What camera lens should I buy?

Oh very good camera to use, I have one and I absolutely love mine. Truthfully any nikon lens won't sacrifice quality from what I've seen. The only thing I would recommend making sure of is that lens is automatic focus so you don't have to fully rely on your own focusing skills. Since the ones that are automatic have an option to turn it off, you get the best of both worlds. That being said I use a 75-200mm and it has a great distance to it, the next lens up I believe goes to 300 which is good as well. It really depends on how far you want it to go, but typically I can sit on one end of the football field in the stands and still be able to get pretty good zoom on the other end with great pictures. Hope this helps, let me know what one you decide to get! I've been thinking of upgrading my lens lately, when I have the money to that is.

The D3000 does not have a built-in autofocus motor, so unless you like to focus manually, you will have to buy an AF-S lens, preferably a DX format. This page has more information: http://www.nikonusa.com/Nikon-Products/Camera-Lenses/Sports-and-Action/index.page I would look for a lens which either overlaps the range of the one you have (for example, a 28-300) or is adjacent to it (55-300). Unfortunately, because of the electronics built in and also because of the engineering used to make them as light as possible, lenses don't come cheap. Also, because of their complexity, you need to be specially careful if you are going to buy second-hand. In the days of SLR film cameras, it used to be possible to get very good third-party lenses from companies like Tamron. These days the price difference is not as much, the range is limited and you need to be much more careful about compatibility.

I used to use a Nikon 18-200 VR lens but went to a Sigma 18-250 OS lens. Both lenses give great results but the Sigma is quieter and faster in auto-focusing, as well as providing a longer focal length. Bear in mind that any lens at maximum focal length is going to give you a less sharp result but even this can be overcome, somewhat, with post-processing. The aperture you use is also an important consideration, no matter which telephoto lens you use. An aperture of f/11 is considered to be the sweet spot for the sharpest photos. It depends on what you are taking, though, and how creative you wish to be. I'm sure you know that the wider the aperture, the shallower the depth of field, and the smaller the aperture, the greater the depth of field. Taking photos with a wide aperture will increase the shutter speed but will likely be less sharp. So if you are using a long focal length at a wide aperture, you may not get the results you're looking for. Whichever lens you get, try the f/11 aperture and let the camera choose the shutter speed. Obviously, low light situations may demand either a wider aperture or the use of a tripod. And with most lenses with VR (Vibration Reduction) or OS (Optical Stabilizing) you need to turn those off when using a tripod. Some of the latest lenses have sensors to overcome the need to turn off VR or OS.