October 2006 HelpLine


Image Sharpness Revisited

* Image Sharpness Tip
* Card Reader Or Camera For Download?
* Quest For The Perfect Histogram

 

Another Tip For Image Sharpness: Know Your Limitations

Cameras can be heavy, especially when you add a longer lens to them. An obvious key to sharp images is keeping the camera still. Last month, I gave you a way to practice using a light touch on the shutter release. But if you can’t hold the camera still in the first place, a soft touch won’t help.

A properly setup tripod is the easiest way to stabilize the camera. But if you’re in a situation where a tripod can’t be used, these techniques may help make the camera steady:

• Always support your camera using
both hands.

• Keep your legs apart (that’s how a tripod offers stability). If you can, lean against a wall or other firm object.

• Slow down. Many times rushing to capture an image results in an unusable photograph. All the scurrying around for that one perfect image may lead to disappointment.

• Settle down. Take a couple of normal breaths and then gently exhale while you’re taking the picture. Some suggest that you hold your breath, but I’ve found that holding your breath creates tension in your body. That tension translates to vibration, which travels down your arms and into your hands, which, of course, are supporting the camera.

Card Reader Or Camera For Download?

Q) I just purchased my first digital camera, primarily to reduce the weight I lug around on forays into the Sierras or along the Big Sur area. In reading a digital forum Website, I learned there’s a disagreement, or rather, pros and cons, about the use of a reader or going direct. One person stated he’d never use a card reader because they’re generally unreliable with poorly written software that “can malfunction in a variety of ways.” Another was in favor of card readers because of the drain on the camera battery and the possibility of dying in the middle of a transfer and possible loss of data. What’s your view on the debate?

Pete Margosian
Southern California

A) I’ve long been a proponent (some would say a fanatic) about using card readers rather than downloading directly from the camera. To me, the pros far outweigh the cons.

You’re right about drain on the battery. The rechargeable batteries that come with digital cameras have a finite life span-the technical term is charge cycles. The range of charge cycles might be 500 to 1,000. Once you’ve used up all of the charge cycles, the battery is finished. And you’re right to mention the problem of running out of power during a memory-card download. So instead of using up a charge cycle to download images from your camera, use a reader.

Regarding software, most card readers don’t require it. They’re usually recognized by current Mac and Windows operating systems.

 

 

The same can’t always be said for direct connection of your camera to your computer—for many, you need to use drivers that come on the CD that’s packaged with your camera. Also, the hardwired connection between your computer and the camera can lead to precarious “temporary placement” of your camera. I’ve seen cameras balanced on top of scanners, monitors and computers, where one slip could damage the camera or the connector on the camera.

In addition, a card reader is simple and always connected to your computer. You don’t need to search for cords—just pull out your memory card and plug it in.

Now, to answer a couple of the card reader criticisms. I’ve run across (and thrown out) several cheap card readers that were very frustrating to use. The problem seems to be the guides that ensure that the contacts on the card line up with the contacts on the reader. Eventually, the guides wear out or become misaligned, making the whole setup difficult to use. If possible, spend a little money and get a sturdy reader.

Another issue is learning how to eject the card from the reader. While it’s easy to remove the card physically, first you have to let the computer know that you want to remove it. If you eject the card without letting the computer know, you’ll probably get an error. If you do this while downloading your images, you might end up with corrupt files on your computer. (It won’t corrupt the files on the memory card.)

If you use Windows, let the computer know you’re removing the card by clicking on the Safely Remove Hardware icon in the tray at the right of the Taskbar, then selecting the appropriate device. On Macs, you need to drag the card icon from the desktop to the trash. Once the computer has disconnected the card, you can eject the card from the reader.

In short, use a reader. The only time I have a camera hooked up to my computer is when I’m shooting tethered in a studio or if I need to use the camera software to upgrade the firmware (even the firmware upgrade can usually be done via the memory card and reader).



Quest For The Perfect Histogram

Q) I’ve enjoyed shooting digital for the last year. I’m amazed at how many more good shots I get because I don’t have to wait for the prints to come back to see how good my exposure was. Now I’m trying to improve my exposure technique. While I understand the histogram somewhat, what should the best histogram look like?

B. James
Austin, Texas

A) I’ll make a deal with you. You tell me what the best shutter speed is, and I’ll tell you what the ideal histogram should look like. Okay, okay, I’ll give you an answer with a little less sass.

But first, a little review. The histogram is a graph that displays the tonal values in the captured image. The left side of the graph represents the darker areas of the image; the right, the lighter areas.

The general rule for evaluating exposure using a histogram is that you should avoid cut-off edges (clipping) on the far ends of the graph. These cut-off parts of the histogram represent loss of detail. For example, if you’re taking a picture of a scene with a bright, cloudy sky and your exposure causes the histogram to go up sharply at the extreme right edge of the histogram and quit, you’ve likely lost detail in the clouds. If, on the other hand, you capture an image in a dark forest and the same sort of clipping appears on the far left edge of the histogram, you’ve lost detail in the shadows.

 

 

 

While you often try to adjust your exposure to avoid loss of detail, there are situations in which the contrast in the scene is just too high. Unless you use artificial lighting or graduated filters, you may have to accept some detail loss. You could also use multiple exposures—one exposure for dark areas, one for light ones—and merge them in your image editor. (If you can shoot in RAW mode, you might be able to recover some detail.)

In many cases, the best exposure might have a histogram that displays a uniform set of values across the entire graph, but this isn’t always the case. The histogram reflects the scene, and not all scenes have a standard set of brightness values. Take, for example, a scene of morning mist over a swamp. In this situation, there may not be any dark tones in the scene or on the left side of the histogram.

As a rule, however, be careful of images that graph only on the left half of the histogram. Underexposure like this can overemphasize noise in the image sens
or.

“Ideal” histogram? It’s really image-dependent. A “best” histogram doesn’t look like any one thing. Generally, though, if you stay away from a histogram that’s heavily weighted to one end-particularly the far left-and you avoid clipping, you’ll be on your way toward achieving good exposure.

If you have any questions, please send them to HelpLine, PCPhoto Magazine, 12121 Wilshire Blvd., Ste. 1200, Los Angeles, CA 90025 or helpline@pcphotomag.com.

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