This app is designed to let you see just what focal lengths you use in the photos you capture. While it is far from feature complete, you should be able to point it to a folder containing photos and it will return a list of focal lengths for each photo that has a focal length field in its metadata. This should be all raw files, in-camera processed jpegs, and any file exported from software that supports this metadata.
The app will walk through every photo in the folder you select, as well as traverse photos in any subdirectories that are contained within it. At the moment there is no real progress indicator other than to tell you it has started working and when it completes. If you have a lot of photos just be patient as it is cranking through a lot of data!
This is a very rough build, both with the interface and the code (literally bare bones), but it works. I thought I’d put it out there to get suggestions about what should be added before I clean things up.
Please note that this is a Mac app that should run on model running Mac OS X 10.4 and above. I will consider porting this to windows if there is a lot of interest.