Hi John,

There isn’t really such a thing as an ideal image size. It really just depends on a lot of things.

With a full width slider, the image might get rescaled (And with that less sharp) if it’s too small. It might get cropped if it’s too large and you really just can’t predict what size the screen will be of the person viewing your website. What you need to keep in mind is that larger images will equal sharper images (better quality) but also larger filesize (longer loading times).

It’s really all about balancing what you think looks good and isn’t too big a file for the user to load.

On our Champi demo we use 1950×850 which is really quite large in my personal opinion. As you can see, http://www.theme-dutch.com/presents/champi/ they are sharp.

Kevin