By close up shots, I assume you mean shots with more reach that get you closer to the action from the sidelines in the example of football or soccer photography.
I don't use Sony equipment, but I can assure you that the 18-70 lens doesn't have enough reach for most sports or for wildlife. If you go to Sony's website, you'll notice that Sony has several choices for lenses that will work for you at varying price points and effectiveness levels. At the higher price end you'll see a 70-200 f2.8 and a 300mm f2.8 lenses that provide decent reach and the ability to get good photos in low light situations. I use both of these lenses for my sports photography (I use Nikon equipment, however). Check out my sports photo blog that will give you an example of how these lenses can really get you the capability you'll need at least for sports like soccer.
Sony also has a number of other lenses that have great reach (300mm and higher), but also higher f-stop numbers. These lenses will be cheaper than the lenses mentioned above, but also won't be as capable of getting good photographs when the light isn't good. Just remember, the lower the f-stop number (f2.8 is about as low as it gets with lenses with reach over 200mm), the better the light gathering capability of the lens (and the higher the price and size of the lens). Higher f-stop lenses can have great reach, but can become useless when lighting conditions aren't optimal (like a cloudy day).
