It looks like someone has done some detailed testing to show that the translucent mirror in the Alpha cameras does indeed NEGATIVELY impact image quality. The NEX-7 should have better image quality than the A77 since the NEX cameras don't use the translucent mirror (assuming you aren't using that new adapter with the translucent mirror built in). http://thesybersite.com/sony/a55/index.htm#slt_mirror_image_quality
Not convinced. The test was done on the A55 not the A77 and since the A77 is one generation on it is reasonable to expect that the technology has matured. We'll have to wait and see.
Fair enough, but I highly doubt we'll see much of a difference in terms of how the A77 handles the translucent mirror vs how the A55 handles it. It all boils down to physics in the end ... part of the light hitting the translucent mirror has to bounce up to the AF sensor and part of the light has to pass through ... meaning there isn't an uninterrupted path for light to hit the sensor. Olympus dealt with somewhat similar issues with the translucent prism technology they used in the E-10 and E-20 fixed lens DSLRs. Hopefully the A77 will suffer less in terms of image quality problems, but it's safe to say there will still be some visible difference between an A77 shot with and without the translucent mirror ... which is why the NEX-7 will potentially have better image quality (though the fact they cameras use different lenses may also image image quality).
