Quote Originally Posted by Elisha View Post
The D90 has an improved sensor and is better at low light than the D300.
And I'm pretty sure the new D300s may get the newer improved 12MP sensor of the D90 or maybe a better one as well.
D90, D300 and D300s actually all have the same sensor. I believe the D300 and D300s may have more advanced EXPEED processors which is where the difference would come in. Especially between the D300 and A700. Though the D300 and A700 do not share the same sensor they are both created by Sony and they are very similar.