Wait, what? When Sony first introduced its SLT series of A-mount cameras sporting a translucent mirror, the whole idea was–or so we thought–that the mirror wouldn’t have to flip up because, you know, it being translucent and all. But now it seems that Sony decided combining classical SLR flip-up mirror tech with a translucent mirror would be an even better idea. And we actually have to agree.
The problem with the SLT technology is, that the mirror isn’t actually tranclucent, but only semi-translucent. That means that part of the incoming light gets deflected towards the AF sensor, while the majority passes through the mirror and hits the sensor. The technology is pretty clever because it allows for permanent live-view while providing phase-detection AF at the same time, but whith it comes a slight loss of light because the semi-translucent mirror is fixed in position and doesn’t flip up during exposure like that of a regular DSLR.
With a semi-translucent mirror that actually flips up during the exposure, Sony could solve the light-loss problem, and still have phase-detection AF and live-view at the same time. Realistically, though, Sony probably won’t ever put this technology into one of its A-mount cameras, and the reason for that is fairly simple: they already have sensors that sporting phase-detection pixels, namely those of the A7 and A6000 E-mount cameras.
So instead of further developing its SLT technology, our bet is that in its next generation of A-mount cameras, Sony will dump the mirror once and for all, and instead rely on its on-sensor phase-detection AF. Technically, this would mean that all future A-mount cameras would essentially become mirrorless, but with a much longer flange-back distance compared to the E-mount system, and with a more traditional DSLR look compared to the styling of the majority of Sony’s E-mount cameras.
As always, this is just speculation at this point and to be taken with a grain of salt. However, the way Sony has been innovating lately, the above scenario seems rather probably to us.