You may well need a quality high-magnification loupe, but if you aren’t fortunate enough to find a bargain it can be worth considering what’s already around you and free. I use the end tube, with its front element, of a rubbishy old Tokina 400mm lens, which cost me nothing as the lens had no resale value. The tube is wide enough to encompass a 35mm negative on the light table, excludes distracting side light, has a huge eye relief, and magnifies easily enough to decide which negative to print. It’s far more pleasant to use than any loupe that has to be used close to the eye.