Sony SLT-A55 and SLT-A33
When they were introduced in 2010 the Sony SLT-A55 and SLT-A33 translucent mirror cameras, captured the attention of many people in the photography world.
As a true hybrid camera that broke the mold of traditional DSLR design the Sony SLT-A55 brought translucent mirror technology to the world of digital technology in a new and exciting way and were heralded as one of the technological breakthroughs of the year by several magazines and organizations.
While the idea of using a translucent or “pellicle” type of mirror is not new, Sony’s implementation of it along with full-time phase detection autofocus even when shooting HD movies is significant enough that Time Magazine named these cameras to their “50 Best Inventions of 2010” list.
Rather than sticking with the conventional DSLR design of a moveable mirror assembly or eliminating the mirror completely Sony decided on a bold new approach with the implementation of a fixed translucent mirror that in many ways offers the best of both worlds.
Named by Popular Photography as their 2010 Camera of the Year the Sony SLT-A55 and SLT-A33 gave birth to a new type of hybrid camera known as the “SLT” or Single-Lens Translucent Camera. While generally considered to be in the same category as a DSLR (digital single lens reflex camera) the fact that these cameras do not have an optical viewfinder really makes them a separate type of camera.
DSLR’s by design use a moveable mirror that reflects light to an optical viewfinder. Because the Sony SLT-A55 and SLT-A33 have a fixed mirror and an electronic viewfinder they cannot truly be classified as a DSLR even though they are very similar in many other areas.
By using a fixed semi-translucent mirror Sony was able to release a DSLR type of camera that uses a faster phase-detection autofocus system instead of the more common but slower contrast-detection autofocus when filming video or using the live view feature. This allows the Sony SLT-A55 to capture up to10 frames per second, which had been unheard of in a camera of this price range.
By thinking outside the box and implementing the translucent mirror design, Sony’s engineers were able to create a DSLR-like camera specifically built for live view and video recording. The new design allowed them to incorporate the faster phase-detection autofocus even when the camera was in live view mode or recording HD video.
Unlike micro four thirds and mirrorless interchangeable lens cameras which have no mirror assembly, Sony’s new hybrid SLT Alpha models are designed around a fixed translucent mirror that allows about 70% of the light to pass through to image sensor while reflecting some to the newly designed 15 point phase detect autofocus system. This results in a camera slightly smaller than a typical consumer DSLR but not as small as some of the MILC (mirrorless interchangeable lens cameras) such as the Sony NEX-5.
Features of the Sony SLT-A55 and SLT-A33
- The Sony SLT-A55 uses a 16.2 megapixel APS-C, CMOS image sensor while the SLT-A33 uses a lower resolution 14 megapixel APS-C, CMOS sensor.
- An ISO range of 100 to 12,800
- 15 point full time phase-detection autofocus system
- Electronic viewfinder with 100% field of view
- Built-in GPS in the US model SLT-A55V
- Electronic level displayed in the EVF/LCD with pitch/roll indicator. This is a useful feature in helping the photographer keep the horizon level, which is a important part of good photo composition.
- Up to 10fps continuous shooting rate for the SLT-A55
- Able to capture HD movies with phase detection autofocus.
- An articulated 3 inch 'TruBlack' LCD that can tilt 180 degress vertically and rotate 270 degrees. The LCD display also has a “Sunny Weather” mode designed to allow it to be usable in direct sunlight.
- Dual memory card support so the cameras can use either Memory Stick or SD memory cards.
- The Sony's Alpha SLT cameras use the same A-mount lenses as do other Sony Alpha DSLR’s and older Minolta auto focus SLR’s.
- Handheld twilight mode and HDR mode. In the Auto High Dynamic Range mode the camera captures several images of different exposure and automatically combines them into one HDR image. In Handheld Twilight mode multiple images are captured and automatically combined to help reduce camera shake.
Camera Controls and Other Important Information
The controls of the Alpha SLT-A55 look similar to other Sony cameras.
It features a top mounted mode control dial with the usual camera mode settings including: program mode, aperture mode, shutter mode, manual mode, a special 10 fps burst mode, sweep panoramic mode, scene mode, no flash mode, automatic mode and an intelligent auto mode which allows the camera to select which “scene” mode should work best for that particular instance. I have found that these type of “intelligent scene modes” generally work well as the camera “figures out” what the best mode is for the type of scene you are photographing.
The camera’s high resolution electronic viewfinder has a 2X magnification feature that allows the user to see a magnified image of the scene in order to give them more precise control when manually focusing.
Limitations of the Live-view System and High Speed Burst Modes
One of the drawbacks of the live view system is that there can be close to a two second delay before the image is displayed when the image review feature is turned on. During this time you cannot go back to live-view mode so this is something to keep in mind when reviewing your images.
Shooting at the highest 10 frame per second burst rate requires the Sony SLT-A55 be in the dedicated 10 frame per second burst mode. In this mode the exposure is automatic. For the photographer who wishes to have full control over the camera settings there are also 6 and 3 frame per second modes that will work in any of the normal camera modes.
When shooting in the high speed modes with the Sony SLT-A55 it can take almost a minute for the camera to write the images to memory after you stop shooting. Even with a fast memory card it can easily take up to 50 seconds after you release the shutter button for the camera to finish saving the photos to the memory card and be ready to take more pictures or view the ones you just captured.
Another drawback of the higher speed modes is that at 6 fps and 10 fps the camera's live-view system cannot keep up. This can make it harder to pan as you cannot always accurately tell where the subject is. Instead of seeing a live image in these high speed mode you end up with a slide-show of still images which in some circumstances can be confusing when trying to follow a moving subject while panning. As with most EVF cameras there can be some noticeable lag when panning a fast moving subject. That is why in general I still prefer optical viewfinders over the EVF type on the Sony SLT-A55. Although with time I would likely adjust to using a electronic viewfinder when panning to follow a fast using subject so this is not a deal breaker when one considers all this camera offers for the money.
Even with these limitations the hight speed burst capabilities of the Sony SLT-A55 Alpha are in a class of their own for a camera in this price range. In order to have a DSLR type of camera that can capture photos at 10 frames per second you normally have to move into the professional type DSLR which cost several thousand dollars.
The bottom line…
The Sony SLT-A55 and SLT-A33 are exciting cameras that would well suit most photographers. With their full time phase-detection auto focus and live view mode they offer a great value in their price range. Sony has done a remarkable job in the design and implementation of the translucent mirror technology and the SLT models should be top consideration for anyone looking for a camera in this price range.
While the translucent mirror design results in faster autofocus, especially when filming video, as well as a faster burst speed and smaller camera size it is not without its drawbacks.
Because only 70% of the light makes it through the translucent mirror to the image sensor, more light is needed in low light situations to properly expose the image. Therefore you will likely have to use a slower shutter speed or larger aperture than you would for a DLSR under the same light conditions.
One place the Sony SLT cameras come up a bit short is in battery life. Powered by an infoLITHIUM battery the SLT-A55V is rated at up to 380 photos per charge and the SLT-A33 is slightly less with up to 340 photos per charge. Serious shooters will need to add extra batteries to make it through a full day of fast paced shooting.
As the 2010 Popular Photography Camera of the Year, the Sony SLT-A55 offers an impressive value and raises the bar on the performance standards and features for this type of mid-level consumer camera.
With its unrivaled speed and 10 fps burst mode it is a good affordable camera for soccer moms and baseball dads. Affordable priced and full of features these cameras certainly deserve the acclaim they have received since being introduced.
Sony Alpha SLT-A55 Videos