Ok, so basically everything in photography can be expressed in

>>2934943
>stop is a ratio of 2
>twice or half
>measure mass by halves

>>2934943
Stops don't really have units. More accurately, stops are a dimensionless quantity.

Think of stops the same sort of way you think about percent, decibels, and radians.

>>2934943
bokeh

>>2934943
Your post has six stops of autism and 17 stops of faggotry.

>>2934943
Stops are used to express ratios between two numbers. They aren't used for "basically everything".

Examples:
Shutter speed, aperture and ISO can't be measured in stops. How many stops is 1/125 seconds? Or ISO 800?

>its another anon ponders dumb stuff instead of trying to get better at photography episode

>>2934989
All those things can be measured in stops, all that is required is choosing one value as reference.

If ISO 50 is the baseline, 100 is +1 stop, ISO200 is +2 stops, ISO400 is +3 stops and so on.

Stops are commonly used in shutter speed and aperture, but a universal baseline isn't convenient for them really, so the reference used is just your current setting.
At 1/50 sec, take it a stop in one direction to 1/25 or in the other to 1/100.

>>2934960
>measure mass by halves
not a complex equation by any means.
It's just 2^x. Take the log base-2 of any number and you get the number of stops it is.

The base measure of mass is 1 gram.
A 134 gram object would offhand be about 7 stops of mass. (with calc 7.06609)
"B-b-but that's not clean", system conversions aren't. 134 grams to 4.72671 ounces isn't at all cleaner either or to pounds.

>>2935187
>All those things can be measured in stops, all that is required is choosing one value as reference.

That was literally his first sentence.

>>2935190
it's a shame his second sentence is literally the opposite conclusion because he's an idiot.

>>2934943
i wish youd stops posting

>>2935210
...c-could I post a stop less often?

>>2935187
this
>"B-b-but that's not clean"
yes, but inverse square and light, also hypotenuse
but you already know that

File: 525px_F-stopScale.jpg (40KB, 525x138px) Image search: [Google]

40KB, 525x138px

>>2934943
jump to TIP #8
http://www.betterlight.com/events_owners09_tips.html

image related because i like to see how distance and aperture digits are effectively interchangeable...makes using a flash much easier to remember.

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File: zencover2.jpg (583KB, 595x1000px) Image search: [Google]

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>>2934943
>so my question is what kind of measurement can't be expressed in stops?
Quality

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>>2935331
>zen and the art of motorcycle maintenance
You have excellent taste in books.

>>2935280
Yep. That relationship is rather beautiful in how simple it is.

Intensity loss over distance uses distance squared.
Area of an aperture is the diameter squared.

This means 8 feet and F16 has the same exposure as 16 feet and F8. Lost 2 steps and gained 2 steps equally.

>>2935365

Ah, yes. That rare "freshman in college" taste. So refined.

>>2935679
>Area of an aperture is the diameter squared.
Well, no.
pi*r^2
...but yeah, is cool.

Actually, what IS the correlation that makes them match up like this?
Math persons?

>>2935681
In this day and age "freshman in college" are too busy fapping to milfs on motherless to read books

>>2935967
oh wait.. because both are essentially unitless ratios
But that still doesnt feel like a very satisfying..or quantified answer..

>>2935967
Actually yes, it is based on the squared diameter.
Since a lens has a F-number which is focal distance / DIAMETER of opening, the formula that talks about radius isn't useful.
It's (pi/4) multiplied by D^2.
A constant multiplied by a squared variable.

The light intensity is also to the power of two. It's just inverse when you're moving away from the light, some constant times (1/distance^2) instead of distance^2.
If you're moving towards the light, then inverse isn't needed, it's a different constant from the lens aperture but exact same formula of some C * (D^2)

https://en.wikipedia.org/wiki/Inverse-square_law

It really doesn't matter at all what the constant is.

50 * X^2 and 1000 * X^2, the constant doesn't matter for what proportion a change in the result is compared to the original.
In both cases doubling the variable increases the total outcome by a factor of exactly 4, no matter what the constant involved was.

That's how simple a single variable squared is.

If you want a more complex answer, it's a rate-of-change problem of year 1 differential calculus.
One of the basic formulas is "The derivative of a constant times a function is equal to the constant times the derivative of the function."

In example with constant being 5.
A: Derivative of 5x^2 = 5 * 2x = 10x
B: Derivative of 100x^2 = 200x.

If X is 2, then the total of formula A got doubled and the total of formula B got doubled. It doesn't particularly care what the constant was.

If X is 1/2, then 10(1/2) and 200(1/2) both get halved... again, constant didn't change halving from being halving.

If the formula we used for lenses was like F/something^3, then we'd would be incapable of doing the trick. But things are conveniently both using the power of 2.

>>2935988
Poster below you nailed it...log base 2 is why.

Also, aperture isn't without units. It's in mm/mm^2, which is a stupid unit so no one bothers using it.

>>2936270
Excuse me, log 2, not log based 2.

>>2936133
I never got my full dose of math, and no doubt my age hardened brain isn't helping with visualising that first paragraph.
I already understood the rest. But from where are pi/4 and D^2 derived/obtained?

>>2936270
> mm/mm^2
but it also works in any unit of measurement you want to use... i guess it what i mean.

>>2934943
Your mother has a weight of 200 lbs. when she had you her weight increased by a stop. When your dumbass was driving her crazy she developed a cocaine habit and her weight dropped two stops. How much does she weigh now?

>>2936133
Doh
pi/4*D^2 *IS* pi*r^2
ffffffffffff i thought you were pulling that out of somewhere else.
Every single time this happens I wonder if I would have found it any easier if I was learning math now, instead of 40 years ago. It sure as fuck is easier to find visualisations, examples, and discussions of everything now.

Still, I'm not seeing the relationship between distance and aperture any clearer.
(I'm writing that because about 10 seconds after I hit post it'll suddenly present itself to me in an epiphany facepalm moment... complete with diagram....hopefully)