Aperture and light

I have read posts that say you get twice as much light from am f/2.8 lens than you do from f/4. How does this break down...all the way up to f/1.2. So do you get twice as much light in an f/2 as you do from an f/2.8? then from f/2 to 1.8 to 1.4 to 1.2.....
What is the formula. Not specifically this lens matchup but how much more light does a 85/1.2 get compared to a 85/1.8?
Thank you for any response.

thatkatmat wrote in post #3800892
I have read posts that say you get twice as much light from am f/2.8 lens than you do from f/4. How does this break down...all the way up to f/1.2. So do you get twice as much light in an f/2 as you do from an f/2.8? then from f/2 to 1.8 to 1.4 to 1.2.....
What is the formula. Not specifically this lens matchup but how much more light does a 85/1.2 get compared to a 85/1.8?
Thank you for any response.

light doubles with each FULL f-stop. check out an f-stop table.

ed rader

Thanks Ed, will do.
Hey Ed, you're all over both boards I browse and seems you've been shooting for a while. Did you go to school for Photography? I'm a Dad and a Manager at a Marketing office, I'm fortunate, the jobs not too demanding and really flexable. i was thinking of taking some classes on Photography, been shooting DSLR for about a year and it has become my passion. Any Ideas?

Basically, the halving of light is in multiples of the square root of 2. (divide 4 by sqrt(2) and you get 2.8, etc, etc.).

yeah, I was just checking a f-stop table and it was linked to all kinds of interesting topics on exposer. Thanks, very interesting.

thatkatmat wrote in post #3800937
Thanks Ed, will do.
Hey Ed, you're all over both boards I browse and seems you've been shooting for a while. Did you go to school for Photography? I'm a Dad and a Manager at a Marketing office, I'm fortunate, the jobs not too demanding and really flexable. i was thinking of taking some classes on Photography, been shooting DSLR for about a year and it has become my passion. Any Ideas?

hi Mat...i took a photojournalism class a looong time ago and was the editor of my JC newspaper. i later was a beat reporter for the local daily for about a year. i had the chance to use my AE-1 from time to time back then and got to do some darkroom work.

that was my previous experience with photography but i went the P&S route for many years until i became interested in digital photography a few years ago.

a lot of the old stuff still applies but there is much much more to learn these days. i think the main thing to learn is to filter out the stuff you don't need and concentrate on the stuff that will help your ability to take better pictures while keeping an open mind to new ideas and technology.

and i tell ya the older i get the harder it is to learn...or i should say to stay willing to learn .

my job's usually not to demanding either because i'm not debt driven and the boss doesn't like to work too hard -- i'm self-employed .

welcome!

ed rader

The formula is loosely based on the square root of two or about 1.4 so the "standard" f-stops are 1.4 to the Nth power or 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, etc. One f-stop admits twice as much light as the next higher number.

Thanks makes a lot of sense.
Ed, a long time ago someone suggested a few books, read one of them at the library, should have just bought it. Was thinking of taking some sort of class at a local J.C.
Decided right after I replied back about school that I should first buy those books, read them, and decide after I read them if school is the next step. I too am not as young as I used to be and school seems a bit daunting. But the goal is to advance my skills for now, so, I'll do what I need to do.
Thanks for the insight.....
Matt