Hello from Canada, first post here. I recently bought an older Bausch and Lomb stereo microscope with a moveable base for a price that was too good to refuse. It came with 10x eye pieces and currently the space between the scope and an object in focus is about 3 inches - I’m assuming that’s called the focal length. My question is if I replace the 10x eye pieces for 5x would I increase the focal length? Because I have not engraved anything with a scope I’m not sure what the proper working distance should be. Thanks in advance!