The design also replaces the optical viewfinder present in conventional DSLR with a high-resolution electronic viewfinder. The translucent mirror is fixed in position so does not have to flip up to take a still image, enabling rapid continuous shots of up to 10 frames per second. The static mirror also eliminates "mirror slap", the noise produced by the movement of the mirror during a shutter actuation, making the A55 quieter than standard DSLRs.
The A55 is one of the first four Sony Alpha DSLR / SLT cameras with video mode included, capable of 1080i. It is also capable of shooting 1080p at 30fps. The SLT design means that it is capable of using phase-detection autofocus during video recording. It has body-integrated image stabilization, and a 16.2 MPx APS-CCMOS sensor.