Here’s an interesting article courtesy of the New York Times Online - entitled A Camera That Frees Your Face - the brief article is sort of a mini-review of Sony’s A300 DSLR, but what’s interesting about the article is the discussion on how Sony designed the Live View system.
Actually, a few recent S.L.R. models do, in fact, have this Live View feature, but it’s mostly a disaster. It works by flipping that mirror up out of the way, so that light from the lens hits the image sensor, which feeds the image to the screen. Trouble is, once the mirror goes up, no light hits the autofocus sensor, so the camera can’t focus.
So here’s what happens when you press the shutter button. There’s a noisy clank as the mirror drops down again; the screen goes black; the camera computes focus and exposure; the mirror lifts again; the screen comes back to life; and finally — a second or so later — the shot is recorded.
In other words, Live View on existing cameras is slow, noisy and deeply confusing. All of this silliness arises because the camera’s image sensor must do double duty: it’s responsible for supplying the screen with a live preview and for recording the shot.
Sony’s technical breakthrough on the A300, therefore, was this: “Duh! Put in another sensor!”
On this camera, turning on Live View sends light from that main mirror onto a second sensor, one that’s devoted solely to feeding the preview screen. The autofocus sensor works normally as you compose a shot, since the mirror never has to flip up.
As a result, Live View is a completely different experience. The camera focuses quickly as you aim the lens, without ever blacking out the screen. When you press the shutter, the screen doesn’t go on-off-on, there’s no loud clacking, and there’s no baffling exhibition of mirror calisthenics inside the camera.
And he does make a nice point too - while most so-called purists and other experts may dismiss the Live View features of DSLRs as mere gimmicks, I think they are extremely useful. Sure, the best way to frame a photo is still holding the viewfinder to your eye, but there are always numerous occasions where Live View on a flip-out LCD is extremely useful. Why lie down in the dirt when trying to frame a flower on the ground when you can just sit and use the LCD to frame for example?
The article is written by David Pogue, owner of Pouge Press, the publisher of the Missing Manual series of books. One of which - Photoshop Elements 6: The Missing Manual is I think one of the better books currently available for Photoshop Elements. If you haven’t already, you can click here to read the rest of the article.
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