Transforming several pictures and joining them into one has never been easier, STOIK PanoramaMaker lets you open any folder so you can choose which pictures to work with. You just have to choose the photographs, place them on the upper part of the interface, and hit Start Stitching.
STOIK PanoramaMaker can create panoramic images with angles as wide as 360º, but you can always choose the focal length you think is appropriate, in order to avoid any distortions. This is the only thing you have to decide, the rest is done automatically.
This utility stitches the images with different zoom levels; you just have to make sure all the pictures you use are in the same size.
Trial version works for 15 days.