Sat 03-Nov-12 05:12 PM | edited Sat 03-Nov-12 05:18 PM by dwight200
I went from DX to FF in '08 and had to update my primary lenses also so it was a real pain in the wallet. I recovered from that and have no regrets. I passed on the D3S because it looked like a small incremental change from the D3.
I just got a D4 and have used it for about 100 shots so far. It does a great job for indoor shots. Autofocus is fast and the ISO performance is very nice. I could use up to ISO 800 on my D3 before I saw significant noise. The D4 goes to 1600. Above that the noise is easily manageable up to 3200. Things are reasonable up to 12K and you can get useful images above that with processing. I've only tried a couple shots at 200K and they were pretty noisy but with downsampling and noise reduction you could do pretty well. I took one shot when it was too dark to see anything through the viewfinder and got a recognizable image.
From what I read the D4 ISO performance is similar to the D3S. However the autofocus is faster and there are new features that are worthwhile including more programmable buttons. I can't compare them directly not having had a D3S but I would say the D4 is advanced over the D3S.
I am not particularly interested in video although I have made a couple of short clips for documentation on the farm. Video was not the reason I got the D4 and I don't expect to use it extensively, but I'll probably use it a little. The rest of the time I can ignore it.
I'd say the D4 would be the best camera to get if you're focused on events, indoor work, or night shots. The D800 might be better if you are more into landscape photos or maybe real estate documentation. Remember that resolution goes as the square root of the number of pixels, so from 16 to 36 is about a 50% improvement. That doesn't interest me because I'm rarely resolution limited. I'm frequently sensitivity limited, so that's why I like the D4.
Newspaper work doesn't require resolution since they print with a fairly coarse halftone screen. Weddings rarely require prints above 11x14 (although I could well be behind the times there). Anything on the internet will be limited by the screen you're viewing it on. Personally I think 12 MPx is probably enough so the D4 (16 MPx) or the D3S (12 MPx) would fill the bill. A used D3S would be a somewhat less expensive way to get started in FF. While it's nice to use the same format for both your primary and backup cameras it's not absolutely necessary. Fully interchangeable lenses is a big plus there so you might want to use FF lenses on your DX backup.