I have the $conf['image_use_longest_side'] = true; yet my images are ONLY scaled by the shortest side.

Whether I have the above item set to true or false.. it has no affect, it only scales by the shortest side.

Is it a PHP function (outside of zenphoto) perhaps that needs to be turned on on my end?

Thanks!

What theme are you using?

I could be wrong, but I believe that ZenPhoto will only use image_use_longest_side when using a theme function such as getAlbumThumb/getNextImageThumb/getPrevImageThumb/getImageThumb but if the theme uses any of the getCustom___ functions, that function can specify how to crop the image, so in that case, I don't think that ZenPhoto would use image_use_longest_side.