Sony Alpha 100 June 2006 launch report

Focus and sharpness

As Dynax 7D/5D owners, our critical questions are all about the AF speed and accuracy, metering consistency and above all the sharpness and image process quality of the Alpha 100. I had already tested the Nikon D200, known to have a similar 10.2 megapixel sensor, a few months earlier. My feelings were that I would not rush out to spend twice as much on that as our 5D, which offered a little less resolved detail from comparable optics but a bit more ‘snap’ to the colour and contrast.

But I was considering comparable optics not identical – and both moderately priced mid range zooms. Mounting top grade Minolta glass on my 7D and the A100, it was very clear that the A100 could extract finer detail effortlessly. Returning to base with the images, I had shot raw files (.ARW format) throughout, and Sony had the foresight to provide Adobe with advance information which meant I was able to process these using Adobe Camera Raw straight away.

Detail capturing capacity of the Alpha 100: this shot taken during the launch in Morocco, using a Minolta 100mm f/2.8 Soft Focus lens set to sharp focus and stopped down to f/8, has been processed from the raw .ARW file using Adobe Photoshop, and its colour and contrast enhanced to resemble a slide film like Velvia. You can view the original image, together with an unadjusted export and an in-camera JPEG and dozens of other Alpha 100 examples, by visiting  http://www.pbase.com/davidkilpatrick/alpha_100

The most careful shots, with the highest quality lenses, showed that the A100 has very accurately set-up focusing. Tiny errors are easily seen in a digital image of this size, and I could spot where the camera was clearly preferring foreground objects to background. The most common AF error – shooting two people with a space between them and ending up with the distant view sharp and the people blurred – seemed to be programmed out of the A100’s system. It picked the people, or person, every time.

The new exposure system has a staggering 40 metering zones instead of the familiar 14. Since this was a camera trial, I left the exposure to the camera to handle with a few adjustments to test what under or overexposed shots looked like. Again, exposure accuracy goes a step beyond the 7D and 5D – as you would expect, that’s progress.

A typical in-camera JPEG from the Morocco shoot – taken using the 11-18mm Konica Minolta zoom, which proved its true sharpness for the first time on the Alpha 100. The metering and dynamic range were excellent with good detail in shadows and highlights, and no post-processing required for this result.

There is more still. The Alpha 100’s new sensor and BIONZ processor (think ‘beyond’ – the French pronounced it best) combine to give a dynamic range compression well beyond any DSLR I’ve used. Even the Fuji FinePix Pro S3 with its additional set of sensors to capture highlight detail and the Kodak DCS Pro SLR with its ERI-JPEG format never did any better than this. It was possible to get highlight information in raw files to go beyond the safe range of unclipped full colour adjustment, but only in extreme circumstances. Judging subjectively, the Alpha 100 will show natural-looking detail in highlights at least one step brighter than the 7D or 5D while retaining full shadow information.

All such features have a trade-off, and in the Alpha 100, colour is a little more neutral than either the 7D or 5D. Technically it is more accurate, but if you are used to the saturation and warmth of the Konica Minolta’look’ you will find the Alpha 100 a little understated. When processing from raw, adjustments can make either type of colour look much as you want. JPEG shooters will probably be turning the colour to sRGB+ (vivid).

White balance is an issue I need to investigate, as the JPEGs all look great but Adobe Camera Raw reported some very low apparent Kelvin values for daylight shots. It is well known that ACR does not use the maker’s original White Balance information, and I think this is an error in ACR not the file format. We shall be looking at Sony’s own processing software, and other proprietary converters as they gain the ability to process .ARW files.

The bottom line is that the Alpha 100 produces pictures with accurate but fairly neutral colour, very high sharpness, considerable compression of subject contrast, and very low chromatic noise. At ISO 100 to 400, luminance noise increases gradually from invisible to just detectable; at ISO 800, there is some discernable chromatic noise added to the luminance pattern; at 1600 noise remains tight but definitely present, with more muted colours. You can see our noise tests from this shoot as shown below at full size here.

Compared to the 7D or 5D, I would say there is a more regular luminance noise (like well processed film grain) increasing in proportion to ISO; and a less prominent coloured noise, which only becomes strong at 1600. Random noise artefacts appear better controlled, but I’ll need to try night and low light shooting to see whether there is a hidden gain. In theory the 10 megapixel sensor can not be as noise-free as a 6 megapixel sensor. In practice I reckon both the in-camera processing, and typical raw conversion with image post-processing, will yield at least as good a 1600 ISO result from the Alpha. It does not offer 3200, but 3200 is a setting I disabled on my 7D after using it once accidentally for important shots. In emergencies just shoot at 1600 and underexpose by a stop – the end result is much the same!