Nikon D3 advantages
100% viewfinder coverage
This is the D3’s main advantage over the D700, which only has a 95% coverage.
Nikon D700 advantages
Having the grid lines appear in the viewfinder aids composition and keeping the horizons as straight as possible.
The grid lines can be turned on or off by setting the related custom function according to your preference.
The popup flash on the D700 allows you to wirelessly trigger other Nikon Speedlight flash units that are compatible with Nikon’s CLS (Creative Lighting System).
Dust-cleaning image sensor
The D700 has the added convenience of being able to vibrate its imaging sensor to shake off dust.
Smaller dimensions, lighter body
- D700: Approximately 147 x 123 x 77 mm (5.8 x 4.8 x 3.0 in.)
- D3: Approximately 160 x 157 x 88 mm (6.3 x 6.2 x 3.4 in.)
Weight (without batteries)
- D700: Approximately 995 g (2.19 lb.)
- D3: Approximately 1240 g (2.7 lb.)
Photographers who shoot mainly events at wide to normal telephoto focal lengths (say 16mm to 150mm) would tend to appreciate the smaller and lighter D700 body.
Read Thom Hogan’s excellent summary on the pros and cons of the D3, D300 and D700.