The Sony α33 (SLT-A33) was introduced in 2010 together with the Sony α55. Both cameras look like some of Sony's preceeding Alpha-System DSLR models, but inside is a decisive difference: The α33 is not a DSLR anymore because it doesn't use the mirror anymore as part of the viewfinder. Instead the camera's mirror is in fixed position. It is half-transparent ("translucent"), so that only 2/3 of the incoming light reaches the image sensor. 1/3 of the light is redirected by the mirror onto the phase detection autofocus CCD sensor. Thus the camera allows faster imaging action than the preceeding DSLR models of the same quality class. 7 still images per second are possible since there's that extra AF sensor and no more mechanical mirror action.
Being integral part of the Sony Alpha system camera series the α33 also has the Minolta AF lens mount. Thus a big variety of system lenses can be applied with the camera.
And what's so exciting about it? Despite of the redefinition of the camera's mirror's role it has got a viewfinder, but an electronic one with an ocular to look onto a 1.1 Megapixel miniature color display. Another tiltable display in the back shows 1.4 Megapixel image previews or the menues. The camera has an APS-size "EXMOR" (enhanced dynamics) CMOS image sensor which delivers 14.2 Megapixel images. The manufacturer calls the new camera type "SLT" (single lens translucent).
- α33/α55 operating system Linux, sources on Sony-site