So, as the rumor mills asserted, Sony has released four new interchangeable lens cameras with DX sensors, two of them DSLRs and the other two pellicle cameras designed to look like DSLRs. The new DSLRs are essentially very similar to Sony’s previous generation DSLRs (with the weird hybrid focusing trick for live view) while the pellicle cameras are actually very interesting. The new SLTA55 is already reviewed in depth at dpreview, so check that out. (The reviewers were unable to process the RAW images as of writing this so we won’t know just how good the low light/high ISO performance is with RAW, but just based on the JPEGs it looks like Sony has finally shaken off its IQ issues (i.e. the excellent performance of the NEX cameras was not a fluke).
Sony’s new pellicle cameras offer continuous live view (because the sensor is always getting 70% of the incoming light) and continuous phase-shift autofocus (i.e. DSLR-quality/speed autofocus) because the autofocus sensors are always getting 30% of the incoming light. It also means you don’t get an optical viewfinder, but instead get a 1.4MP EVF (which is better in some ways than an optical finder, and worse in others). If the new cameras have one significant weakness, it is that their continuous shooting seems somewhat compromised (essentially the live view — which is the only view — seizes up during 6fps or 10fps continuous shooting, and in 10fps mode you have no control over exposure).
And I should add that Sony has managed to seriously reduce the new cameras’ dimensions without significantly impacting usability. (Indeed, the Sony bodies are barely larger and heavier than the Panasonic G2, which is remarkable given the design constraints.)
So, to summarize, these cameras clean the Panasonic G/GH series clocks (especially since they have sensor-shift image stabilization), and give conventional DSLRs a run for their money as still cameras. If it weren’t for the new cameras’ continuous shooting compromises I would find them almost irresistible.
And the Nikon D3100‘s reign as the only DSLR-class camera capable of shooting 1080p video while continuing to autofocus was not only very short-lived (i.e. about two days) but pretty much thoroughly outclassed (given how much better phase-shift autofocus tends to be than contrast-detect).
Addendum
I took two photos from dpreview and scaled them so their lens mounts matched and here’s the result. The a33 is markedly smaller than the a560, despite sharing the same sensor and image-processing pipeline (and being announced on the same day) so this is the immediate size-saving Sony obtained by ditching the conventional SLR mirror. That’s pretty amazing.
Note that the new “conventional” DSLRs from Sony offer better continuous shooting (7fps with an optical viewfinder) but lack the focus-while-filming video (they still offer 1080p). If you recall, Sony’s “conventional” DSLRs are already pretty radical, having a bunch of wacky design tradeoffs (a smaller, dimmer optical viewfinder) in exchange for faster phase-change autofocus in live view. I’d have liked to see more differentiation between the new pellicle cameras (which I see as compromising still shooting in favor of video) and the “conventional” DSLRs, but perhaps we’ll be seeing a refresh of the a850 along those lines (and, after all, at $1950 the existing a850 is a serious bargain, assuming you’re willing to hunt for second-hand lenses or wait and hope for Sony to release more).
Even More
Interesting criticism of the a55 (et al) here, mostly along the lines that video capabilities (1080i, low bitrate, and no manual controls) in the new cameras is seriously (and intentionally) crippled. Steadishot makes the camera overheat after 9 minutes. The AF only works when the aperture is wide-open, video bitrates are no better than compacts. I have to say I find interlaced HD video to be actively offensive (it’s a holdover from analog and has no place in a modern pipeline).
And more technical criticisms here, along the lines that marketing futzed with the specs, the onboard computer hardware is laggy in general and specifically the way the camera seizes up after shooting (if image review is switched on) is a major bummer. These are finicky, but not minor criticisms, since one of the two main reasons for using DSLRs over compacts is handling.
There’s also some discussion as to “ghosting” caused by internal reflections in the mirror (which are unavoidable). This kind of thing could be post-processed out of the image (in-camera) since the effect is very consistent but it’s another drawback of the fundamental design. (And it’s quite noticeable in some of the examples in the thread.)