80/20 doesn't even make it remotely a spot meter a spot meter is 1 max 3 and doesn't take in account 20% outside information. If someone wants to do the Zone System he/she should invest in a good spot meter even in camera spot meters are not real spot meters.
The glass thing is a good point though if the OP wears glasses the F3HP would be the best choice even better than the F and F2.