QUOTE(Guy85 @ May 22 2010, 11:12 PM)
I'm a real entry level. Anyone can tell me the different between 14-42mm lens and 20mm lens? I'm searching through google, but not much understand.
Hope that any expert here can help me with this...
Are you talking about Olympus or Panny 14-42mm?

Anyway, to make it simple for you to understand:
14-42mm f3.5/5.6
- More versatile, because of its zoom capability (can shoot wider too) - better if you shoot event or wildlife
- Larger and heavier
- "Slower", means even at maximum aperture (lower f-stop) your image will appear blur if there's subject movement
- More difficult to capture sharp image under low light situation
20mm f/1.7 a.k.a "pancake"
- Cannot zoom (it's a prime lens - means the focal length is fixed)
- Lighter and smaller
- Faster... handy if you shoot pets or kids at f/1.7 - image would be sharp even there's subject movement
- Image is sharper if you capture photo under low light situation (e.g. indoor)
- At maximum aperture (f/1.7), you can have more obvious background blurring effect (known as Bokeh), like this:

For me (I own both 14-45mm kit lens and 20mm prime), I use the zoom lens occasionally for landscape or event (when zooming is required), but I use the pancake most of the time because it's lighter and take sharper image.
This post has been edited by samurai1337: May 23 2010, 12:33 AM