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Sony Alpha 35 Tested in DxOMark Lab

August 6 2011

by Philip Northeast

The main features of the new Sony Alpha 35 SLT camera are a significant reduction in power consumption and a new 16 megapixel sensor.

The Alpha 35 is an upgrade of the Alpha 33, only released in October last year. The main criticisms of the Alpha 33 related to its high power consumption and the related overheating of the digital sensor.

The Alpha 35 uses the same battery as its predecessor and the DxOMark test show only a small improvement in photo quality performance. This suggests the likely reason for the new sensor is more efficiency, so it uses less power and consequently generates less heat.

Sony SLT-A35

The Alpha 35 slots into the price range of entry level Digital SLR  cameras. It has the same 16 megapixel APS-C sensor as Pentax and Nikon use in higher spec DSLRs, but the overall performance in this camera is similar to two leading entry level Digital SLRs according to DxOMark lab tests.

Translucent Mirror System

The Sony SLT-Alpha 35 is an SLT not a DSLR.  That is a Single Lens Translucent camera as it does not have a moving mirror for an optical viewfinder.

Inside the Sony SLT-A35 and the translucent mirror

Sony’s translucent mirror assembly takes some of the light to the normal pentaprism area for metering and focusing, but none for the viewfinder.  In the place of the DSLR’s optical viewfinder Sony provide an electronic version, the Live View feed is displayed in the viewfinder. Photographers have the choice of Live View on the rear LCD screen or in the viewfinder.

“Our Translucent Mirror Technology is one of the most significant SLR structural changes in more than a decade,” said Kristen Elder, director of Sony’s digital imaging business group.

Retaining some form of viewfinder allows photographers to hold the camera securely to minimise camera shake using the human tripod technique. Holding the camera properly, in conjunction with Sony’s in camera sensor image stabilisation, helps produce sharp photos.

Using a viewfinder helps photographers while taking movies to reduce the jumpiness often associated with home movies. It also makes it easier to support the camera over the longer periods, as movie takes are usually longer compared to single still photo. This is can be important when using heavier telephoto zoom lenses as they would be almost impossible to hold for any length of time at the normal compact digital camera reach method.

The two electronic displays on the Sony SLT A35

To sweeten the deal for photographers, Sony incorporated the Tele-zoom High Speed Shooting feature that magnifies the centre of the photo area giving about an effective 1.4x magnification.

Focusing and Movie Mode

The main benefit of the translucent mirror approach is the Sony SLT-A35 to use Phase Detection AF for HD movies as well as for normal still photos. It does not matter if the photographer chooses to use the viewfinder or Live View on the LCD.

Digital SLR cameras use the Phase Detect AF system for fast accurate focusing in conjunction  with the optical viewfinder system. For Live View and movie modes most digital cameras, including DSLRs, use the normally slower and less precise Contrast Detection AF system.

This gives the Sony Alpha 35 the ability for fast accurate continuous focus in movie mode.  Ideal for tracking fast moving subjects.

One of the attractions of DSLR cameras for movie shooting is ability to use telephoto lenses that allow video photographers that selective focus effect so useful in story telling.

The disadvantage is the electronic viewfinder or LCD screen use more power than the optical viewfinder in a normal DSLR. The Alpha 35‘s predecessor had a reputation for poor battery life, with a test capacity of only 270 images using the viewfinder and 340 using the LCD screen.

DxOMark Sensor Performance Tests

In the DxOMark Lab the comparison with the older Alpha 33 shows little real difference. The Alpha 35 has less digital noise than the model it replaces showing that this new Sony 16 Megapixel digital sensor is very good in this area of performance.

DxOMark test summary comparison

Looking at the noise performance in more detail the difference between the Sony, Nikon, and Pentax entry level cameras is small. The Pentax Kx has less noise at very high ISO settings, but at more common ISO settings the difference in noise is minimal.

DxOMark noise test

Looking into the detailed results of the DxOMark dynamic range tests reveals that at ISO settings from about 400 and lower the Sony Alpha 35 has an increasing advantage over the Nikon D3100.

Dynamic range is an important measure of the range of light from the brightest white to the darkest black the sensor can record. The implications may not be immediately obvious in a photo but it is the ability to reproduce the subtle range of tones in either the highlights or the shadows. When the sensor runs out of dynamic range these tones are reproduced as all black or all white.

DxOMark dynamic range test

The Sony Alpha 35 has a 16 megapixel sensor compared to the Nikon D3100’s 14 megapixels, and the Pentax Kx with 12 megapixels. The extra megapixels are good for larger photos, but for web use and common size prints the extra resolution is not necessary. One side effect of the extra megapixels is the increased file size places greater demands on memory cards and computer hard drives.

Power Consumption Reduction

According to Sony in their statements to the photographic press, “Reductions in power consumption boost the camera’s battery life to a generous 440 still shots (approx. when using the rear LCD panel) between battery charges – a 30 percent increase over its predecessor.”

This tells only half the story, the power consumption reduction has been more dramatic. Maybe Sony do not want to admit how bad the Alpha 33 was because on the Sony web site the number of still shots using the Tru-Finder™ electronic viewfinder jumps from 270 for the 33 to 440  for the 35 under controlled test procedures.  The actual numbers of photos per battery charge will vary in real life.

With less power consumption any problems with overheating digital sensors are also reduced.

Adorama have spare Sony batteries for the Alpha 35, it is the same battery as the 33 for $US 52.95 and for serious users of these cameras carrying a spare battery is a good idea.


Comparison Specification Summary


Pricing and Availability

The new Sony Alpha 35 interchangeable lens camera will be available this August with an 18-55mm kit zoom lens (model SEL1855) for about $US700.  The Alpha 35  will also be offered as a body-only (without kit lens) for about $US600.



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