The new Sony Alpha 500 JPGs seem to be quite much better than JPGs from the Alpha 700 and Alpha 900. Both detail resolution and high-ISO noise are significantly better. I just quickly compared four Minolta/Sony DSLR at ISO settings from 200 to 12'800: The brand new A500, the one-year-old A900, the two year old A700 and the now five years old Minolta Dynax 7D. The results are interesting and mostly self-explanatory.

A few technical remarks:

All photos were taken using the Minolta AF 1.4/85mm lens at f5.6. At these settings the lens produces images with extraordinary amount of details.

All photos were taken using the AF of the camera, the sensor pointing to the bright chimney seen in the 100% crops below. Obviously the Dynax 7D AF is working correctly, while my A700 seems to have issues. The A900 AF was adjusted using the Micro AF function, and the A500 autofocuss worked perfectly with many of those lenses that need AF adjustment on the A900 (e. g. Minolta AF 2/100mm).

Above: Full image taken with A900. Due to the smaller sensor size, the A700 and A500 pictures are smaller, but 100% crops look almost identical since the pixel size of all three DSLRs is very similar. The Minolta Dynax 7D however has bigger pixels; therefore its 100% crops look different.

Up to ISO 400 the differences between A900 and A500 are small:

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At ISO 800, the A500 JPGs have much more details and considerably less noise than A900 JPGs. The improvement is clearly visible:

While A700 / A900 JPGs look quite unpleasant at ISO 1600, the A500 JPGs are perfectly usable. There is some detail loss, but the color noise is very well controlled:

At ISO 3200 the differences between A700 / A900 and A500 become even more pronounced. The A500 color saturation is now slightly reduced (comparted to ISO 1600), but still better than the A700 and A900. Noise and detail resolution both are much better compared to the A700/A900:

At ISO 6400 the low-contrast details are lost - but the general impression of the A500 image nevertheless is much more pleasant. And be aware that A500 images can have lots of detail if the microcontrast is somewhat higher than in this example!

ISO 12'800 is a compromise. But still better than A900 images at ISO 6400:

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