Many Sony DSLRs use what is called a “pellicle mirror” to show the image in the viewfinder.  In contrast to a traditional DSLR mirror that is opaque, the pellicle mirror allows most of the light to go to the sensor while using some of the light to produce the electronic viewfinder image.  This technology is new to popular DSLRs, but it has been used in cameras for years.

There are many advantages to using this technology in Sony DSLRs, and one of them is full-time autofocus for video.  It also means that the viewfinder doesn't go dark when a picture is taken.  Unfortunately, it also means that some of the light that could be sent to the sensor is soaked up in the mirror.  You know what that means… worse low light performance.  Sony claims to overcome this limitation with advanced noise reduction, but it always makes me think how good the camera could be if it used all of the light.  Low light performance is the number one most important feature that I look for in a DSLR.

I have been asking for this feature for years and I'm so glad to see that Sony has put this feature in the Sony a77 DSLR.  I love shooting in aperture priority mode whenever I can, but I have to keep watching my shutter speed so that it doesn't dip too low for shooting in the evening when the light is fading fast.  Imagine if I could set my aperture and shutter speed, and then know that the ISO will automatically increase to allow for proper exposure up to a certain level where I know that the camera won't produce too much noise.  Very useful for wildlife and sports photographers.

When you see the specs of Sony DSLRs, nothing will impress you more than the frame rates.  It is truly remarkable.  For example, the Sony a77 can capture 12 frames per second of 24 megapixel images.  While I certainly want to use that every day, it would be INCREDIBLE for shooting sports, wildlife, or kids.  I better stop writing about 12 frames per second before I can't hold myself back from Amazon.com.  It's begging me to buy one just for the times when I neeeeeed that kind of speed.

Whereas Canon and Nikon have placed the image stabilization/vibration reduction feature inside each lens, Sony puts the image stabilization mechanism in the camera itself.  While I have not seen any head-to-head comparisons of the two approaches to say which performs better, most people say that this is an advantage for Sony.  Having the mechanism in the camera means you do not have to pay to have the technology put in each and every lens, which is a nice feature.