If you want to ensure that you print the entire image you see on screen (within a small margin of loss for the photo printing and paper cutting process), there are effectively three possible situations you will encounter for photographic prints on photo papers when using the Zenfolio configuration tool.
Case 1, Case 2: You may have an image of exactly the dimensions of the 'Product' or 'Featured Product'. In that case, you can have the print made with the image completely edge to edge and no white space at all OR you can manually using the configuration tool add white space around the image. Case3: The third situation arises when an image is of odd dimensions and you must accept white space around the image in order to not crop the image.
Case 4: If you want to adjust and crop the image yourself for printing on photo paper, you can avoid white space with even an odd sized image, but you will lose some of the image. That can be fine, if you want to zoom in on a portion of an image because that is the part of the image that you feel you would like to turn into a print instead of the entire image. It is your choice - as you are the one who is making the decision not me!
Case 1: Edge to Edge printing of Full Image
Case 2: Adding white space around a Full Image
Case 3: Mandatory white space when printing a Full Image