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How do you pronounce the part in bold?

The camera has a 32mm lens with a maximum aperture of f/4.5.

ColleenV
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Sergey Zolotarev
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  • It's so much easier if it's written as F4.5. f/4.5 is actually f=1/4.5. I guess this is why the big F notation was invented. – user3528438 Jul 18 '22 at 12:53
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    It's not 1/4.5, it's focal length over 4.5 eg 32/4.5. Usually written with an italic [or latin small f with hook] ƒ or lower case f where italics are not available. Lenses are usually actually inscribed like a ratio, eg 1:4.5 rather than f/4.5 used in magazines/reviews etc. I have never seen capital F used in any authoritative reference. – DoneWithThis. Jul 18 '22 at 16:26
  • I've since discovered Canon use F4.5. I shoot Nikon who use f/4.5 in 'print' or 1:4.5 on the lenses themselves, so I'd never seen this before. – DoneWithThis. Jul 20 '22 at 10:35

2 Answers2

38

It is the "F stop" and this particular setting is called

eff four point five

It actually means "aperture is focal length divided by 4.5" and is explained in Photography Life.

This is the conventional pronunciation when talking about the "F stop" in photography.

If this was general mathematics or engineering, one would say

eff over four point five

Ben
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Weather Vane
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    @gonefishin'again. The OP asks how it is pronounced. Similar is for example 'Catch-22'. No-one says "catch hyphen twenty two." – Weather Vane Jul 17 '22 at 08:15
  • I've always pronounced the "over" but I'm not a photographer so I'm prepared to accept that people generally don't. However, it's not similar to not pronouncing a hyphen - the "over" means something (division) and omitting it changes the meaning. If I quote the electrical formula I=V/R as "I equals Vee Arr" (no over) then I've changed the equation to I=VR which is wrong. – Rodney Jul 17 '22 at 13:51
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    @Rodney the 4.5 stop is the same setting whether or not you say 'over'. There are not two different settings, one as 4.5 and one as 1/4.5. Omitting the 'over' does not create any confusion, as there would be if you say VR instead of V/R. Again, OP asks what people say, not what is scientifically correct. – Weather Vane Jul 17 '22 at 14:01
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    I have always heard f/4.5 pronounced as this answer says. Eventually, if it's not clear from the context what I am saying, I could say f stop (which happens rarely), but I would never pronounce over. – apaderno Jul 18 '22 at 07:06
  • (In the rare-to-nonexistent case where the entry pupil diameter actually was 4.5 times the focal length, instead of 1/4.5 times, this would be called "f/0.22", pronounced "eff zero point two two". But I've never heard of a production lens with an f-number below f/0.9.) – hobbs Jul 18 '22 at 12:54
  • @hobbs I don't know if 10 lenses are enough for a "production lens", but https://en.wikipedia.org/wiki/Carl_Zeiss_Planar_50mm_f/0.7 is among the fastest lenses in history. Used by NASA for the dark side of the moon, and by Kubrick for shooting candlelight scenes in Barry Lindon. – Eric Duminil Jul 18 '22 at 13:12
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    Here's an example of a famous photographer (Joe McNally) talking about flash, shutter speed and f-stops : https://youtu.be/7G_CYoPgKHs?t=130 . He pronounces "f/16" as "eff sixteen", "f/2.8" as "eff two point eight" or simply "at two point eight". – Eric Duminil Jul 18 '22 at 13:23
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It depends on what you mean by a maximum aperture

If you mean "a maximum absolute aperture" then eff over 4.5 is correct because d=f/4.5 indeed, note the small "f" here stands for the focal length.

Or if you mean "a maximum relative aperture" then eff 4.5 is correct, but should be written as "F4.5", note the big "F" and no slash.

user3528438
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    Do you have citations for this? - it's something i've never seen before. – DoneWithThis. Jul 18 '22 at 13:31
  • Hmm… Canon refers to their lenses as F4.5 rather than the f/4.5 adopted by Nikon et al. Starting to look like there's no single acceptable standard, just whichever a manufacturer prefers. – DoneWithThis. Jul 20 '22 at 10:33