Sony A55 vs A57
The A55 and A57 are a departure from the two common camera types, the SLR and the compact. Sony calls these cameras SLTs, or Single Lens Translucent, because it uses a semi-reflective mirror that stays in place instead of moving up and down like in traditional SLRs. The most obvious difference between the Sony A55 and A57 is their size. The A57 is considerably bigger in all dimensions than the A55 and weighs roughly 40 percent more. This makes the A57 look more like a DSLR camera, which is what it is competing with.
In terms of features, the A57 also has a number of improvements over the A55. One difference between the A55 and A57 is in video recording. Both cameras are capable of recording 1080p videos, but only the A57 is capable of 1080p60 or at 60 frames per second. The A55 is only capable of producing 30 frames per second at this resolution. To reach 60 frames, the camera interlaces the two successive frames to produce an intermediate frame, doubling the frame rate to 60. This is called 1080i. Of course, there is some loss in video quality especially when viewed through new 120Hz TVs.
Another feature that is only present in the A57 is WB (White Balance) bracketing. WB bracketing is used when the image you are taking has a very high contrast; for example, a shaded area with very bright light around it. With the A55, the image you take will either have overexposed bright areas or loss of detail in the shaded area. With WB bracketing in the A57, multiple images at different exposure levels are taken and merged together to get the best exposure in all parts.
But there is also a feature in the A55 that is lost in the A57. The latter doesn’t have a GPS receiver. A GPS receiver is useful for encoding location as well as orientation information onto the images. This information is not visible on the image but can be extracted by special software. Using the GPS module can help you organize your photos by locations which is helpful if you travel a lot.
Summary:
- The A57 is bigger and heavier than the A55.
- The A57 can record videos at 1080p while the A55 can only record videos at 1080i.
- The A57 is capable of WB Bracketing while the A55 is not.
- The A55 has a built-in GPS receiver while the A57 does not.