If you are using a rotating program on the front page of the website. It is necessary to crop your photos.
In general when you crop the photos, you will loose two-thirds of the photo.
(Note: Depending on the design of your website, the slideshow dimensions will be different. If you would like to crop your own photos, I can provide with the exact dimensions.)
Here is a normal photo from a standard camera phone.
As you can see, since this photo is a close up, it doesn't really work as a wide photo.