Re: DSLR advice? What camera's and lens to consider?
Chris,
Noise level is pretty comparable across all those cameras when you compare the RAW files. The D50 JPEGs showed lower noise than D70 partly because of in-camera noise reduction that D70 did not have -- and the D70 JPEG engine wasn't too good in general either. The D80 and D200 may appear to have slightly higher noise (in RAW), but if you resize the results to 6MP for comparison w/ the D50, noise become very comparable and maybe slightly better. IOW, in actual practice for real world use, noise level is actually not worse. And if you want to increase in-camera NR (though this will cost you some detail loss), the D80 and D200 offer in-camera options for that.
Still, yeah, if what you want is better noise performance native to the sensor/RAW files, you won't find that in the D80 or D200. Significant performance increase in this area will likely require moving up to a camera w/ bigger sensor. That's partly why a lot of people want to see Nikon come out w/ full frame bodies.
Anyway, if high ISO noise performance is important to you, you'll probably want to check out the Auto ISO feature on the D50. Unlike the higher end models, the D50 only offers full stop steps for ISO settings unless you use its Auto ISO feature. With Auto ISO on, the D50 can choose in-between ISO steps like 1000 and 1250 rather than going to the next full step like 1600. What I'd often do in indoor/low light situations is start out in M mode w/ aperture and shutter speed dialed in and Auto ISO on so that the meter would determine ISO for me. However, since the D50 does not allow manual setting of those in-between ISOs, you'd have to stick w/ Auto ISO if you want to be able to use them to minimize noise.
Also, if you like shooting for in-camera JPEGs instead of RAW, the D50 (like all Nikon DSLRs) has a custom tone compensation feature that lets you use your own tone curve instead of the manufacturer choices. Some people like to load curves that produce a provia or velvia look for instance. Even if you shoot RAW, if you want to be able to apply the custom tone curve as part of RAW processing, you'd still need to shoot w/ the curve loaded in camera (though there is some inexpensive 3rd party software like Curve Surgery that can insert the curve into the RAW file post-shoot). Unfortunately, you can only load the curve into camera using Nikon Capture (and presumably the newer NX), not Nikon View. I used to use this feature on the D70 because the D70's default tone curve resulted in rather dark midtones (maybe 1/3-1/2 stop lower than most like), but this doesn't seem to be an issue on most other Nikon bodies. It's a feature that you may want to play w/ a little bit if/when you get Nikon Capture (or NX) or the 3rd party software I mentioned.
And if increased storage is not a problem to you, you may want to try shooting RAW+JPEG so you can have the RAW files for when you need that extra bit of IQ and the basic quality JPEGs for quick prints or quick resize for web presentation.
Finally, if IQ is of utmost importance to you, you may eventually want to check out some lesser known RAW converters created by Nikon shooters who aren't completely satisfied w/ what's already available. RAWMagick is one of these that seems to produce results that are noticeably better than Nikon's own software, particularly when some extra "massaging" of the data is needed -- RAWMagick is created by the same folks who created Curve Surgery. FYI, I actually bought RAWMagick Lite when it was still in beta (as part of their promo deal w/ Curve Therapy and Curve Surgery), but never got around to using it.
_Man_
