2.8, 4, 5.6, 8, etc, what does it all mean???

[Ryguyinlj]

Ok, I know that the numbers in the title are indicators of F-stops. I know that each stop corresponds to twice as much light or vice versa. However, why are the numbers such? What do the numbers signify? Do the actual numerical values have any significance? How were they derived?

[mtbbrian]

Basically, those numbers are ratios. If you look on the front of the lens, you'll see 1:2.8 for the max f-stop.

Here is something I just found, that might help.
http://www.photo.net/bboard/q-and-a-...?msg_id=0001Om

Brian

[Dzerzhinski46]

When dealing with a circle, area does not double when you double the radius. A circle with a radius of 1 has an area of pi. A circle with a radius of 2 has an area of 4pi. If you remember your little stint in Geometry from highschool, or even junior high, you will remember that the area of a circle= pi (radius)^2 . So, as you rightly remember, each of the succeding numbers represents a circle with double the area. 1, 1.4, 2, 2.8, 4, 5.6, 8, etc. These numbers are progressions of the square root of 2. (square root of two)^0 is 1, (square root of 2)^1 is square root of 2 (approx. 1.4), and so on and so on. So the area of the circle doubles as the square root of 2. That is where those funny numbers come from. Did that make sense?

Dzerzhinski

[PhotoGimp]

HUH????? See what you did! Now I"M confused!

[DownByFive]

When dealing with a circle, area does not double when you double the radius. A circle with a radius of 1 has an area of pi. A circle with a radius of 2 has an area of 4pi. If you remember your little stint in Geometry from highschool, or even junior high, you will remember that the area of a circle= pi (radius)^2 . So, as you rightly remember, each of the succeding numbers represents a circle with double the area. 1, 1.4, 2, 2.8, 4, 5.6, 8, etc. These numbers are progressions of the square root of 2. (square root of two)^0 is 1, (square root of 2)^1 is square root of 2 (approx. 1.4), and so on and so on. So the area of the circle doubles as the square root of 2. That is where those funny numbers come from. Did that make sense?

Dzerzhinski

Too many....numbers...brain...overloading...

I'm a History and Political Science major...I've only taken one math class in fiv...er, four, years of college, so I'll take your word for it...