This problem has been consistent and doesn't seem to change, no matter which approach I take. I've been looking extensively on this forum and elsewhere about how to get shadowbox to work with iframes. I've tried looking at these threads for help:
Several people post different solutions to the problem of getting an image to show up in shadowbox, instead of just linking to the full-scale image. Apparently the solutions have worked for other people, but I'm no programmer and it just seems a little overwhelming to try and decipher which one to do.