Now here's the first set of comparisons. And the most important too!
Would you believe that you could see the differences between both combos at images downsized from their original glory to 500 pixels width?
Well, me neither!
Here goes, but you have to guess, which is which.
Both images were shot from the same vantage point within seconds of each other.
Click through the images to get access to the large originals.
The first image is sharper, isn't it? Yessssss!
Now sharper is better, so the first image must come from the more expensive combo, the D700 + 28-300mm? Wrrrrrrrong!
Let's have a closer look now at a 100% crop (sorry it's a little oversized):
Both images were shot at f/5.6, 1/250 sec, ISO 200. The first/left image had to be lifted +0.3 EV to match the 2nd/right one.
Now, what do you see?
Yep, the second image is also sharp, but only in at the closer flowers, the background is more out-of-focus than in the 1st image. Obviously the first image has a greater dof and less blurred oof-rendering.
This comaprison is testament to the optical law, that the larger sensor produces less dof. To achieve the same effect on the D300 you need to shoot at a one stop larger aperture. So if you shoot wide open to isolate your subject you would need a 18-200mm f/2.5-4.0. A lens that you simply cannot buy!
So the FX body gives you a background isolation/blur with your existing lenses that only some expensive larger aperture lenses could get you. That alone could easily save you extra the money to get a D700 of a cheaper DX body.
On the other hand, if you need deep dof to get everything sharp from front to back, you need to stop down the FX-combo by one stop which either gives you a longer shutter speed with the added risk of shake or you need to crank of the ISO one notch to compensate for that.
But if you're interested in maximum dof, you need a point&shoot (or use your mobile phone). For a dof-comparison of a p&s to a D300 looky here
Thomas (beware: Nikon-fanboy and moderator!) My Lens Reviews
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