The part you look through when holding the camera up to your eye) instead of having to rely on the screen all the time. Some viewfinders are electronic, i.e., they have a tiny video screen instead of an optical way of looking through the lens, but a real SLR will have a mirror that directs the image from the lens into the viewfinder, so you’re seeing exactly what the camera sees. Many cameras do not have any optical or electronic viewfinder, forcing you to use the LCD screen for every picture. This not only eats batteries even faster, but also makes it harder to hold the camera still since you now have to hold it at arm’s length. You also may have a problem seeing the screen outdoors, especially in strong backlight. If there’s a viewfinder, there should be a way to turn off the screen when not in use.

Closeups of things are a lot of fun. Check to see if the camera has a “Macro” mode, and how close you can get to your subject with it. You will need to use either the screen or Through-the Lens (TTL) viewfinder for close-ups, because otherwise what you see and what the camera sees will be very different.

It’s also helpful to see in the store how long the camera takes to save the picture to memory. If it takes 5 seconds to save, that means you cannot take another picture until then. Check shutter lag also. This is the time between pressing the shutter button and the camera actually taking the picture. If either of these times is excessive, that can prevent you from getting the shot of a lifetime! SLRs and other high-end cameras generally have much shorter lag times.


This post has been adapted from my new book, “Deciphering the 21st Century,” Available now! Click here to read all about it.

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