Recently I've been getting a lot of questions about clarity. This leads me to the answers about lenses. You know if you do not have a good lens you do not have a good photo- generally.
The reason I say that professional SLR is much better than a prosumer camera or a point and shoot is not because of my desire to look "pro" when I take photos its because of the amount of control you have over the photo. You can control the light so much more; you can control the exposure and the general aspects of the image. And with this freedom comes the choice of getting the clarity through the lens. To gain the ultimate freedom in picture clarity first of all you need to know what lens does what.
Fixed focal length lenses
A fixed focal length lens is a lens that is on most point and shoot and prosumer cameras. They are typically an average wide angle lens. It's kind of like a "mid range quality" lens. If you then take a zoom lens and compare the two, a fixed focal lens is smaller and often has a larger max aperture. This is good, because they work pretty well in low light situations. These lenses appear clearer than zoom lenses. The only problem here is that your person or subject can appear smaller than you would like without you move in closer.
And what of a zoom lens? Without going into overly technical details, zoom lenses often have more practical focal lengths for digital photography. They can give you a good angle perspective for filling the frame for example. These lenses are great if you need to take shots closer when it's impossible to get closer to something.
Optical zooms lenses are the best. My advice to you would be to forget digital zoom altogether. Digital zoom is not a real zoom, in other words it's not a true representation of what's there. You'll just get more noise on your image which can not really be edited.
The problem with zooms is that they loose light the closer you get. They have lower apertures and this can be difficult in low light conditions. In some situations it's possible to use the flash and have adequate lighting, but other times you use the zoom because you are far away from the subject and the flash is only effective a few meters away.
There is no general answer to "What lens should I get?" The answer is it depends on what your camera can do and what you want to do yourself. But the more you understand what lenses do what, the better off you are of making an informed decision and get the right lense for the job.