DSLRs and Close-Up Photography

Digital SLRs (dSLRs) are the almost perfect choice for close-up photography because of the increased accuracy you can get with framing and focusing, as well as the greater control that most dSLRs provide over your picture-taking. Here are a few things to consider when using a digital SLR for macro photography. Some of these also apply to cameras with electronic viewfinders:

• Don't forget to use depth-of-field preview. The digital SLR typically shows you a bright, clear image with the lens wide open and then closes the aperture at the moment of exposure. The depth of field at that smaller aperture is likely to be much greater than what you saw with the lens wide open, so if selective focus is important to you, you'll want to use your camera's depth-of-field preview button to glimpse the true focus just before you shoot. An object that appears soft and out of focus through the viewfinder can be objectionably sharp in the final image, as you can see in Figure 1.
• Investigate add-on focus aids. An SLR image is usually viewed as projected onto a focusing screen underneath the pentaprism/pentamirror. High-end digital SLRs can offer removable focusing screens that can be easier to focus in dim light or in close-up mode. If you have a dSLR with that capability, investigate the focus aids available to you.
• Not all digital SLRs show the full frame. Today, many digital camera viewfinders trim off some of the image, providing only 92-98 percent of the full image. You actually get more than what you saw through the viewfinder, but if absolute framing is important to you, be aware that what you see is only most of what you get.
• Avail yourself of the mirror lock-up feature, if provided. Close-up pictures can be especially sensitive to vibration, such as that caused by a pivoting mirror. (The mirror reflects the lens view upward to the viewfinder, then flips up out of the way during exposure to let the light pass unimpeded to the sensor. This quick up/down flip inevitably provides a tiny amount of vibration, no matter how carefully the camera was designed.) If you're shooting very close or if your exposure is long, see whether your digital SLR has a mirror lock-up feature, which will let you flip the mirror up prior to the exposure. Then, when vibration has been damped, take your picture with the self-timer or remote release.
• Check out bellows, extension tubes, reversing rings, and special macro lenses. These specialized devices can let you get closer, take sharper pictures, and improve your results, especially if you have a digital SLR with a full-frame sensor.
  

tech.yahoo