Sony Alpha A100 features continued…

Lenses, Super SteadyShot and anti-dust / Screen and menus / Sensor and processing

Any new digital SLR system needs a decent selection of lenses, and by rebranding Minolta’s A-Type mount, the Sony Alpha A100 enjoys a large existing back catalogue of compatible optics. Like other digital SLRs with APS-sized sensors, the A100 effectively multiplies all lens focal lengths by 1.5 times.

Key models from Konica Minolta’s existing lens range have been cosmetically modified with new zoom and focusing rings and rebranded as Sony Alpha. Highlights available at launch, with UK guide prices in brackets, include the DT 18-70mm f3.5~5.6 (£131), AF 75-300mm f4.5~5.6 (£181), DT 18-200mm f3.5~6.3 (£410) and DT 11-18mm f4.5~5.6 £480).

Forthcoming highlights expected during October and November 2006 include the Sony G 70-200mm f2.8 (£1846) and Sony G 300mm f2.8 (£4490), along with three new Carl Zeiss models: the Planar T* 85mm f1.4 (£1048), Planar T* 135mm f1.8 (£1099), and the Vario-Sonnar T* DT 16-80mm f3.5~4.5 (£550).

This last lens, with an equivalent focal range of 24-120mm, sounds to us as the most exciting, (hopefully) delivering a premium general purpose zoom who those who demand higher quality. We will review selected Alpha lenses when they become available. UPDATE: the Carl Zeiss 16-80mm is now delayed until the end of March 2007.

We also contacted both Sigma and Tamron which said existing Minolta AF models should work fine with the Sony DSLR-A100; indeed as compatibility is confirmed, expect them to be rebranded as Sony Alpha products in the future.

Sony AlphaDSLR-A100 bundles

The Sony Alpha A100 is typically sold with two lens bundles: the standard zoom kit includes the DT 18-70mm f3.5~5.6, while the twin zoom kit includes both the 18-70mm and the longer AF 75-300mm f4.5~5.6 – see how this longer lens performs in our Sony 75-300mm review. Since the A100’s sensor crops the field of view by 1.5 times, these lenses deliver 35mm-equivalent focal lengths of 27-105mm and 113-450mm respectively.

It is our policy to test budget digital SLRs with their most common bundled lens options, as they’re normally the ones many owners end up using the most, or at least initially. As such, the optical results on the next page and the gallery examples on the one after are all taken with the Sony DT 18-70mm f3.5~5.6 lens. As mentioned earlier, this is the same 18-70mm lens bundled with the earlier Konica Minolta Dynax / Maxxum 5D, except with a new zoom ring and Sony’s branding.

We look forward to testing other Alpha lenses in the future, in particular the Carl Zeiss models when they’re launched towards the end of the year. In the meantime, the coverage offered by the DT 18-70mm lens can be seen in the examples below compared to the 18-55mm EF-S commonly bundled with Canon digital SLRs.

Below are examples of both lenses zoomed-out to their widest focal lengths, taken from exactly the same position and just moments apart. Both lenses may share the same 18mm wide angle focal length, but deliver slightly different fields of view due to different sensor crop values. The Sony’s crop is 1.5x, giving an equivalent wide angle coverage of 27mm, compared to 29mm on the Canon with its 1.6x crop. A difference of 2mm doesn’t sound like a great deal, but even on the reduced images below, the Sony clearly captures a slightly wider field.

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Sony Alpha DSLR-A100 with DT 18-70mm		Canon EOS-350D with 18-55mm EF-S
18-70mm at 18mm, f8 (27mm equivalent)		18-55mm EF-S at 18mm, f8 (29mm equivalent)

Below are examples of both lenses zoomed all the way in, again taken from exactly the same position and moments apart. Clearly the longer 70mm (105mm equivalent) focal length of the Sony lens allows you to get noticeably closer to distant subjects than the 55mm (88mm equivalent) of the Canon lens. Since most budget digital SLRs are bundled with 18-55mm lenses, this is an advantage the Alpha has over all of them – apart from the earlier Konica Minolta 5D of course.

Sony Alpha DSLR-A100 with DT 18-70mm		Canon EOS-350D with 18-55mm EF-S
18-70mm at 70mm, f8 (105mm equivalent)		18-55mm EF-S at 55mm, f8 (88mm equivalent)

Sony Super SteadyShot

The big selling point of the Sony A100 is it’s built-in ‘Super SteadyShot’ anti camera-shake system. This is based on the Anti-Shake technology developed by Konica Minolta for its 5D and 7D digital SLRs. Like other anti-shake systems, this allows you to handhold much slower exposures than normal, but the technology behind it is completely different.

Unlike other manufacturers which employ optical stabilisation within specific lenses, Super SteadyShot works inside the camera itself. Sony has mounted the A100’s CCD sensor on an adjustable platform where motion detectors analyse any wobbling, and counteract it by momentarily shifting the CCD sensor in the opposite direction.

The platform which houses the sensor is adjusted by fast-reacting piezo-electric actuators, which can shift it by 5mm in any direction. To conserve battery power, Super SteadyShot only kicks in as you take the picture; you can also turn it on or off using a switch on the back of the camera.

Super SteadyShot isn’t just a rebranded technology though: Sony’s improved the system with new gyro sensors which detect low frequency movement and compensate for it sooner. This allows the system to counteract for both slow and fast shake, and Sony now claims an additional half stop improvement over the existing three stops previously offered by Konica Minolta.

Building anti-shake technology into the camera body has pros and cons. On the upside, the benefit can be enjoyed by absolutely any lens you choose to fit, including budget or older models. There’s no need to buy specific (and normally pricier) anti-shake lenses.

On the downside, unlike lens-based optical image stabilisation, you can’t actually see the effect of Sony’s Super SteadyShot through the viewfinder. You just have to accept it’s doing the business behind the scenes, although a five-bar scale in the viewfinder indicates how hard the system is currently working, revealing when it’s close to, or passed its limits of effectiveness.

Sony Alpha DSLR-A100 with DT 18-70mm
Super SteadyShot Off. Exposure 1/8 sec 18-70mm at 35mm, f13 (53mm equivalent)		Super SteadyShot On. Exposure 1/8 sec. 18-70mm at 35mm, f13 (53mm equivalent)

Above are two examples of a bottle taken with and without Super SteadyShot. We used a focal length of 35mm from quite close range and a shutter speed of 1/8 of a second. We’ve cropped 621×268 pixel sections from the original 3872×2592 images and resized them to 282×121 for reproduction here. Clearly the example with Super SteadyShot enabled has eliminated the effect of camera shake.

We found Super SteadyShot proved effective at eliminating or at least greatly reducing camera shake in a variety of circumstances, and, like the Konica Minolta 5D before it, a key selling point for the A100. It’s wonderful to have the facility regardless of the lens you attach, and is likely to influence other manufacturers to bundle stabilised lenses or face falling behind.

Sony Alpha A100 Anti dust

Sony has correctly identified dust as a major nemesis of digital SLR owners and equipped the Alpha A100 with two technologies to combat it. First, an indium tin oxide coating has been applied to the Low Pass Filter (LPF) to create an anti-static coating. This does not readily attract dust.

Secondly, the sensor is vibrated during power on and off, further dislodging particles; this didn’t impact startup times though. Like other digital SLRs, there’s also a clean CCD option in the menu which flips open the mirror and shutter, allowing you to manually blow dust away.

While we of course always welcome any attempts to reduce dust, foreign particles still made it into our DSLR-A100 and onto images during the test period. Illustrating this is a crop shown left which clearly shows the tell-tale faint disc caused by dust on the low pass filter; it can be seen in the lower middle area. To be fair, most of our images appeared dust-free, but a handful definitely had one or more visible marks. As such, Sony’s anti-dust system appears less effective than the one from Olympus.