Sony Alpha A900 24.6MP Digital SLR Camera (Black) Review

Sony has finally claimed the high ground with its long awaited full frame sensor.And at 24 megapixels, this sensor probably achieves the nominal resolution of 35 mm color film.According to Digital Photography Review, this sensor achieves a resolution of 2,700 lines per 24mm of sensor height, which equals 2,700*25.4/24.0=2,858 lines per inch.

This camera is well built with plenty of buttons to control its functions.It is easy to use and produces stunning picture quality when used with high end Zeiss, Sony or Minolta lenses.When used in continuous shooting mode, the camera captures 5 RAW images per second for 3 seconds, for a total of 15 images, before its image buffer fills and the image capture rate becomes limited by the speed of the Compact Flash card.

However, the A900's high resolution sensor is somewhat susceptible to noise.Packing 24 megapixels into this full frame sensor means that each pixel collects less light per unit time than does each pixel of a 12 megapixel full frame sensor.In consequence, the 24 megapixel full frame sensor is less immune to noise than the 12 megapixel full frame sensor.When no in-camera noise reduction is applied by the A900, noise becomes apparent at ISO 800 and it becomes objectionable at ISO 1600.However, it is possible to apply out-of-camera noise reduction software such as Noise Ninja to reduce this noise.Another possibility is to resample a 24 megapixel image to obtain a lower resolution image with less noise.

The A900 places large demands on the computer where images are stored and post processed.The best image quality is obtained from RAW mode which consumes 36 megabytes per image file and stores 12 bits per pixel.Compressed RAW (cRAW) mode, which consumes 24 megabytes per image file and appears to store only 8 bits per pixel may be less useful for subsequent photo editing. And opening one of these 36 megabyte RAW image files using Adobe Photoshop can be time consuming. I have upgraded my 1.5GHz PowerPC G4 Mac mini to a 2.0GHz Intel Core 2 Duo Mac mini in order to decrease the time required to open a RAW image file to a reasonable delay.

The high resolution of the 24 megapixel sensor is achievable only with high end lenses such as the Zeiss 85mm f1.4, 135mm f1.8 and 24-70mm f2.8 lenses, (presumably) the newly announced 16-35mm f2.8 lens, as well as the Sony G and Minolta G lenses.My own measurements with the Imatest lens test software reveal that many of the lower quality, non-G Minolta lenses (and presumably also the equivalent Sony lenses) are not sharp enough to exploit the high resolution sensor.Exceptions to this statement include the Minolta 28mm f2, 50mm f1.4 and 70-210mm f4 lenses, which are not G lenses but are close to G in quality.Nevertheless, be prepared to purchase an expensive set of lenses if you want to get the most out of the A900.

For these reasons, the A900 is a camera best suited to those who demand, and are willing to pay for the highest possible resolution from a digital SLR.For those who would prefer to invest less money in the camera, lenses and computer, the Sony A700 is another professional camera with a 12 megapixel half frame sensor.And, according to one comment to this review, Sony's recent firmware upgrade to the A700 now provides in-camera noise reduction that appears to be equivalent to that of the Nikon D300, a fact that makes the A700 a bargain at its current price of $999.




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Digital Camera Labels: Sony Alpha A900 24.6MP Digital SLR Camera (Black),Sony,DSLR-A900