Now Sony had prepared two more Alpha DSLR bodies, Alpha A300 and Alpha A350. As you can probably assume based on the new model markings, they are meant to be positioned in some middle class, between flagship A700 and entry-level A200.
In brief, Alpha A300 is totally same camera as the A200 with addition of live preview option and swivel LCD screen. While new Alpha A350 have new optical sensor with 14.2 megapiksels.
Main improvements that Sony demonstrates on new A300 and A350 cameras is the Quick AF Live View System. Sony did manage to solve the big problem, that all other DSLR manufacturers have struct while trying to build DSLR with live preview options, the lack of auto focus and light metering.
Primary the solution is based on installing another small optical sensor, witch will be used only to produce live image on the LCD screen. This kind of a solution is not new, its already seen on the Olympus E330. I will just remind you that Olympus E330 was the first DSLR camera in the world that have live-preview option. E330 was not a market success but it will be remembered as a first stone who triggers the avalanche. Today two years after the Olympus E330 presentation, you cant hardly find DSLR without some kind of live preview.
As I was saying the heart of Sony Quick AF Live View System solution is additional little optical sensor witch is positioned in viewfinder. So when the live-preview button is pushed, little mirror, that we usually look at when you look at the viewfinder, raise and redirect light to that additional sensor.
Other manufacturers have different approach for creating live-preview, they are using big camera sensor to produce live LCD image, to archive that they have to raise the main mirror. When the mirror is raised, it is not possible to do the auto-focusing or light-metering. So those manufacturers has find different ways to overcome this, such as focus based on color or contrast, they are using main camera sensor to focus the camera. Sony’s solution doesn’t have such demands because, big mirror is on the same place like when you are looking at the viewfinder.
This system have other side-effects, currently there are no sufficient information about that, but the possible problems can be that viewfinder is covering only about %95 of the image, so the live image on display will not fit the actual photo. Other problem is related to depth of field, as the live preview sensor is much smaller then the main optical sensor, live-preview image on the LCD will result with much bigger depth of field that won’t be even close to the photos taken DOF.
Nevertheless, this kind of live-preview has much more use in real world in combination with large swivel LCD. So now you can take pictures while you dslr camera is over your head or on you hip.
Sony’s DSLR lineup now counts for different camera bodes, they are remakably similar, there are only few details that differs them.