The wide slideshow is designed to crop the images to make sure they take up the entire size of the slideshow. If the uncropped images were used, there would be a lot of extra space since the slideshow is so wide.
With that said, here is some documentation on changing the settings for a slideshow: custom_slideshows.php
Maybe the slideshow dissolve would work better as a starting point since its not quite as side. You could use that as a starting point and use the guide above to remove anything you don't want showing up (thumbs, borders, etc).