How would you define a "stop"

[tirediron]

Okay, I'm in the middle of re-writing a lesson plan for a basic photography course. I need a one-line definition which describes a stop in the sense of it being the basic unit of measure for exposure (as it applies to aperture, SS, and ISO). I don't usually have a problem with words (yeah, yeah, I know! :er: ) but for some reason I can't come up with a good line.

What sentence would you use to explain the "stop" to someone who knows almost nothing about photography?

 

[Bram]

From what I remember, i'm probably wayyyy off in left field but i'll givei t a shot. Remember just from memory.

A "stop" is a unit of measure that co-ordinates and is in coordinance with aperture and ISO settings, which internally adjusts your shutter speed?

Trying to sound like I know what i'm saying. :greenpbl:

 

[Goontz]

Something like: In photography terms, a "stop" refers to the amount of light being allowed through the lens, to the sensor/film, usually controlled by the lens aperture. One stop, as a photographic measurement, is either doubling or halving the amount of light allowed through.

That's kinda rough and quick, but maybe a start?

 

[Stradawhovious]

An irritated Police Officer once told me that it was "the lack of forward momentum for at least two seconds".

That was an $80 lesson you just got for free.

Cherish it.

 

[Big Mike]

It's a doubling or halfing of the amount of light.

 

[tirediron]

An irritated Police Officer once told me that it was "the lack of forward momentum for at least two seconds".

That was an $80 lesson you just got for free.

Cherish it.

I might have to fit that in some how.

 

[Village Idiot]

From what I remember, i'm probably wayyyy off in left field but i'll givei t a shot. Remember just from memory.

A "stop" is a unit of measure that co-ordinates and is in coordinance with aperture and ISO settings, which internally adjusts your shutter speed?

Trying to sound like I know what i'm saying. :greenpbl:

Which you don't.

 

[tirediron]

It's a doubling or halfing of the amount of light.

Yes, BUT... how do I explain that as it relates to ISO? It's not what a stop does/affects so much that I need as what it "is".. ie Is it a unit of control, or...

 

[phiya]

I believe, as I understand it.

A stop is a unit of measurement used in exposure, in terms of ISO full stops are measured by doubling or halving ISO value.

 

[Goontz]

It's a unit of measurement, to quantify ratios of light. ISO, shutter speed and aperture are simply different ways to affect the same thing; the amount of light the camera "sees," and in turn, the exposure.

I don't know that you can, in a one-line definition, put it in terms relating to either ISO, shutter speed, or aperture. A "stop" is always the same thing. The others are different ways to control a "stop's" effect.

 

[Big Mike]

Yes, BUT... how do I explain that as it relates to ISO? It's not what a stop does/affects so much that I need as what it "is".. ie Is it a unit of control, or...

In stead of saying 'amount' of light...you could use brightness.

Double the ISO, the image gets twice as bright...by one stop. Half the ISO gives you an image that is half as bright....one stop.

I also teach a somewhat basic photography course, but rather than starting with the auto modes and working toward manual. We start in (and stay in) manual mode until the auto modes get a brief mention at the end.

So near the beginning of the course, when I'm explaining shutter speed, aperture and ISO...I can just say that 'one stop' from either of the variables, will make the photo twice as bright or half as bright.

Another way of explaining it, is to use EV values. Each stop is one EV (up or down). We have a chart/list of EV values and what they approximate in the visible world.

 

[Goontz]

In stead of saying 'amount' of light...you could use brightness.

Double the ISO, the image gets twice as bright...by one stop. Half the ISO gives you an image that is half as bright....one stop.

I also teach a somewhat basic photography course, but rather than starting with the auto modes and working toward manual. We start in (and stay in) manual mode until the auto modes get a brief mention at the end.

So near the beginning of the course, when I'm explaining shutter speed, aperture and ISO...I can just say that 'one stop' from either of the variables, will make the photo twice as bright or half as bright.

Another way of explaining it, is to use EV values. Each stop is one EV (up or down). We have a chart/list of EV values and what they approximate in the visible world.

:thumbup:

 

[MichiganFarts]

An irritated Police Officer once told me that it was "the lack of forward momentum for at least two seconds".

That was an $80 lesson you just got for free.

Cherish it.

Damn you. Too many smartasses to compete with around here.

 

[Robin Usagani]

ISO is easy to explain.. wait til they ask you why f/2.8 is not a full stop from f/1.4

 

[ClickAddict]

An irritated Police Officer once told me that it was "the lack of forward momentum for at least two seconds".

That was an $80 lesson you just got for free.

Cherish it.

Reminds me of this....

A police officer pulls over a man who ran a stop sign. Office comes over.
"Sir do you know why I'm pulling you over"
"No"
"You didn't stop at the intersection"
"But officer I slowed down. What's the big difference?"
At which point the officer, pulled him out of the car, began beating him with a stick and said;
"Would you like me to slow down, or stop?"
Lesson learned.