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So Chuck Goolsbee, friend and geek, has a fun button to push. Tell him your network speed is fast or slow and watch him go all pedantic and explain the difference between network speed, (there's one: c, aka the speed of light), and network bandwidth is how much data you can shove down a given network pipe type. But from a modem to 10G over fiber, it all moves at c. The truth is, he's right. Network speed is unchanging, bandwidth is not, and regardless of common usage, the two terms are not interchangeable. 300 million people in agreement can be, and often are, wrong.
So I see people on Twitter talking about lens speed, when they mean aperture. The spirit of Chuck rises..."Um...light is moving through that lens at the same speed no matter what. That lens is neither fast nor slow, since it's not altering the speed of light, (yes, I know c is the speed of light in a vacuum, but I've yet to see a lens advertising itself with "we alter the speed of light for better pics!", although it would be a neat trick), and since the shutter mechanism is (normally) not in the lens, the lens cannot be fast or slow."
Oh holy fucking shit, you'd have think I pissed on the cross, helvetica, and vi all at once. People start throwing Wikipedia definitions of lens speed at me, blah, blah, blah. (Note: when the definition of a "fast" lens is:
A lens with a larger maximum aperture (that is, a smaller minimum f-number) is a fast lens because it delivers more light intensity (illuminance) to the focal plane, allowing a faster shutter speed.That's wikipedia saying "we call it speed, but really, it's the amount of light the lens allows in, which allows you to use a faster shutter speed, so even though we use "fast", the lens isn't doing fuck all faster, you just are using that word wrong." Aperture is analogous to bandwidth. All lenses work at the same "speed"...that of light. The amount of light coming in the lens changes, and greatly, but that's bandwidth. It's all moving at the speed of light.
300 million photographers are still wrong, even when they yell really loud.
Fuckin' Goolsbee.
Like I needed to be more pedantic.
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Chuck Goolsbee, Pendanticism, Speed is not bandwidth
Posted by John C. Welch at 19:08 | Permalink
Comments
I see you and Mr. Goolsbee as two sides of the same Michael Moorcock character. There are others. None of you are supposed to get along.
I'd be pleased to meet either of you. And you can piss on Helvetica all you want, because it's Frutiger that rules.
Posted by:
Moeskido 
|
February 19, 2008 8:49 PM
Only a nerd or geek can truly appreciate the finer points of pedantry. I think that you both fit the bill nicely. :)
Posted by:
PigInZen |
February 19, 2008 9:06 PM
I disagree actually. When people say the speed is faster, they mean more data arrives per second.
Take for example talking to a fellow person. You can say that person is talking fast if he is saying more words per minute than usual. The fast speaker still sends his information, or words, at the speed of sound, but there is more information travelling in that time.
Posted by:
matt2e |
February 19, 2008 9:07 PM
Oh it's just semantics. People use language poorly in all sorts of situations. Like this comment....ahem. Just want to know which lens to use to take a flickr-worthy photo of the lunar eclipse 2/20/08.
Posted by:
Seth Anderson |
February 19, 2008 9:08 PM
lol.
So then a "fast" lens is really just a "wide" lens... d'oh!
;)
--chuck
Posted by:
chuckgoolsbee |
February 19, 2008 9:12 PM
Speed isn't velocity, and the word really needs context for meaning.
In the context of network data throughput, we talk about bytes per second; in the context of cars we talk about kilometres per hour; in the context of rotation we talk about radians per second.
By the way, electrons don't move at anything close to the speed of light in a wire. They move at a rate of tens of metres per second. Transmission of electrons (as we understand it today) is more like a queue than a pipe. Now if you're talking about fibre optics, we're back to the speed of light (in glass) and everyone's happy.
Posted by:
GaryPatterson |
February 20, 2008 12:23 AM
Reminds me of The Big Lebowski:
'You're not wrong Walter. You're just an asshole.'
Posted by:
Tom Hillman |
February 20, 2008 4:54 AM
Actually Gary, it's bits per second, if you're talking about rated speeds of a given network type.
As well, the true speed of electrons through copper isn't a design feature, at least not in networks. You don't say "I'm going to use foo-gauge wire, because it slows the electrons down to bar speed." That's a side effect of the material, heat, impurities, etc. Given no resistance, the electrons will happily get as close to light as possible.
Now, if you show me a lens where the speed of light through the various elements is a design characteristic, and there are a number of such lenses where that speed is deliberately controlled to achieve a desired result, then I'll happily accede that you have a "fast" vs. a "slow" lens. But as used today? "Wide" vs. "Skinny" would be more correct.
Tom,
See, you really DO understand me. It's nice to see my hard work rewarded so kindly.
Posted by:
John C. Welch 
|
February 20, 2008 7:59 AM
Matt,
That's still a function of bandwidth. No matter how many words per second someone can clearly enunciate, the sound they emit is moving at the same speed. More data moving at the same speed = greater bandwidth. "more efficient" is probably a better descriptor of what we mean when we say "faster" with regard to networks.
Posted by:
John C. Welch |
February 20, 2008 8:01 AM
Naw, they're not wrong. They're just using the term differently - to refer, in fact, to an entirely different property of the network.
"Less time to do the thing" means "faster", the way people actually use English.
"The network is faster" does not, indeed, mean that the speed of a signal on it has changed; it does - quite correctly - mean that one can do what one needs "faster" using it than a "slower" one.
They simply are not speaking of the physical speed of the signal along the wire, so it's strange to complain that they aren't, when they aren't trying to and nobody (other than your friend?) thinks they're doing so.
(Also, calling a lens "wide" already refers to field of view - which even pedantically isn't wrong; the area represented on the film is a wider area, if one measured it - so to confuse aperture with "wide" or "skinny" is even worse than to call it "fast" or "slow".
A "fast" lens lets you expose the film in less time, ceteris paribus, and therefore the usage isn't wrong, even if you don't like it.)
Seth: Any lens you want, I reckon. Pretty much any lens can take a good photograph, especially if you're not talking macro. If you want to fill the frame, I suppose you'll want a relatively narrow lens.
(And possibly some 8x ND filter to slip over the eyepiece to not accidentally damage your retina while composing... at least you don't have to worry about focusing!)
Posted by:
Sigivald |
February 20, 2008 3:06 PM
Ooh now I get to be pedantic! Actually the speed of light is controlled to achieve a desired result in EVERY optical lens ever made. Evars. Otherwise they wouldn't be a lens at all. The refractive index of a material is based on the speed of light in that material. This, combined with the shape of the lens, determines how the lens functions.
Of course this doesn't go against your main point that these "fast" lenses just allow you to increase the shutter speed in a particular light condition compared to a "slow" lens. This also depends on the user to actually do that. In some cases a person might actually decrease the shutter speed to achieve a desired result.
Posted by:
Michael Krzyzek |
February 20, 2008 6:13 PM
(Re. as-yet-unposted comment:
Don't mind me, I was thinking "solar eclipse". For lunar, well, the moon follows the sunny F/16 rule, but when it's totally eclipsed, well, there's nothing to take a picture of, but some black.
And I don't think it lasts long enough to really expose the stars surrounding the "hole". Unless you have a Noctilux and some ISO 6400, I guess...)
Posted by:
Sigivald |
February 20, 2008 6:13 PM
