Ah, many thanks EnglishBob :)

I wondered if just upping the IOR would do it... thought that had to be the setting I needed to change... but it was the maths of that I was unsure about really I guess...

...e.g. if I had to increase the IOR, or invert it, or what.

I've made a nice morph to increase the thickness (or rather z-depth diameter) of the magnifying glass prop lens now too...

...so I will play around combining that "increase magnification" morph, with increasing the IOR.

Originally, I'd woken up with the notion that the lens of a magnifying glass was convex on one side and concave on the other! Which, of course, makes no sense, I don't think, in the real world.

It is Monday... this sort of thing seems to happen to my brain, on a Monday... ;)