To measure and compare the Sony DSLR-A100's noise levels we photographed
the standard Gretag Macbeth ColorChecker with it and a number of rival
models at each of their ISO settings.
The crops are taken from the original images and presented here at 100%.
To compare typical noise in skies and dark shadows the crops were taken
from patches 3 and 24 respectively.
Up to 400 ISO, the Sony DSLR-A100's noise levels are pretty much in line
with the Canon EOS-350D, Nikon D200 and Sony R1, but at 800 ISO and above,
the Sony delivers a noisier result than its rivals.
We're not surprised the Canon 350D beats it at higher sensitivities based
on both its lower resolution sensor and Canon's reputation for low noise,
but the Nikon D200 also out-performs it at 800 ISO and above, despite both
models having essentially the same sensor. Clearly Nikon's image processing
/ noise reduction engine is superior in this respect. We would also like
to have seen a 3200 ISO option on the Sony DSLR-A100, even if it had been
very noisy.
Note: we have compared 100% crops from each camera measuring 136x136 pixels. Since the Canon 350D has a lower resolution sensor, its crop therefore represents a slightly larger area relative to the others. That is, any artefacts visible on the 350D crops would be slightly larger and more obvious than the other three if each image was reproduced at the same physical size. In reality though, the actual difference in area is very small. The Sony A100 and Canon 350D crops represent 3.5% and 3.9% of their total image widths respectively. So while the Sony A100 artefacts would appear slightly smaller than the Canon 350D on prints of identical size, the A100's noise levels would still be visibly worse at higher sensitivities.
