Question: I'm going to a boat cruise tonight in London. With the following kit to choose from:

* Nikon D7000
* Nikkor 35mm f/1.8
* Nikkor 16-85mm f/3.5-5.6
* Nikon SB-400
* Yongnuo YN-465

I will definitely have both lenses with me, but I don't really like switching between the two too much. Do you think it'll be more useful to use the 35mm (with or without flash), or use the zoom lens and rely on flash all the time? The fact that the boat is moving all the time also means that, when I see something interesting, I need to be ready to take the shot straight away - the scene will have totally changed by the time I manage to change a lens.

Majority of the photos I will be taking will probably be of people, both indoors and out on the deck against the cityscape. But there will still be plenty of opportunities for pure cityscape photos as well, e.g. the house of parliaments, tower bridge, the few skyscrapers.

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This was originally part of [another question on photo-SE](https://photo.stackexchange.com/questions/15371/advices-for-taking-photos-on-a-boat-cruise-at-night).

Answer: 
Both of the previous photographers are only thinking two dimensional; shutter speed and aperture.
With a D7000, set the aperture for the depth of field required & the shutter speed required to freeze actions or let the VR compensate for motion and the camera will select the appropriate ISO for the availalbe light.
For true night shooting, carry a very small flash light & shoot manual focus. Walking around the docks shooting boats light up for Christmas use F8, with VR turned, Auto ISO on and the camera set for a high ISO noise reduction.
In general, I'd take the zoom. Having the wide angle (16mm) is a tremendously useful thing when taking landscape/scenery shots, especially on a crop factor camera like the D7000. Having 85mm on the long end can be very handy too, especially as you'll want to be picking out details from the boat.

However, if you really want to take night shots, the f/3.5 (at best) aperture of your 16-85mm is not enough. You're really going to need the f/1.8 of the 35mm.

On the other hand, 35mm isn't a great focal length for daytime landscapes; it has neither the wide angle for good vista shots nor the zoom for detail work. The 16-85mm is really the lens you want for most of your daytime work.

So, I see it as a tradeoff between night shots and space. If you really want the night shots, take both lenses. If you really value the space, forget the night shots and leave the 35mm at home.

Fortunately, the 35mm is small and light, so it won't be that much of a burden. And you won't need to change lenses that often; put the 16-85 on during the day, and switch to the 35 once it starts to get dark.