Monday, August 23, 2010

Sony introduces its first DSLRs with 1080p/i video

Sony has just introduced four new cameras, two DSLRs (A560 and A580), and two quasi-DSLRs (A33 and A55). Their video specifications are very similar; all four cameras can do 1920 x 1080 1080i at 50/60fps with AVCHD compression (at 17Mbps average), and 1440 x 1080 1080p using MPEG-4 compression (at 12 Mbps average). So what, you ask, is a quasi-DSLR? Sony's new design uses a permanent, highly light-transmissive fixed mirror than enables continuous autofocus and live mode for both still shots and video. This means that the cameras have electronic, not optical, viewfinders, although they have a largely conventional DSLR body and can use Sony's conventional Alpha-range lenses. The A560 and A580 are conventional DSLRs and can't do continuous video autofocusing.

Digital Photography Review has published a review of the first production version of the A55. There are some unusual "features" that it found in its video tests:
  • The camera can record approximately 29 minutes of video in AVCHD mode, but it can only record 9 minutes if SteadyShot is turned on. The review is unclear as to why image stabilization affects storage capacity so much, but it may be due to the fact that the camera does digital image stabilization inside the camera rather than using lenses with optical image stabilization.
  • Even though MP4 uses a lower bitrate and should allow a storage card to save more video, storage of MP4 files is limited to 2GB at a time, which limits the maximum duration of a shot to around three minutes. AVCHD doesn't have this limitation and can span multiple files in a single shot.
  • DP Review found that the A55's autofocus feature was often less than helpful in video mode, as the camera sometimes lost track of the object that it was focusing on and went out of focus. This problem was especially pronounced with fast-moving sports events.
  • They found that the A55 has a fairly pronounced rolling shutter "jello" problem, about the same as many other DSLRs, but more severe than some competitors.
  • The review states that the A55's average AVCHD bitrate is 17Mbps, but it's unclear if that's the camera's maximum bitrate. Some other DSLRs and camcorders can support 24 to 30 Mbps.
DP Review was very impressed with the A55 as a still camera, and in fact gave it a Gold Award, so it's important to recognize that it's a very good camera. However, as with many DSLRs, the video functionality of the A55 isn't as well implemented as the still image features. In the U.S., the A55 will ship in October at a list price of $750 (body only) and $850 (with an 18-55mm lens). The A33, which has essentially the same video specifications as the A55, will ship in September priced $100 lower than the A55.
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