Your home page slideshow is the first thing visitors see when coming to your website. This can also be replaced with a single photos, video, or slideshow of videos.
No matter what you choose, create a gallery specifically for the slideshow. The first item in the gallery used, determines the aspect ratio for what appears on the home page. Your best option is to crop all your photos to the same aspect ratio. The gallery thumbnail can be hidden from visitors so the gallery itself is never found. This video will show you how.