nikon d3100 for skateboarding?

You need a fast lens for best results. Something with an aperture of 2.8 or less is a good place to start. The larger the apearture the faster the shutter speed which gets you the stop motion stuff that you want. The camera should not be the problem but if you use a slow lens that will be.

The problem with the suggestions of the fast lenses like the f/1.4, f/2.8, etc lenses is that the depth of field will be so shallow that the skateboarder will probably be out of the focus plane by the time you press the shutter button.

It's more about shooting the right settings than just a fast (large aperture) lens.

You can reduce motion blur by using a short shutter speed. You will need more light to compensate, by widening your aperture, increasing ISO sensitivity, and/or using flash. Motion blur can also be shifted to the background by tracking your subject as you're taking the shot.

If you are shooting outdoors with plenty of daylight, all you need to do is set the short shutter speed. You will have enough light to compensate.

If you are shooting indoors, you may want to use your built-in flash.

You don't necessarily need to purchase anything, but you could get a wide aperture lens (f-number of 2.8 or smaller) or a speedlight.

Skateboarding is just another type of movement, your camera doesn't know that :) Any DSLR will be capable of freezing the shot and getting high quality shots. D3100 is an amazing model for that price!

Here's a DSLR Buying Guide - http://www.the-dslr-photographer.com/how-to-buy-ds...

Good luck!

The #1 sports lens is a 70-200mm f/2/8, in whatever brand you prefer (Nikon, Sigma, Tamron).