any web- sites show lenses use with camera and example of photo...?

Here is a mini-tutorial I made myself to compare focal lengths. This is NOT a lens test or a camera test! It is merely intended to show the difference between various focal lengths. The camera was a Nikon D200 and the lens was the Nikon 18-200 VR lens. There is further explanation on the image itself. It would help if you click on "All Sizes" above the image.

http://www.flickr.com/photos/7189769@N04/476181737...

While you are there, you can click on the little tiny picture of my cat's face. This will take you to the rest of my Flickr site. Pretty much every photo tells what focal length was used for each picture. Bear in mind that, unless specified, this is the ACTUAL focal length and not the 35 mm equivalent. (The difference is illustrated in the first picture you saw.)

You can probably find a discussion on http://www.kenrockwell.com/ also. Or, go to ANY camera review on http://www.dpreview.com/ or http://www.steves-digicams.com/ and look for sample images. Either under or over the picture, you will see the particulars about that photo.

1) VR is worth it for the amateur user based on their ability to hold the camera steady. VR's worth increases as you shoot at longer focal lengths (which magnifies any shake your hands may have). VR's worth also increases when you are attempt to hand hold long exposures. 2) Sigma is 3rd party. Generally 3rd party lenses have less quality control than the official company lenses. Some users will have great luck get great copies of the 3rd party lens and then tout that 3rd party has the same quality as the Nikon / Canon lenses. Because you have a Nikon D40, the Autofocus (AF) system is in the body of the camera, and requires special lenses to make use of it. This severely limits your choice of lenses to Nikon AF-S lenses. Make sure whatever lens you buy, still supports the AF system on your D40 (unless you are looking to do manual focus on each exposure). 3) Expensive lenses have more elements, are larger, heavier so that they can support larger apertures (smaller fstop numbers). Essentially this equates to the ability to take non blurry pictures with either fast moving subjects or in low light conditions which is often the case when professionals need to take pictures (weddings, sporting events, to name a few). 4) Biggest bang for your buck! (I would highly recommend the Nikon 18-200). It isn't pro quality, but it will give you the most range (wide angle 18mm to telephoto 200mm) all in one lens. It costs about 600-700 bucks, but is worth it if you are going to use the range. If you dont need the long range, your 18-55 is just fine. Hope this helps! Good Luck!

It depends on the type of camera you have. I own a Fuji and get pleasure from entering the competition on their website where you get to see other pictures taken by other people using a range of different Fuji cameras from simple point and shoot to the professional models.

Kabaam! http://www.pbase.com/cameras

select camera brand, then select model. Thousands upon thousands of sample images taken by certain lens models/camera models.