It’s interesting to note that the earliest appearance of Grecian, in the 1840s, was in a condensed form. The full face version that inspired Hoefler & Frere-Jones’ steroidal Knox didn’t show up until nearly twenty years later.
A side by side comparison of two F’s – both came in a single case of type purchased last year from an eBay seller – illustrates how slight changes to a letterform can dramatically alter its presence. The character on the right has an elongated upper arm and a thinner central arm (or crossbar) with the addition of unbracketed serifs. These seemingly minor design changes make this F appear narrower and more refined.