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Tuesday, October 2, 2012

Hi-Tech Studio: High-Speed Still Photography With SLTs

Sony’s Translucent Mirror Technology makes high-speed shooting with phase-detection AF affordable


This Article Features Photo Zoom
Translucent Mirror Technology provides some advantages when shooting at high speeds.


The notion of hybrid cameras and hybrid shooting wherein you're capturing full-resolution still frames at 24, 30 or 60 fps is a hot topic for professional photography.
We've devoted a fair number of pages to it in DPP over the past couple of years, and we'll continue to do so as the technology improves and becomes ever more accessible to more photographers. In short, it's the notion of rolling instead of snapping. RED cameras and the RED DSMC (Digital Still & Motion Camera) concept that the company has stated would be an overarching philosophy for their cameras moving forward are currently the leaders in this sort of hybrid workflow. RED has achieved the DSMC model from the full-motion side with impressive results.

From the traditional still camera side, we're closing in on the same goal of continuous high-speed shooting. Not everyone can afford a camera like the RED Epic, but today there are a number of HDSLRs that can shoot full-resolution still images (24 megapixels, in some cases) at very high speed. For example, Canon's EOS-1D X can shoot 18.1-megapixel images at 12 fps with AF for each shot (14 fps with focus locked and JPEG only), and Nikon's D4 can shoot 16.2-megapixel images at 10 fps (11 fps with focus locked).

Translucent Mirror Cameras
In this article, we're focusing on the unique technology of the Sony translucent mirror cameras, which offer a high-speed option that maintains autofocus throughout the shooting burst. Most DSLRs momentarily lose AF contact with the subject because the mirror has to flip out of the way as the exposure is made. The translucent mirror Sony models don't have this characteristic. The AF system stays locked on because the fixed mirror provides the AF sensor with a continuous "view" of the subject.

The new full-frame Sony SLT-A99 can shoot full-res images at 6 fps (fast for a 24-megapixel full-frame camera with phase-detection AF for each shot (7 fps in cropped APS-C mode) and 10 fps in Tele-zoom Continuous Priority AE mode. The A99 also adds a new twist to the TMT story: In addition to the normal 19-point phase-detection AF system, there are 102 phase-detection sensors on the image sensor itself. This produces a much wider AF area, greatly improving tracking of subjects moving across the frame and against busy backgrounds.

The other Sony SLT cameras also give you some affordable options. The 24.3-megapixel SLT-A77 and A65 list for $1,399 and $899, respectively, and the 16.1-megapixel SLT-A57 lists for $699. Yet the A77 and A65 can shoot full-resolution, 24.3-megapixel images at 12 fps and 10 fps, respectively (at the lens' widest aperture; 8 fps at any aperture) with quick phase-detection AF for each frame. The A57 can shoot 16.1-megapixel images at 10 fps and cropped 1.4X images at 12 fps, again with AF for each frame.

 

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