MkIII re-visited

[Peter Laidler]

But there's a problem. The free-standing isoprophyl or methylated spirit has air in it in much the same way as water does. After a week or so you will see an air bubble forming. You've got to do the same again - and again - and again for several times before the iso inside the bowl is totally free of air.

Yours is a VERY early Mk3 with a top filler (later side fill) and screw-down lens (later clamp-down).

Just be advised that there are several versions of the rotating bezel too. One type has a bronze spring around the circumference while others click on and are retained by some sort of magic.