|Color rendition & White balance measurements
Color rendition of the Sony Alpha 900 deviates slightly compared to the Gretag Macbeth Color Checker, however, it shows a fairly equal value over the sensitivity up to and including 3200 ISO. The colors come across as quite natural. The Sony Alpha 700 also tested in the DIWA Lab, delivered a slightly more accurate color. Measurement for color reproduction is carried out with optimized white balance and light metering, ensuring a result which the Sony A900 is able to produce under the best possible circumstances. The results for the white balance measurements show the ability of the Sony A900 to carry out a manually set white balance extremely precise. The camera shows a quite even value over the entire ISO range. The auto white balance encounters some difficulties with an overdose of incandescent light, and I find it is somewhat 'warm'. By applying a manual setting, the most neutral effect will be reached. By the way; you can adjust the white balance of the A900 to your own preferences.
ISO sensitivity of the Sony A900
The possibility of setting ISO values as you desire is a surplus value of any camera. Traditional films have a fixed ISO sensitivity, whereas it is possible to influence the camera's sensor in order to create a bigger playground. A camera manufacturer is eager to use these values and show them in the specifications. However, in practice, these values may very well differ from the genuine sensitivity and a deviation of 20% to 25% is not uncommon. The sensor of the Sony DSLR-A900 is also tested in the DIWA lab as for its sensitivity, and the ISO values did not meet the 200-1600 values. Deviations as much as 29% to 36% less sensitive show that Sony is clearly trying hard to control the noise. Even more astounding are the values measured at 3200 and 6400 ISO, where differences of respectively 43% and 57% are found. In other words, ISO 3200 equals ISO 2238.
|Noise reduction has been controlled well
The noise values on the Sony Alpha 900 do not disappoint us. On the contrary, we were nicely surprised by the Sony Alpha 900 with values that are close to the Canon EOS 1Ds Mark III, for example. This is an achievement Sony can be proud of. If you shoot in RAW and effectively reduce noise, you will obtain a perfect result. Up to and including ISO 800 this should not be a problem at all. At ISO 1600 and higher, noise becomes more visible and a precise exposure is required or more corrections have to be carried out in RAW afterwards. Not bad, in fact an excellent result by the Sony Alpha 900 that stands strongly in this high resolution class. For those who like to keep control over noise in their own hands; it will be a relief to know that the Sony A900 offers the possibility to deactivate the internal noise reduction all together, in RAW that is.
Dynamic range of the SLR camera
The dynamic range of the Alpha 900 is excellent. The entire range shows fine values and all the difficult dark and light areas in the picture come out greatly. All in all, a 24 megapixel picture looks excellent providing it was exposed well. Rich details in the picture and a good eye for the difficult light areas. Moreover, with a file this huge, enough possibilities are at hand to make a fine crop.
Sony A900 works well with ZEISS lenses
If you want to make optimum use of the Sony Alpha 900 you have to use the large amount of ZEIS lenses that Sony has built up over the past few years. Naturally, there are also a number of (cheaper) lenses on the list that are supported, however, the majority of these lenses are not able to live up to the high requirements of the resolution and the full format. The Sony A900 was tested in the DIWA Lab in combination with a Carl Zeiss Vario-Sonnar T* DT 24-70mm f/2.8 ZA lens. A lens that performs excellently with only a fraction of blur on the edges at 70mm. The remaining focal points are sharp from the centre to the edges.
Carl Zeiss Vario-Sonnar T* DT 24-70mm lens
Vignetting is only visible (+0.8%) at 24mm over the entire aperture range, although this can be neglected and does not diminish the quality at all. The Carl Zeiss Vario-Sonnar T* DT 24-70mm f/2.8 ZA lens unfortunately suffers from vast chromatic aberration. In particular the 24mm wide angle. Besides that, telephoto range of 70mm also suffers from purple fringing around the contours of a subject. And the lens, although not unexpectedly, suffers from vignetting at maximum aperture f/2.8 and in particular at 24 mm and 70 mm. The lens combines beautifully with a camera like the Alpha 900 and the occurrence of chromatic aberration is very sad.