Fractional diopter closeup lenses?

Hi All -

I'm looking for very weak closeup lenses, something like 0.5 or 0.3 diopter (two or three meter focal length). I recall seeing them years ago at places like B&H but no more. They never were especially common. Any help?

I wonder if they might not be available (unmounted) from ophthalmic supply houses.

Edmund Scientific used to carry unmounted diopter lenses. Haven't seen their catalog in years.

I was going to ask the same question on another forum! For me 77 or 72 mm. Thanks!