Usually it's not easy to say this on a gear forum (a place where chronological technical advances always mean better)...
I'm 100% base ISO shooter, and I believe I have a good eye to tell differences in IQ at base ISO between camera models.
At ISO 100, I still believe the D200's IQ is among the very best there is.
Please note, this has nothing to do with DXO charts.
I'm not talking about SN ration, nor DR numbers, etc.
I'm talking strictly about what my eyes see, and my overall gut feeling about the picture.
IMO, the D200 renders nicer than the D700 (which I have used for 5 years), and yes, nicer than the D800 (from all samples I could gather).
About that gut feeling I've mentioned, the D200's images are very close to those I get with my Leaf Aptus digital back.
This should come as no surprise, considering they're both CCD and both made in a time when the compromises were different than today's.
For example: both the D200 and the digital back come from an era when color reproduction and base ISO IQ were much more important than High ISO.
That's one of the reasons you have really strong CFA in these cameras, great colors, great base ISO and terrible high ISO.
These cameras were designed with different compromises in mind.
So as long as you're a low ISO shooter, you'll be completely satisfied with the D200.
The speech would be different if high ISO is your thing, though.
Cheers!
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Marcio Napoli
www.marcionapoli.com