I see some odd comments on dPreview forum including one guy attacking me on the basis this post is 'bitter' towards Sony. I'll admit to writing a title for the post which might attract readers
To set the record straight, I have never been invited to ANY Sony international launch since the Alpha 100 in 2006, which had a much larger guest list than any subsequent rollout including many freelances and smaller specialist journal editors like me. I attended the Croatian NEX launch as a representative of the British Journal of Photography, and before that the Alpha 900 launch held 40 miles away from home in Scotland (I was not invited, I asked to be allowed to attend the press conference without taking part in any of the press 'activities' and they agreed). Also, no other company has invited me to any international launch this year or last; in fact, they have all been very tight on the guest lists and even on launches since the last economic crisis. Nikon do fairly simple London events for the UK press, Canon tends to invite journalists in for a half-day briefing one by one (which I have to say is the best approach).
Nor has any other camera maker provided pre-production or even early test samples to me, directly - only to the British Journal, where I remain one of the three or four specialist review writers, my main responsibility being 35mm-style professional DSLRs (other writers handle medium format, rangefinder-style, compacts, etc).
I don't like being accused of writing articles like this out of 'bitterness' on dPreview forums where it's very well known I can not reply, especially when the followups contain misleading technical comments like 'chromatic aberration' being caused by semisilvered mirrors. That is something I have never mentioned as it doesn't happen.
To clarify, a 45° (or similar) beam-splitter prism has a strong polarizing effect, and the polarization strength depends on the angle of incidence of the image-forming ray. This is why circular, not linear, polarizers have been necessary even before the use of semisilvered mirrors in SLR AF systems, beamsplitter based focusing screen spot metering systems being one example. A full mirror has no polarizing effect. A semisilvered or pellicle mirror will have an effect depending on its strength, its angle, and no doubt other factors only the optical manufacturer will be able to control.
Some day I may try to prepare an article on the issues of polarization, viewfinders, AF systems, metering systems and the performance of sensors. Using a linear polarizer, I have checked whether or not the cover glass of camera sensors (or surface of sensor itself) shows evidence of polarized reflection as expected, and of course it does - I can only check this on medium format sensors, as I do not have an APS-C assembly removed from the camera. I have often felt that from some DSLRs, under some conditions with wider angle lenses, I was almost getting a polarized sky without using a filter and indeed that would seem to be happening - a weak effect, but present.
The use of any kind of SLT mirror, beamsplitter etc whether reflecting or transmitting will also have a similar weak effect on polarization but its 'angle' is across the short side of the image frame and when the camera is held normally, any polarizing effect would tend to affect the ground not the sky.
David
Though there is a fine line how far one can go and I trust you have more journalistic experience in that than me. What bothers me sometimes when titless are misleading, like when on a french website they would say '25 killed in horrible plane crash in Paris'. Then you click and learn it's not Paris in France but a small village never heard of, that the crash was 15 years ago and that the pilot survived and he crashed into a farm killing 25 chicken 