Sometimes the term "panoramic merger" is misleading. Panoramic mergers don't have to be shaped like an ultra-wide "panoramic" in the traditional sense of that word. Many of my mergers have more normal aspect ratios, like the square "panoramic" above.
This image is a great example of why I love panoramic mergers. Here's a 50 megapixel image I created in 2012 with my 12 megapixel Nikon D700. I could have backed up a touch and created this image in a single frame with a really wide angle, but instead I used a 28mm right on the edge of the lake and captured two horizontal rows of RAW images to blend into this image.
Why go to all this work? The answer is all about resolution. I'm obsessed with image quality and I love to print my photos huge.
Look for my upcoming tutorial book on creating panoramic mergers from the simple to complex. I'll announce it's availability here on the blog as well as in my newsletter.