What are other good lenses for the nikon d3100 that give the background Blur (Bokeh)?
I know they are putting a new lens out on the market soon, but is there another good one? If the price is below 500 that would be wonderful.haha
Any lens that is compatible with nikon and is able to give an aperture of 1.8 or 1.4 or 1.2 is good for a background blur and bokeh. Most likely those type of lenses won't zoom but are great for portrait photography. Try looking at this one. Good luck!
Nikon AF-S DX Nikkor 35mm f/1.8 Lens for Nikon F-Mount Digital SLR Cameras
http://reviews.bestbuy.com/answers/3545/product/9542328/nikon-af-s-dx-nikkor-35mm-f-1-8-lens-for-nikon-f-mount-digital-slr-cameras-questions-answers/questions.htm?page=3&sort=answers&dir=asc
You can blur the background with any lens… Haha…
Generally, one which has a fast maximum aperture. Like this one: http://www.amazon.com/...004Y1AYAC/ which also falls well under your price requirement. Keep in mind that background blur and "bokeh" are two different concepts. Bokeh is defined as the quality of blur, and is usually lens specific- affected by the shape of the aperture. A more rounded aperture will produce smoother blur (good bokeh). The 50mm f/1.8G has a rounded aperture, as opposed to the lens it replaced (the D version).So it should have pretty good bokeh. I would also recommend the 35mm f/1.8G. You could buy both for under $500, which is really nice.
Background blur is not "bokeh". You are referring to narrow depth of field. (bokeh has to do with quality, not the amount of blurriness).
If you want a narrow depth of field, get a lens with a large maximum aperture (small f-stop number). Like f2.8 or smaller.
I suggest reading your camera manual as well as a good book on general photography.
I have a D3100 and I just purchased the Nikkor 35mm f/1.8 a few days ago and it is AWESOME! I could get really nice bokeh with it and the sharpness and colors of the pictures is amazing. The AF-S motor is extremely quiet and fast. And it only costs $285!
Another nice thing is that it's got a metal mount so you don't have to worry about it breaking when you attach it to the body. In my opinion, this is a must have prime lens for any Nikon DX-Format DSLR user!
The one they just released is the 50mm f/1.8G AF-S DX but it's more expensive and the only difference is the focal length. I find 35mm more useful than 50mm anyway.