My school is hosting a loupes fair in person, but due to social distancing we are only allowed a very limited time during the fair. I've been told to get the highest magnification I can afford, to get a light, and to get something that feels comfortable. I also wear glasses and do not wear contacts, so are there companies that have loupes that would accommodate for that?
Things to look for:
Magnification (3x minimum, too high, you get tunnel vision)
Working Distance (depends on how you work)
Field of View (get expanded field, want to see more)
Illumination (preferably high intensity light)
Bridge of the nose fit (If you don't have a prominent bridge, you want one that is comfortable, otherwise they will keep slipping)
Weight balance (is it front heavy, top heavy, balanced on the ear, does it destroy your ears?)
Prescription (which frames accept your rx, if any?)
Warranty (loupes can break easily, this is more word of mouth, because you can have warranty, but if the company is a PITA to deal with, don't go with them)
TTL or flip up or a TTL that flips up - I prefer TTL, I hate the idea of adjusting flip ups, seems like an IC issue and timewaster in terms of having to adjust. Flip ups are front heavy.
I'll add more, if I think of anymore things to look for. Not all loupes are the same.