digital slr photography for dummies

How To Reduce Noise In Your Photos

Noise is that grainy look digital photos sometimes get, usually noticeable as multi-colored speckles most visible in the dark or shadow areas of an image. Although you can sometimes use noise as a creative effect, it’s generally a bad thing that destroys detail in your image and might limit how much you can enlarge a photo before the graininess becomes obtrusive.

The most common types of noise are produced at higher sensitivity settings. That’s because cameras achieve the loftier ISO numbers by amplifying the original electronic signal, and any background noise present in the signal is multiplied along with the image information.

One reason why point-and-shoot digicams often don’t have ISO settings beyond ISO 800 is that the noise becomes excessive at higher ratings. However, you can boost the information that the bigger dSLR sensors capture to higher ISO settings with relatively lower overall noise. I’ve used digital SLRs that had less noise at ISO 800 than some poor-performing point-and-shoots displayed at ISO 100. Obviously, the larger sensors found in dSLRs score another slamdunk in the noise department and make high ISO ratings feasible when you
really, really need them.

Noise doesn’t always result simply from using high ISO settings: Long exposures can cause another kind of noise. Although some techniques can reduce the amount of noise present in a photo, by and large, digital SLR cameras are far superior to their non-SLR counterparts when it comes to smooth, noise-free images. Thanks to the disparity in size alone, all sensors of a particular resolution are not created equal, and sensors with fewer megapixels might actually be superior to higher-resolution pixel-grabbers.

For example, most older 8-megapixel dSLRs produce superior results to the newest 10-megapixel non-SLR digicams. I’ve seen results from one $3,000 4.3-megapixel pro-level dSLR that runs rings around the best images possible from an $800 EVF model with an 8-megapixel sensor. So no matter how many megapixels a point-and-shoot camera’s sensor can hoard, that sensor isn’t as big as a dSLR’s. And when it comes to reducing noise, the size of the sensor is one of the most important factors.

Why Should You Use dSLR Cameras?

Perhaps you’re not convinced that a dSLR is for you. Don’t feel guilty. Many serious shooters are in the same position. You’ve been getting good results with your non-dSLR camera and wonder if you’ll see any improvement with a single lens reflex camera. Perhaps the 28-200mm (35mm equivalent) zoom lens on an SLR-like camera with electronic viewfinder has the range you need for 95 percent of your photographs. Why purchase a dSLR if you won’t need interchangeable lenses, or can’t afford them?

The truth is that there is a lot more to a digital SLR than the Single Lens Reflex part of the equation. I’ll get into more detail in Chapter 2, but here’s a quick summary of the pros and cons of dSLRs, and why you might get much better results from a dSLR with 6 megapixels when compared with a non-dSLR model with the same nominal resolution. Note that the first bunch of the advantages I’m touting are only incidentally related to the fact that the camera is a single lens reflex.

The Advantages of dSLR Cameras

Higher sensitivity and reduced noise: The images from most non-dSLRs begin to break down when sensitivity is increased to ISO 400 or more, primarily because of excessive noise. Few of these cameras have an ISO setting that’s usable. In contrast, many dSLRs generate relatively low noise at ISO 800, and produce acceptable images at ISO 1600, ISO 3200, and beyond. The improved quality offered by digital SLRs is due to the larger sensors available in these cameras. As vendors pack more and more pixels into the tiny CCD sensors found in non-SLR cameras, the pixels become smaller and more prone to noise. The larger pixels in the CMOS and CCD sensors of dSLRs have much less of a tendency to produce the random grain we see as noise, and are more sensitive, to boot, producing higher effective ISO speeds.

Control over depth-of-field: The larger sensors require lenses with longer focal lengths, so the dSLR use regains the control over depth-of-field that is such an important creative tool. Ignore those “35mm equivalent” specs you see posted for non-dSLR cameras. That “38mm” zoom setting on your point-and-shoot digital may provide the same field-of-view as the moderate wide angle you’ve used on your film SLR, but the depth-of-field is more akin to what is native to the 6mm actual focal length of that lens. You’d think the “380mm” setting would give you roughly the same narrow depth-of-field you’d expect from a 400mm lens on your film camera, but what you end up with is the same field of sharpness offered by a 60mm lens. Anyone who’s used a consumer digital camera knows that at non-macro shooting distances, virtually everything in the picture is sharp, at any zoom setting and at any f-stop.

Digital SLRs work like a camera, not a VCR. I own a Nikon CoolPix 995, which was one of the best $1,000 digital cameras of its time, and still a champ among 3.3MP models for sharp images and macro performance. Still, this camera drove me nuts. Even after I’d owned it for a year I had to take along a cheat sheet that told me how to activate infrequently used features, such as manual focus. I used the 995 a lot, but I still had to refer to my crib notes to see which menu I needed to refer to to activate a particular feature, and then which buttons to press to make it work. It was a great camera, but it didn’t work like one.

The same situation exists today with the vast majority of non dSLR cameras. I have the opportunity to test eight or ten point-and-shoot cameras in all price ranges each month, and virtually all of them operate more like VCRs rather than like cameras. When you zoom in and out, do you want to press a couple of buttons and wait while a teeny motor adjusts the lens elements for you, or would you rather twirl a zoom ring on the lens itself and be done with it? To switch to manual focus, wouldn’t you prefer to flip an AF/MF button and then twist the focus ring on the lens, instead of pressing a Menu key, finding the Focus setting, switching to Manual focus, and then pressing a pair of left-right cursor buttons?

Photo enthusiasts won’t put up with that nonsense when they’re trying to take pictures. The dSLR I use has separate buttons for burst mode, ISO settings, white balance, EV adjustments, metering mode, and resolution. To adjust any of those, I hold down the appropriate button and thumb the command dial to choose the setting I want. Set the camera to shutter- or aperture-priority (with a dial, not a menu) and move the command dial to adjust the f-stop or shutter speed. In manual exposure mode, there are separate command dials for shutter speed and aperture. That might seem like a lot of buttons to master, but, trust me, you’ll learn to use them much more quickly than you’ll memorize the menu system of the typical point-and-shoot.

Faster operation: You’ll find that dSLRs work much faster than point-and-shoot digital cameras. One of the metrics used to measure point-and-shoot performance is “time to first shot.” That is, once you decide to take a picture and switch the camera on, how long must you wait until the camera is actually ready to shoot? Generally, you’ll have to wait 3 to 5 seconds or more; then wait another second while the camera autofocuses and calculates exposure after you’ve pressed the shutter release. Switch a dSLR on, and it’s ready to go. On more than one occasion I’ve spotted an unexpected opportunity, switched my digital SLR on as I brought the camera to my eye, and then took a picture, all within less than one second.