Focal length increase

Sorry but that does not compute. The two sides of the comparison must be measured in the same units in order to produce a repeatable ratio. Strapping a tape measure around your waist to produce an estimated weight is just not acceptable. It might do for weight watchers but this is a serious forum where we demand absolute accuracy (Matt).

We could measure displacement, by dunking the lenses (or people) into a container of water and measureint how much water overlows the container.
Better yet, we could rig a platform to a latch triggered by a tartget, by hitting it with a softball, causing said lenses or people to fall into the container!
Woo-Hoo! math is fun!

Can we choose our own liquid? The ladies will no doubt go for asses' milk, or perhaps Chanel. I will, predictably, plump for being dunked in a barrel of Bowmore's.

But please leave the lenses out of it.

G

I'll go for a dunking in Guiness. With mouth wide open!!

There is no focal length increase. It's a crop factor!

Liam, indeed the operator need not be repeated for the numerator AND denominator, but as a whole, you forgot to square root the left...

If you guys were to dunk me to evaluate my actual volume, I would choose Sandeman Port as my medium of choice.