How do you use the projector?
As a school teacher I found that most projectors had moderately crummy optics. My answer was to run the projector from my laptop. On the laptop, I would go into full screen mode. Didn't matter what the image was it filled the screen. This also gave me the option of zooming in on a detail, bringing up multiple images to compare etc.
If you have to bring the images to the club meetings on a thumb drive, then a careful crop (You probably want to do that anyway. People who don't need to crop have names like Ansel Adams) Now follow frank's advice and export with fit within.