Does anyone reading have something like these magnifying glasses and if so are they any good? I've got some which are similar to these but they have a very short focal distance so you need to be very close to what you're looking at which is often impractical. A 320 mm focal distance would be more comfortable but, since you're further away from the subject, things will look smaller which makes me think 3.5x wouldn't be enough. Anything above 3.5x in the form of those compound lenses are very expensive. Alternatively there's those really big magnifiers that you don't wear.

 

Want to find out if they work? Go to a welding store and try the welding hood "cheaters". They usually have a display in the store that lets you try the different magnifications to see what works for you.