Re: loupes for large format camera use and; humidity levels

If you don't mind looking like the biggest geek in the field, you can
use a binocular magnifier visor. There are a few brands with lots of
replacement lenses and they are very flexible. One problem with them
is that the maximum magnification is limited, but for focusing, only
moderate mag is needed so there is no problem. (When I spot prints,
they are too low magnification to my taste.)

--
Ryuji Suzuki
"Well, believing is all right, just don't let the wrong people know
what it's all about." (Bob Dylan, Need a Woman, 1982)