You can set in your Admin -> Upload Options the thesholds for photo sizes you wish. To have a smaller medium image you need to put in a medium theshold that you like say 600. You can save that change and then go to Admin -> Showphoto Options set the option to use the popup window for large images. You will then when you upload images you will have a medium image and then be able to click to view the large.
Last edited by Chuck S; October 1st, 2011 at 10:49 PM.