I took several test shots with two different bodies and I'd like to compare the results side by side a la DPReview's studio scene tool. Specifically, I'd like to zoom them up to 100% size with the ability to pan around the images while keeping the views in sync. I have Lightroom 5 but the comparison view only zooms to ~50% unless I am overlooking some setting. I also have Photoshop. I'm looking for a free Mac or web app if the other two won't do it for me.