: what about those of us whose near vision isn't what it used to be?
: nothing wrong with my eyes, but my arms seem to be getting shorter

What you need here is a lens similar to those in reading glasses. these are rated in diopters, which are fractions of a meter. If the objest you wish to see clearly is located 1 meter from your eye, then you would want 1 diopter lens. Reading glasses would list this as either a 1.00 or a 100 strength lens.
For an object at 500 mm ( about 19 inches) you would want a 2 diopter lens. ( That would be 1000 mm divided by 2)

The process continues mathematically. If the compass is 125 mm (about 5 inches) from your eye then you would need a 1000/125 or 8 diopter lens to bring it into clear focus.

If, instead of getting reading glasses you want to buy a lens directly from some place like American Science and Surplus, look for one with a focal length equal to the distance the object is from your eye. (again, if it is 125 mm away, get a lens with a focal length of 125 mm. Plus or minus 20% to 30% would probably work.)

Those who have younger eyes with good eye muscles can probably focus fairly close without such assistance. Unfortunately, such things change with maturity.

hope this helps.

PGJ