Photography

Executive summary: Buy a digicam. Turn off the flash. When shooting a scene:

  1. Set the exposure.
  2. Set the ISO as low as possible while keeping shutter speed faster than 1/10 second. If subject is moving set ISO so shutter speed is faster than at least 1/60 second.
  3. Frame the scene loosely.
  4. Take many, many shots.

The goal of the amateur digital photographer should be to capture an image with the right exposure, framed no tighter than desired, with the best image (sensor) quality possible, and without using a flash.

Any good digicam gives you control over five dimensions: Zoom, focus, exposure, sensitivity (ISO), and flash. (It will also allow you to adjust shutter speed and aperture. Aperture on a small lens has little practical effect, so we can ignore that dimension with digicams. Shutter speed is a direct function of exposure, ISO, and flash, and since digicams do not deterministically adjust those parameters to hit a desired shutter speed it is better to set the first three intentionally instead of hoping that the camera makes the right tradeoffs.) If you only pay attention to exposure and sensitivity you can get the best photos from your digicam. Here’s why:

Zoom: It is so easy to crop a digital image that you should not spend too much time fine-tuning the zoom. Err on the side of taking in a wider scene than you want — you can always crop, but you can’t expand the picture after the photo has been taken. With sensors capturing more than a few megapixels you can crop aggressively and still end up with smooth prints up to 8×10.

Focus: With the small lens characteristics of digicams you don’t have to worry about focus for anything but extreme close-up shots. In any case, autofocus is handled at the same time the exposure is set, so assuming you want to focus on the same subject you intend to expose you can leave the task of focusing entirely to the camera.

Flash: It is nearly impossible to take a good photo with a compact, camera-mounted flash. Therefore the goal of an amateur photographer should be to never use the flash! Only if you’ve done everything else possible with the camera and still can’t get a reasonable exposure should you consider turning on the flash. (At which point you should pause to ask yourself if it’s even worth taking such a bad picture.)

Exposure: Most digicams allow you to adjust the exposure, quantified as Exposure Value (EV), and typically within a range of +/-2EV. By adjusting the EV you are telling the camera to collect more or less light than it thinks it should. It is worth playing with this setting to become familiar with the effects. In essence, when you lock the camera onto a subject it will take a guess on how much light to let in. When lighting is uniform this guess is usually very good. But when there are shadows, backlighting, or other dynamics the camera may guess poorly. An underexposed subject is left in the shadows. An overexposed subject can be washed out to the point of looking like a uniformly bright blob. Under- and over-exposure are collectively referred to as “clipping.” In the real world many scenes have such a wide range of light that even the best sensors will have to clip something. Whatever has been clipped in the image your camera captures cannot be recovered. It is possible to adjust image exposure with photo software, but you can usually only make small changes before you begin to clip even more of the image — essentially washing out even more details. This is why getting the correct exposure is so important!

Sensitivity (ISO): ISO values describe how sensitive the image sensor of the camera will be to light. But there is a tradeoff: The higher the sensitivity, the higher the noise. Noise appears on images as graininess and inaccurate colors. Essentially, when you raise the sensitivity of your camera’s image sensor you’re asking it to guess what the true color of each pixel is with fewer photons to make that guess. So as you raise the sensitivity (ISO) value the sensor spends less time guessing — which gives you faster shutter speeds — but the guess gets worse and worse. It is worth testing the upper limits of ISO settings to determine at what point your camera’s image sensor begins to degrade.

That leaves you with just two independent, and one dependent variables to control. And this is where you should put your attention: Exposure, ISO, and shutter speed. Having picked the exposure necessary to capture the scene lit the way you want, you now have to trade off sensitivity and speed. Higher speeds compensate for movement, which blurs the image — either because you’re not able to hold the camera still on the scene, or because the subject is moving. If your camera has an optical image stabilizer you should be able to get away with 1/10 second shutters. Otherwise anything slower than 1/20 second is shaky. If your subject is moving you will need much faster shutter speeds.

Press the shutter down half-way. Your camera will lock on to something in its field of view, focus on it, pick an exposure, apply an exposure adjustment if you have asked for one, and then tell you how fast the shutter will be when you take the picture. If the shutter is too slow, raise the ISO setting. If it’s faster than necessary take advantage of the extra light by lowering the ISO setting to get a better image.

If you’re used to film cameras you need to make one other paradigm shift: Take as many pictures as possible! Don’t waste time framing or waiting for your subject to adopt the perfect pose when you could instead hold down the shutter and get a plethora of shots — including the one perfect moment you would have missed if you tried to time it. (Note that this high-quantity strategy is what film professionals always did to get professional photos — though at much greater expense.) You can always delete extraneous or bad photos. But you can’t go back in time to try to capture a perfect photo if the shutter wasn’t open.

Digicam

I have used Canon A-series digicams for years. The A590IS — now selling for just over $100 — represents an exceptional value and I would not hesitate to recommend it to anyone who doesn’t need either a compact camera or else the extra features of an SLR.  For in-depth recommendations and reviews of cameras I recommend Imaging Resource.

Movies

One other feature to note with many digicams is the ability to shoot very good movies. With optical image stabilization videos can look tripod-steady even when you’re just holding the camera. Typical high-resolution video modes shoot 640×480, which is DVD quality (“480p”). (One strange thing with the A590IS is that the top frame rate in that resolution is 20fps, whereas its predecessor A570IS, which I still use, gives 30fps.)  Audio is monochannel but otherwise these videos beat every analog camcorder I used in the past.

I haven’t had a chance to try them yet, but I am intrigued by Casio’s Exilim digicams which can capture 480×360 video at 210fps — a frame rate that would reveal rapid action not visible to the naked eye and provide very smooth slow motion effects.

Digital Single-Lens Reflex (DSLR)

When you step up to a DSLR you get access not only to a wide variety of more powerful lenses but also to much better sensors. Also with bigger lenses the aperture setting becomes a significant parameter you can manipulate to make tradeoffs between focal range and light collection.

SonyAlpha300_w_lensesI bought a Sony A300 for two reasons: Live view, and built-in optical image stabilization. Sony is no longer the only DSLR maker with these features, so there is no excuse to buy a DSLR without them. “Live preview” allows you to use the LCD display on the camera body to frame the shot, instead of having to put your eye right up to the optical viewfinder. In-body optical stabilization allows you to use slower shutter speeds than you would without it. If you don’t get it in the camera body then many systems sell stabilizing lenses, but that means that if you want the feature you have to pay for a new stabilizer in every lens.

DSLR sensors are more powerful than the smaller ones used in standard digicams, which means that you can shoot with lower light and higher ISO settings before you start to see image degredation. DSLR lenses are bigger than typical digicam lenses, which means they gather more light. When I put a 50mm f/1.7 lens on my A300 I can take great photos in dim indoor light — without a flash!

CanonA570_and_SonyAlpha300That said, if you don’t plan to use multiple lenses you should consider higher-end digicams.  These compete favorably with DSLRs and are both smaller and cheaper because they don’t have to support independent lenses.

Another drawback with DSLRs is that they can’t capture video, although Nikon just released a D90 model that does.

I consider “live preview” functionality to be essential, so I would not buy a DSLR without this feature.

Software

Windows chokes on more than a thousand or so high-resolution image files. If you’re taking hundreds of shots per scene that need to be filtered down to a few good ones you want to keep, and if you’re storing libraries of thousands of digital photos, you’ll want software designed for the job.

I have been using ACDSee. It efficiently caches and thumbnails directories containing thousands of photos. It provides batch processing of any manipulation, so if you want to rotate, crop, or adjust exposure the same way on a set of photos you can do them all in a single step. It supports extensive tagging, rating, sorting, filtering, and comparing. It can view and modify all EXIF image properties. It also offers exceptional light balancing tools which can enhance poorly exposed photos without clipping. I don’t know if it’s the best package out there, but I’m satisfied with it.

7 thoughts on “Photography

  1. Brian

    Hey – I stopped reading after the statement “Set the ISO as low as possible while keeping shutter speed faster than 1/10 second.”

    This is incorrect. Its nearly impossible, even for stills, to get a good image with only 1/10th of a second. The shutter should be 1/30th at the slowest and the number goes up with added focal length. A good rule of thumb is 1/focalength. So, for example, with a 100mm focal lenth then the shutter shoud be at least 1/100

  2. federalist Post author

    That’s an obsolete heuristic. Now virtually all digital cameras come with optical image stabilization that makes it easy to get good still exposures at 1/10 second. For shorter focal lengths if you brace yourself and are careful with your trigger finger you can hold the shutter open for extended periods without any smearing of the image. For example, I captured this photo holding the camera with the shutter open for 4/10ths of a second.

  3. Brian

    Really? You hand held that shot for half a second? The meta data in that image indicates F8 1/2s ISO 100. I did not know that image stabilization was really that capable, If you really did hand hold that shot I stand corrected. Still, with such an image why not use a tripod? I understand the slow shutter to allow for the F8 to give you the depth of field needed for the image.

  4. federalist Post author

    Yes, that was indeed hand-held. Of course it generally makes sense to use a tripod for stills like that, but in this case I was setup on the floor, my shortest pod was too tall, I ran out of lights, and my optical stabilizer saved me the trouble of building a rest for the camera.

    Actually trying extended hand-held stills is probably a good exercise for any photographer — it will teach a lot about both grip/shutter discipline and the limits of each camera’s optical stabilizers.

    On the other hand, camera sensors are getting so powerful that light is becoming less of a constraint, so soon instead of “Why not use a tripod?” you may be asking, “Why not just bump the ISO to 1600?”

Leave a Reply

Your email address will not be published. Required fields are marked *