Monday, June 25, 2007
D-SLRs: Entry-Level, Midrange, Pro
What’s the difference?
All D-SLRs will shoot RAW images as well as JPEGs, while few compact models can shoot RAW images. RAW images provide better image quality than JPEGs, in part because they're uncompressed or compressed losslessly while JPEGs are lossy compressed, and in part because RAW images are 12-bit while JPEGs are 8-bit.
Another big plus for D-SLRs is their autofocusing systems. Compact digital cameras use contrast-detection AF systems, which require a number of readings to determine and establish focus. D-SLRs use phase-detection AF systems, which can determine and establish focus with a single reading. Thus, D-SLRs autofocus much more quickly than compact digital cameras—important when photographing action subjects.
All of today's D-SLRs provide shutter speeds from 30 seconds to 1⁄4000 sec., with nine models going to 1⁄8000 sec. (and the Nikon D2Hs to 1⁄16,000 sec.). All also provide B settings for longer exposures. This, along with the SLR finder and phase-detection AF system, gives the SLR user a huge advantage over the compact user when shooting action subjects.
All of today's D-SLRs offer program, shutter- and aperture-priority auto-exposure modes, plus metered manual exposure control. All also offer multisegment and center-weighted metering. Many also offer spot or small-area metering, which lets you meter a specific portion of a subject or scene. All provide exposure compensation, flash exposure compensation and automatic exposure bracketing.
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