Saturday, August 31, 2013

Battle Of The DSLRs

By The Editors Published in Cameras
Battle Of The DSLRs
The pro DSLRs not only are faster than lower-end models, but they also have bigger buffers, allowing you to shoot longer continuous bursts. Lower-end DSLRs have much smaller buffers—in some cases, a few RAW files will fill the buffer. With these, you'll either have to settle for brief bursts or shoot JPEGs. The Nikon D4's buffer can hold 92 12-bit losslessly compressed RAW files or 170 Large Fine JPEGs, while the D800's can hold 21 RAW or 56 Large Fine JPEGs, and the D7100's buffer, 7 RAW files or 73 Large Fine JPEGs—one reason why Nikon pro action shooters like the D4. Note that the lower-end DSLRs aren't likely to be able to maintain focus on a fast-moving subject for more than a few frames, so big burst capacity isn't really needed.

Ruggedness And Reliability

Pro DSLRs are built for professional photographers, designed to withstand the rigors of full-time field use. Entry-level DSLRs are built for users who don't shoot a lot and don't put their cameras through the wringer. The all-out pro models have more magnesium and less engineering plastic in their construction, entry-level models, mostly plastic, and mid-level models, somewhere in between.

Pro DSLRs are well sealed against moisture and dust, and have proven themselves in harsh field conditions for years. We've also heard many reports of pros successfully using mid-range models like the Canon EOS 7D and Nikon D300S in such conditions. But there are also a few less costly DSLRs with good weather-sealing. Pentax touts their current DSLRs (except the K-500) as being "weather-resistant," and one staff member has successfully used his K-5 in the rain numerous times (with the DA* 300mm ƒ/4 SDM lens, which is also marketed as weather-resistant). The Sony SLT-A99 and SLT-A77, Olympus E-5 and Sigma SD1 Merrill also incorporate weather-sealing measures. It's wise to protect even "weather-sealed" cameras from rain as much as possible, and bear in mind that many DSLR lenses aren't weather-sealed.

Today's entry-level models generally have shutters tested to around 100,000 activations (Canon EOS 6D, 70D and 60D, Nikon's current DSLRs from the D5200 down) or don't have shutter-cycle ratings. Sigma's SD1 Merrill pro DSLR features a rugged body, but with a 100,000-cycle shutter.

Pro DSLRs also have more rugged shutters. The all-out pro Canon EOS-1D X and Nikon D4 have been tested to 400,000 cycles. Mid-range models have staunch, but less hardy shutters: Nikon's D800/D800E and Sony's SLT-A99 have shutters tested to 200,000 cycles; 150,000-cycle shutters are found in Canon's EOS 7D and 5D Mark III, Nikon's D600, D300S, D7100 and D7000, Olympus' E-5 and Sony's SLT-A77.

The takeaway here is that higher-end DSLRs will work longer in harsher conditions than lower-end ones, and pro models are the most rugged.

Does Full Frame Give You Less Depth Of Field?

If you shoot at the same shutter speed and aperture with a full-frame DSLR and an APS-C model, from the same distance, and use a focal length on each camera that results in the same framing, the full-frame image will have less depth of field. If you want to have the same depth of field in the full-frame shot, you'll have to close the lens down 1.3 stops, which, in turn, means you'll have to use a longer shutter speed to keep the same amount of light striking the sensor (if lengthening the exposure time won't result in blur due to camera shake or subject motion). If you increase the ISO to maintain the same shutter speed with the aperture stopped down 1.3 stops instead, less light will fall on the sensor and image noise will increase.

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