Upload & Sell: On
Gregg, you asked about Zeiss 35 f:1.4 without specifying ZE (EF mount for Canon) or ZF.2 (F mount for Nikon). I have and shoot Canon FF (5DII), but the lens is the same. And the questions you ask apply to both systems.
Is it hard to focus manually at f:1.4? Basically at f:1.4 every 35mm lens has very thin DOF, especially for close ups. This is true both for AF and MF shots. So, yes, it takes some doing. But have I lost shots because I was not able to nail it? No, because I shoot, chimp, and reshoot if necessary, until I nail focus. Because, and I might have started with this, shooting this lens wide open is not for "live" shots (kids, dogs, action).
Part of the answer depends on how good your viewfinder is (D700, D3?), and whether you can use a special focusing screen for MF. Canon has them, so I assume Nikon does as well.
How good is the lens wide open? Compared to stopped down, it is not as good, but that is true of all lenses, including Canon and Nikon 35 f:1.4.
Hereafter is a 100% crop of a wide open shot handhels, no lighting. About as hard as it gets. And I am not a wizard, though I have only MF lenses on my Canon, so I have practice on my side.
Why did I choose this lens? The most spectacular feature is its bokeh. One reviewer said "bokeh alone is worth buying this lens". Then you notice huge amounts of detail, including minute detail, And colours, and contrast. And extraordinary spatial precision, which is sometimes called the "3D" effect for which Zeiss lenses are famous. I used to shoot a Canon 35L f:1.4, then traded it for a Zeiss 35 f:2.0 and felt it was a trade up. Then to the Zeiss 35 f:1.4, which is better yet, and, IMHO, the best of the Zeiss ZE/ZF lineup right now.
Suggestions: two things. Read up. I suggest Lloyd Chambers' blog, Diglloyd, which you can find here
There are mutlitple sections, one is free, others are not. He is very knowledgeable about Zeiss lenses, and publishes comparisons with other top-of-the range lenses too. I am pretty sure that he has a comparison with the 35G online.
Also, rent one, I am sure that Lensrentals offer that lens for rental. That way, you can familiarize yourself with it in real life before you take what is a fairly expensive plunge, should you not happen to like it.
Hope this helps.
Canon EOS 5D Mark II 35 mm f/1.4 1/13 sec 100 ISO 0.0 EV