You know the ones I mean... The letters that come after the word "Nikkor" on the front of the older lenses. "Nikkor-P" "Nikkor-O" "Nikkor-Q" and so on...Ever wonder what they were for?

The answer is, those letters tell you the number of elements that particular lens contains. How? Ah well, theres the rub...

You have to have at least a passing acquaintance with Latin to decipher the code, because those letters are the first letter of the latin word for the number of elements that the lens contains.

"Huh?" I hear you saying, (and that reaction is probably the reason that Nikon ceased to designate their lenses like this.)

Some bright spark at Nikon, who had obviously benefited from a classical education, came up with this cunning plan. (Actually I'm being unfairly facetious; before the company manufactured cameras, they made optical instruments for the medical field, where Latin terms are fairly commonplace...)

Anyway,  the idea was that the letter on the front of the lens would tell the user how many elements were in the lens:

U (Uns) = one element

B (Bini) = two elements

T (Tres) = three elements

Q (Quatuor) = four elements

P (Pente) = five elements

H (Hex) = six elements

S (Septem) = seven elements

O (Octo) = eight elements

N (Novem) = nine elements

D (Decem) = ten elements

Most people never understood what these letters meant, and even fewer people cared (lets face it, very few people who are using a lens actually want or need to know how many elements it contains!) Consequently, Nikon discontinued the practice by 1974.

So, today those letters tell us something else, if you see a lens with a letter after the word "Nikkor" you know it was produced before 1974. A handy rule of thumb/rough guide, without having to look through tables and charts of serial numbers.

By the way, if you see something like "Nikkor-H-C" the "C" tells you the lens has coating to reduce reflection, and thus improve light transmission....

One final, unrelated thought... you may have noticed that if you were to add "ber" to the final four latin words in the list, you get the last four months of the year. However, those months are NOT the seventh through the tenth months of the year, but rather the ninth through the twelfth. The reason being that the Romans, having named the months of the calendar for us, then messed it up by making two new months in the summer, and named them for the Caesars, Julius (July) and Augustus (August) ...So, given that degree of forethought, it's hardly surprising that their empire went into decline...sorry, being facetious again there....