Unique Features of the Sony Alpha A55
The Sony Alpha A55 has a long list of features – some of which you may find in a few other cameras and others that are unique only to the A55. But taken together they they make the A55 a very compelling piece of equipment.
In Part 1, I talked about the “standard” features of the A55.
In this part of the review, I’ll key in on several of these features that are both unique and innovative.
The first three features are possible because of the A55’s translucent mirror.
Electronic Viewfinder
| The first time I used the A55, I was surprised when I put my eye up to the viewfinder. In place of a conventional reflex viewfinder used in DSLRs, the A55 has an electronic viewfinder (EVF). The resulting image is somewhat similar to what I might see on a miniature television.
A big advantage is that the image in the EVF can be overlaid with a variety of information as you can see below. |
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| Having used a dozen or more DLSRs extensively, it took me about a week to get used to the EVF. As a wearer of eyeglasses I was able to set the built-in diopter adjustment correctly for my vision. The image is bright and clear owing to the 1.1 megapixel viewfinder screen, a high refresh rate (60fps). The EVF also has 100% field coverage. I especially like the level gauge that helps to align the horizon. | ||
High Speed 10 frames per second capture
| Certainly one of the features that Sony has stressed in their promotional literature is the A55’s ability to capture action with a high speed frame rate. Freed from a mechanical reflex assembly, the A55’s shutter mechanism becomes simpler and faster.
In fact, the mode dial has a specific selection for high speed capture. Sony rates this as 10 frames per second. |
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| In this series of photos of a landing Southwest 737 aircraft, I pressed the shutter for about three seconds, panned as the aircraft approached and captured a total of thirty-one photos with the camera set to record JPG images only (not RAW). | ||||
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| During this time, the EVF continued to follow the aircraft as I panned. However, as soon as I removed my finger from the shutter, the viewfinder went black and the A55 was essentially locked for about 30 seconds while the images were written to the SDHD card. | ||||
Full-time auto focus
| Another feature made possible by the translucent mirror is full-time autofocus. Without a reflex mirror that has to flip out of the image path, the autofocus mechanism in the A55’s electronic viewfinder continues to operate uninterrupted.
Additionally, the A55 autofocus system uses phase detection and generally operates faster than contrast measurement. The result is that the autofocus is available 100% of the time for both still and video captures. Here is a sample video that shows that the autofocus works well for both movements of the subject and changes in the focal length of the lens. |
| Keep in mind that the autofocus mechanism uses a small motor the drive the lens. Unfortunately, the built-in microphone has also recorded the sound of the focusing motor. One way to avoid this unwanted noise is to use an external microphone when shooting video. |
Articulating (moving) LCD
| The A55 has an excellent LCD. It’s a high resolution display with 920K pixels. The LCD itself has sensors which automatically adjust the display on the LCD based on ambient light levels. The specs call attention to the Sony’s TruBlack technology which improve the contrast and visibility. I won’t vouch for this TruBlack directly, but I can say that the display is bright and very sharp and like the EVF also has 100% field coverage.
The LCD is mounted on a unique hinge which allows it to tilt 180 degrees vertically and 270 degrees horizontally. |
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| As you turn the camera from a horizontal to a vertical orientation, the LCD also turns to match the camera. I’ve found it especially useful for taking low-angle photos without having to lay on the ground. | ||
Built-in GPS
| The A55 has a GPS receiver that can automatically location tag an image as it is captured. Although the A55 isn’t the first camera to include a built-in GPS feature, it’s the first one that I’ve used. | |
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This photo of a big horned sheep was automatically tagged with the geographic coordinates within Zion National Park by the A55.
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| The GPS recording works well when shooting outdoors where the camera is able to receive the satellite signals. When shooting indoors where the camera may not be able to receive the GPS signals, the images may be incorrectly tagged with the last known location. | |
The A55 has several more impressive features that we cover in Part 3.
Written by Arnie Lee
