Both Sony A700 and Nikon D5000 have APS-C sized 12.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the A700 and D5000 sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A700 and Nikon D5000 Cameras
Sony A700 and Nikon D5000 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Sony A700 and Nikon D5000 sensors have been tested by DxO and the results show that D5000 has a better overall score of 72, 6 points higher compared to A700's score of 66.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A700
66
22.3 bits
11.9 Evs
581 ISO
Nikon D5000
72
22.7 bits
12.5 Evs
868 ISO
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Sony A700
or the
Nikon D5000 ,
including hyperfocal distance.
