About terminology..

Ilmari Reitmaa · April 26, 2004

Even at the risk of nitpicking, here goes... :P

I wish to bring to your attention two constantly repeated terminological errors.

1. The unit of measure for thermodynamic temperature is kelvin, abbreviated K, not degrees Kelvin.

Historically, temperature was actually measured in degrees Kelvin, but degree was officially dropped already in 1967. See http://www1.bipm.org/en/si/base_units/kelvin.html for more information. Notice also that this renders terms like Mired (micro reciprocal degrees) rather dubious; I've sometimes seen the abbreviation MK^-1 used instead.

2. The abbreviation of prefix kilo is k, not K (as K is the abbreviation of kelvin)

Actually this is slightly more complicated and officially depends on the context (whether kilo is taken to be 1000 or 1024); however K is always incorrect, and while not necessarily official, the de facto abbreviation is k in all contexts (see http://physics.nist.gov/cuu/Units/binary.html for more information). Therefore, expressions like 4K and 5000KW are incorrect.

While terminological correctness is secondary to getting your point across, any use of incorrect terminology does tend to undermine the credibility of the context where it occurs, at least in the eyes of an outsider (here a non-cinematographer). As these mistakes frequently occur even on the pages of such esteemed publications as the American Cinematographer magazine and the ASC Film Manual (including the 8th edition), I would like to see them corrected someday.

Regards,

Ilmari Reitmaa

John Pytlak RIP · April 26, 2004

Thank you for the update. I'll remind our webmaster to follow the current SI protocol.

Phil Rhodes · April 26, 2004

Hi,

Let's not even get started on Kb, kB, KB and kb as abbreviations for multiples of either 1000 or 1024 bits or bytes, and indeed how many bits there are in a byte, word, long word, double, float, etc...

Phil