Difference between 50mm DX and FX?

So I have a Nikon D3100 camera (DX) and I'm thinking of getting a 50mm prime as my first lens (other than the kit lens) however Nikon doesn't sell a 50mm DX lens as far as i can tell. I know some people say it does make a difference and others say it doesn't, so I'm confused. If I use a 50mm FX lens on my DX camera will it be exactly as it would be if i had a 50 mm DX lens on my DX camera. Will it crop it at all? Please explain it too.thanks!

Added (1). I'm thinking of getting the Nikon 35 mm DX lens, but if i can get a 50mm i think that would be a better use of my money, i can only get one or the other not both.

Added (2). So, Andrew, I'm still a little confused. If i get a 35mm DX for my DX camera it'll show up as a 35 mm should. But if i get a 50mm fx for my DX camera will it seem like i cropped it? My goal is to have the equivalent of a 50mm on my DX, not only in view angle and focal length but also the zoom or closeness of what I'm photographing.

Your camera takes both DX(cropped-sensor) and FX (35mm negative-sized sensor) lenses, Nikon only make an FX 50mm lens because it's all they (or you) need.

50mm is a standard lens on FX, but on your DX it's a short telephoto lens, its fast aperture and angle-of-view making it ideal for portraits, but a touch too long for general photography.

DX lenses used on FX bodies do, indeed, crop the image to FX size on Nikon (unlike Canon, whose EF-S (DX equivalent) lenses don't fit EF (FX equivalent) bodies. EF-S bodies take both lens types). Sony don't make the distinction, and Pentax don't (as yet) offer a full-frame body.

Which lens you buy depends on what you want to do, 35mm to see what your eyes do, or 50mm to give you that little bit of reach. Try your standard zoom at both settings to see which would be the more useful (the difference is in the lens' speed, not its angle-of-view - both of which are already covered).

Of course, you could always get a 55-200mm AF-S as your second lens, and remember that any lens you buy must be motorised.

The 50mm lens will work fine on your camera. In fact, it will probably work better on your Dx camera than on a Fx camera.

The reason for this is that you are not using the entire lens, but only the center portion of it. The center of most lenses tend to be the most sharp area, so you will not have the fall off in quality a Fx user would have.

In reality, the only difference between Dx and Fx lenses is that the Dx lenses are a smaller diameter as they don't need the entire amount of glass. So think of Dx lenses as a trimmed down Fx lens.

Also, when used on a Dx lens, the lens itself will seem to be a bit longer. The 50mm lens is still 50mm on either Dx or Fx, but it is a bit like the Dx camera having a bit of digital zoom. For your camera, with it's 1.5x crop factor, the lens will appear the same as a 75mm lens would on a Fx camera.

Finally, make sure you buy the AF-S version; yea, the more expensive one. The AF "D" version does not have an internal focus motor - but relies on the camera for that. Since your D3100 does not have an internal focus motor, you will not be able to autofocus with the AF "D" lens; only with the AF-S lens.

If you want the equivalent of a 50mm lens then you should get the 35mm DX. A 50mm lens will not offer the same field of view (FoV) as a 50mm lens on FX. Due to the crop factor it will give the same FoV as a 75mm lens would on an FX camera.

Nikon DX sensors are 1.5 times smaller than the FX sensor.So, when you mount a lens on the body you half it and add that back to the focal length of the lens. So a 50mm 1.4D on a DX body (half of 50mm is 25mm, 25mm+50mm=75mm) would be like a 75mm lens on FX. If you get the 35mm DX then you are looking at the focal length equavalent of a 52.5mm lens which would be much closer to the 50mm you want in the first place.

The 35mm f1.8G DX minimum focus distance is 11.8 inches (30cm).
The 50mm f1.8G minimum focus distance is nearly a foot and a half (45cm).

As you can see from this, the 35mm f1.8G DX is the way to go for you.

Nikon 35mm f1.8G DX at bhphotovideo.com: http://www.bhphotovideo.com/..._1_8G.html

Nikon 50mm f1.8G at bhphotovideo.com: http://www.bhphotovideo.com/...html.co.jp

If you want the technical information then click the specifications below the lens photo.

Happy shooting