Whoa ... this is a biggie, and really isn't that simple to answer.
If you were someone with an E4xx twin lens kit and were wondering about dropping some serious cash on the D700 system, I'd say go for it, and you'd simply be utterly gobsmacked at the results and the difference in almost every conceivable way.
But you're not. You're someone with a pair of E3 cams, and also some VERY nice lenses. And while I think the D700 body is super, it really is going to be an odd thing to do, to sell the 35-100 and 12-60 (two excellent lenses) and just replace them with two, dare I say mid range, primes.
I'm thinking of a used D700, 85f1.8 and 35f2 all Nikon. To fund this, part with one E3, 35-100, 12-60 and the STF22. Basically keep the Oly for "long distance" and the 8 mm which I love doing Virtual tours with...keep or part the 50f2, leaning toward keeping though. Maybe eventually sell the 8 and pick up the Nikon 16 fisheye, no rush though.
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I can't imagine going all Nikon since the "long lenses" to match the 50-200 with or without the EC20 in FOV just cost an arm and leg...the 80-400 I hear is just too slow.
Well .... everything is relative. For the best part of a year I hardly touched my oly stuff and concentrated on learning the Nikon way of doing things, and even though quite a few of my lenses were pretty old, screw drive models (which are considered 'too slow' by a whole load of people), I thought they were ok. Then one day when I decided to go for a jolly and I dug out a 4/3 camera with my trusty and much loved 50-200 on it, it was "WTF is this POS!" as the Zuiko racked back and forth (slower than nearly all the nikkors) when it couldn't lock focus .....
After a while, muscle memory came back, and I remembered what it was like shooting with it and what to do, but before you make any judgments, I'd try some of these lenses out if possible. (note that I'm not saying the 80-400 is any good (I doubt its 50-200 quality IQ wise) - I've never owned one - just saying that you should be wary in passing judgment as many people will be comparing stuff to the top Nikon AFS lenses that are VERY fast)
Anyhow seems the D700 with the 2 lenses would be a nice low light set up and should have wonderful portrait results (ie does the 85f1.8 and 35f2 out of focus results on full frame match the 35-100?)
The 85mm f1.8 is a very sharp lens. The bokeh is fair. Its not as nice as say the f1.4 version or the long f2.8 zooms, however I have to be honest and say that while the 35-100 is much better than the 50-200 bokeh wise (and of course I'm talking proper use of bokeh - not just aperture), I've still seen disturbing artifacts (or at least not as pleasing renderings as I'd have liked) with the f2 lens as well, so I wouldn't be surprised if the Nikkor is about on par. However its going to be an f0.9 equivalent dof wise! so you are going to get a significant advantage that way.
The 35mm f2 ?? hmmmm... lots of people don't rate it THAT highly and its one of the reasons that so many pros got pi$$ed when they released the new 35mm f1.8 in DX and not fx. but again ... everything is relative .... its cheap, its cheerful, but I bet it takes ok pics. I've stayed away from that one, but then I've got two f2.8 zooms that cover that focal length. So I haven't felt the need. Now if they released a corking 35mm f1.4 prime, then that's a different matter .... (a few months more maybe? hate to think of the price though)
Down the road, maybe rent some big long glass if the need arises, I'm sure soccer photos with a 300f2.8 and full frame would be the cat's meow for isolation (as were the 150f2 Oly's...not a zoom again though and those darn soccer players keep moving forward / backward!)
Yup. There is a reason pros use the big primes though. The IQ is incredible. And the primes take the teleconverters very well.
However as you've pointed out the lack of zoom can be a PITA. Hence Nikon make the 200-400mm f4. Not cheap. But renting one of these might be an option, and of course its the same isolation as the 150mm f2, but it IS a zoom
The Oly alternative, sell the 12-60 and STF22 and toss in some cash for the 14-35...I keep seeing these 14-35 threads come up though with focus issues..
For anyone who needs to focus in low light. I would be very, VERY careful in buying a 14-35 that you can't take back for a full refund if it doesn't perform as you want. I also have seen far too many people who shoot as I do with issues and I've used one myself so I know what the problem is like.
The other thing that irks me is that the 24-70mm f2.8 nikkor is much cheaper and infinitely more usable for most people with the extended range. Plus its faster by a stop in real terms. If you had an E3 and a D700, personally I think its a no brainer in getting the Nikkor over the Zuiko in this focal range.
would the Nikon be fooled also by the net in low light...before the sun set no issues at all with the net and team photos!
No camera has infallible AF. There are just different levels of fallibility! The question is where the error threshold lies. My experience tells me that the Nikon threshold is further than the oly one, so there will be a point at which the Nikon will work, and the Oly won't. Increase the difficulty of the light, and eventually the Nikon will also stop working. I believe Canon is somewhere in the middle of these two levels (but then with them, it does depend on the model of body far more)
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