I want to buy a wide or fisheye lens for taking panoramic (360°) photos. My camera is the Nikon D7000 . I am a little bit confused about FX and DX lenses; could you guide me to select the correct lens?
I agree that a wide angle lens gives too much distortion to allow auto-stitching software to function correctly.
The 50mm Nikkor 1.8 might be a good choice, but bear in mind that 50mm on a Nikon cropped sensor is 75mm. This might make it a bit too zoomed in for your liking. It really depends on your subject matter. If it fits, the 50mm is a great lens. It's extremely sharp for the money. And can be used for great portrait shots too.
If the 50mm's no good, Nikon do a 35mm 1.8 that might fit better.
The lens you choose should first depend on the resolution you need from you panorama. You can do it with pretty much any lens but if you go with a 50mm, as someone suggests, you will be stitching a ton of images. The more images, the more chances of screwing and the most chances of things (people and vehicles) moving between frames and accross boundaries.
If resolution is not important you can do that in very few shots with a circular fisheye. Many panorama software are highly specialized nowadays and support this time of lens. A Sigma 4.5mm fisheye would give you the least amount of shots. You can get more resolution using the Nikkor 10.5mm fisheye but still not need that many shots.
If you do not have panorama software already, I have reviewed several - both free and paid ones - at Neopanoramic. Not all perform the same and not all support fisheye lenses. If you ever see panoramas of interiors with plenty of people or in crowds, they are almost always done with a fisheye lens.
FX lenses can be used with a full frame or cropped sensor body
DX lenses can only be used with a cropped sensor - if used on a full frame camera, you will have dark areas in the corners.
If you have a D7000 you can use either type of lens (D7000 is a cropped sensor camera, not full frame )
You can get wide/panoramic images with your camera in two ways basically:
if you take multiple photos, it's easier to do if the lens doesn't have a lot of distortion at the edges, so a wide angle lens tends to be a disadvantage
Nikon makes a 10.5mm DX lens. Not sure if it's quite what you had in mind when you said panorama. It would get you around 180 degrees, not 360.