aperture size - quick basic question

[reemas]

when they say stopped down, does that mean a smaller hole, or a smaller f stop number (a larger hole).
and when the say a bigger f-stop, does that mean a larger number / smaller hole?

[Pekka]

"Stopped down" means bigger f-number (smaller aperture).
"Bigger f-stop", I would understand it as bigger f-number (smaller aperture).

f4 ---> f8 = "one stop slower" i.e. stopping down the aperture
f2.8 ---> f2 = "one stop faster", i.e. opening up the aperture
"fully open", "wide open" = smallest aperture number on the lens, i.e. largest aperture hole available

[FlyingPete]

Stop down does mean smaller hole which is a smaller aperture, but is a larger F-Number.

i.e. f/1.8 is a larger aperture than f/8, f1.8 is a bigger opening than f/8.

[glangston]

when they say stopped down, does that mean a smaller hole, or a smaller f stop number (a larger hole).
and when the say a bigger f-stop, does that mean a larger number / smaller hole?

Stopped down is smaller hole, and larger f-stop number. Opened up means larger aperture and smaller f-stop number.

f/1.4 is wide open aperture allowing the most light
f/22 is stopped down allowing less light

[dphoto]

I don't know who "they" is, but if it's me, then here's my answer: stopping your lens down means making the hole smaller; "Bigger f-stop" means making that f-number bigger, which also means making the hole smaller. My general rule is, when in doubt, clarify! :D

Now, if someone else has a different answer, then my general rule really applies: when in doubt, clarify!

-Deva

[Skip Souza]

Just who the hell came up with a system that uses bigger numbers for smaller holes, anyway???

[eosster]

Just who the hell came up with a system that uses bigger numbers for smaller holes, anyway???

Mathematics, lol.

[Chazs]

Mathematics, lol.

I think Mother Physics (AND meddling mathematicians are both to blame.) Here is a fairly good explanation of f-stop:

http://www.uscoles.com/fstop.htm

[Skip Souza]

I think Mother Physics (AND meddling mathematicians are both to blame.) Here is a fairly good explanation of f-stop:

http://www.uscoles.com/fstop.htm

This just keeps getting funnier.
Chazs, I visited the site you listed. It was clear as mud but it covered the ground. Thanks.
Any time you express something as a ratio like f stops it will always look backwards.
For conversation perposes and to avoid confusion we should speak of opening up or closing down (green for St Patty's Day) the aperture rather that stopping up or down, this should eliminate confusion.
Of course using the 'stop' word sounds soooo much more professional.

[FlyingPete]

Just who the hell came up with a system that uses bigger numbers for smaller holes, anyway???

I think the numbers officially do get smaller, as they are actuall fractions, i.e. f/8 is really 1/8, or something like that. I know f/1 is an opening the same size as the focal length, so is f/8 an opening 1/8th of the focal length?

[DaveG]

when they say stopped down, does that mean a smaller hole, or a smaller f stop number (a larger hole).
and when the say a bigger f-stop, does that mean a larger number / smaller hole?

Stopped down is indeed a smaller hole with a bigger number. So why the bigger number for the smaller hole? It's simple. You know that shutterspeeds like 125 or 250 are really 1/125 or 1/250. They're written as 125 because there's ususally not enough room to write the 1/XX.

Well apertures with their f stop numbers: 4, 5.6, 8 and so forth are really RATIOS. They should be written 1:4 1:5.6 1:8 but there isn't room. Now all of a sudden you can see the numbering makes sense. Of course 1:8 is smaller than 1:4. Yet the only place on a lens that you'll ever see the aperture numbers written as a ratio is on the end of the lens where they tell you the focal length as in Canon 50mm 1:1.4 Go have a look.

With shutterspeeds photographers talk about 125 all of the time but they will also refer to it as 1/125. No one talks about f-stops as as ratios because no one else knows this. Now you and I know so lets keep this our little secret and be superior. Everyone else ignore this please.

[Tom W]

"Stopped down" means bigger f-number (smaller aperture).
"Bigger f-stop", I would understand it as bigger f-number (smaller aperture).

f4 ---> f8 = "one stop slower" i.e. stopping down the aperture
f2.8 ---> f2 = "one stop faster", i.e. opening up the aperture
"fully open", "wide open" = smallest aperture number on the lens, i.e. largest aperture hole available

Don't forget f/5.6. :)

[Tom W]

Just who the hell came up with a system that uses bigger numbers for smaller holes, anyway???

Somebody that knows that the f-stop is the focal length divided by the aperture opening.

[markubig]

"Stopped down" means bigger f-number (smaller aperture).
"Bigger f-stop", I would understand it as bigger f-number (smaller aperture).

f4 ---> f8 = "one stop slower" i.e. stopping down the aperture
f2.8 ---> f2 = "one stop faster", i.e. opening up the aperture
"fully open", "wide open" = smallest aperture number on the lens, i.e. largest aperture hole available

So what are the full f-stops starting from 2.0?

f/2.0, f/2.8, f/4.0, f/8, f/????????????

i'm in bed and my camera is downstairs . . . just too lazy to get it and figure it out.

:o :o :o

[prime80]

So what are the full f-stops starting from 2.0?

f/2.0, f/2.8, f/4.0, f/8, f/????????????

i'm in bed and my camera is downstairs . . . just too lazy to get it and figure it out.

:o :o :o

f/1, f/1.4, f/2, f2.8, f/4, f/5.6, f/8, f/11, f16, f/22

These are the typical full stops

[markubig]

f/1, f/1.4, f/2, f2.8, f/4, f/5.6, f/8, f/11, f16, f/22

These are the typical full stops

Thanx Prime!!! So with my 50/1.8, when I go from f1.8 to f2, am I only moving a 1/2-stop?

[reemas]

is f/22 as small as it gets? i read on canon's website that the rebel xt supports up to f/90.

[robertwgross]

The f-numbers can keep on going, but it gets around the end of practicality.

Some lenses go to f/22. Some go to f/32.

F/64 has historical significance.

F/90 is a little extreme.

---Bob Gross---

[prime80]

Thanx Prime!!! So with my 50/1.8, when I go from f1.8 to f2, am I only moving a 1/2-stop?

That would actually be 1/3 stop.

Take a look at this list to see 1/3 stop increments:

(http://www.uscoles.com/thirdstops.pdf)http://www.uscoles.com/thirdstops.pdf