"dennis@home" wrote in message
...
On 27/08/2019 17:22, Bert Coules wrote:
They do look intriguing. I use and like varifocals but there are times
(and in differing circumstances) where they're not ideal and a single
prescription pair would be better. These might fit that bill.

IIRC they showed something similar on tomorrows world a long time ago.

my SLR camera from about 1980-something had an adjustable lens on the
viewfinder,

so the technology has been in commercial use for ages

tim