Thumbnail Sizes

Hi all

I have set up a thumb image size for my blog as follows in the functions.php `add_theme_support( ‘post-thumbnails’ );
add_image_size( ‘new-thumb’, 800, 300, true );`

I have also added this in my index.php page <?php the_post_thumbnail('new-thumb'); ?>

the problem is that the image is only showing in proportion and not cropping the height, so what ever the height is of the image is then the width is in proportion and I would rather have a cropped image that uses the width as the main thing.

Hope that makes sense and thanks for your time