Hi i am by no means a expert but i had a look at your image and that particular one is oblong so i think you are going to struggle with that particular one. My suggestion to you is to try and make you photo's square and all the same diameter to start with. If you look in your store settings all of the image sizes no matter what the size you will see that they are square in size. The problem with this is if you have a oblong object you will always have a area where there is no product due to the products shape. If your product fills the entire photo area then you will not have any white when you zoom. Hope this makes sense and helps some.