Author  Thread 

09/11/2002 09:02:52 PM · #1 
Part 1:
If you have your camera's aperture set at F11 and you change it to F5.6, how many F stops is this difference?
Part 2:
How much larger/smaller is the aperture at F5.6 than at F11?
PS If you know this one already, please don't answer... it will be a good learning experience for someone :)



09/11/2002 09:15:15 PM · #2 
I could figure out the fstops with my camera's manual control, but I don't know how to answer the second queston. Do break your lens and use a ruler? ;) 


09/11/2002 10:05:18 PM · #3 
Well, my manual settings close to these figures are: 5.2 ; 5.8 ; 6.5; 7.3 ; 8.2 ; 9.2 ; and 10.3 According to my book each increment is 1/3 stop which converts to 2 1/3 stops. Each stop to a smaller number is twice as large as the previous. I would guess the f5.6 is 4 times the size of f11. Basically though, if I want greater dof I will need a smaller aperture. (larger number) Correct? 


09/11/2002 10:07:55 PM · #4 
Answer to part 1: 2 stops Answer to part 2: Aperture is 4 times wider at 5.6
sjgleah
Originally posted by jmsetzler: Part 1:
If you have your camera's aperture set at F11 and you change it to F5.6, how many F stops is this difference?
Part 2:
How much larger/smaller is the aperture at F5.6 than at F11?
PS If you know this one already, please don't answer... it will be a good learning experience for someone :)



09/11/2002 10:25:17 PM · #5 
both are correct......
the stops are:
2.0,2.8, 4.0, 5.6, 8, 11, 16, 22, and up from there....
Each stop either doubles or halves the size of the aperture :)
* This message has been edited by the author on 9/11/2002 10:24:21 PM.



09/11/2002 10:59:51 PM · #6 
Everything you wanted to know about fstops and more including why smaller apertures give a wider depth of field 
Camera Optics
This is also interesting, just ignore the 'allegorical theory on depth of field except as pure fiction see the above link for a relatively simple explanation, but the sweet spot infomation is interesting and useful 
FStop? What's that? 


09/11/2002 11:47:34 PM · #7 
Actually, each stop doubles the light, but the diameter increases by the square root of 2. So, the size diameter doubles every two stops. The f stop is the focal lenght divided by the diameter of the opening, so in order for the number f/stop to halve (like F4 to F2, it would take two f/stops or F11 to F5.6). The area doubles at each stop, and thus the light, due the the pie times radius squared formula for area, doubles.
The diameter is twice as large at F5.6 as F11, not 4 times. Four times would be F2.8.
Look out, engineer here.
* This message has been edited by the author on 9/11/2002 11:47:12 PM.
* This message has been edited by the author on 9/11/2002 11:50:01 PM.



09/12/2002 06:08:57 AM · #8 
Originally posted by Zeissman: Actually, each stop doubles the light, but the diameter increases by the square root of 2. So, the size diameter doubles every two stops. The f stop is the focal lenght divided by the diameter of the opening, so in order for the number f/stop to halve (like F4 to F2, it would take two f/stops or F11 to F5.6). The area doubles at each stop, and thus the light, due the the pie times radius squared formula for area, doubles.
The diameter is twice as large at F5.6 as F11, not 4 times. Four times would be F2.8.
Look out, engineer here.
Doubling the diameter is not the same is doubling the area of the opening. The area of the opening either doubles or halves with each stop...



09/12/2002 06:52:01 AM · #9 
For extra credit, why is the answer to part 1 important? I.e. why might you want to know that F11 is 2 stops different from F5.6?
Again if you know this one already, please don't answer... it will be a good learning experience for someone :)
Originally posted by jmsetzler: Part 1:
If you have your camera's aperture set at F11 and you change it to F5.6, how many F stops is this difference?
Part 2:
How much larger/smaller is the aperture at F5.6 than at F11?
PS If you know this one already, please don't answer... it will be a good learning experience for someone :)



09/12/2002 09:53:44 AM · #10 
If no one hits this one pretty soon, I may take a stab at it myself :)



09/12/2002 10:04:52 AM · #11 
There are many reasons you would want to know that there are 2 stops difference between f11 and f5.6. The most obvious one I can think of is if you want to change the shutter speed while keeping the same exposure. You'd need to know it was 2 stops, so you could adjust the shutter speed 2 settings over. 


09/12/2002 10:06:40 AM · #12 
Originally posted by BigSmiles: There are many reasons you would want to know that there are 2 stops difference between f11 and f5.6. The most obvious one I can think of is if you want to change the shutter speed while keeping the same exposure. You'd need to know it was 2 stops, so you could adjust the shutter speed 2 settings over.
Shutter speed 'stops' work similarly to aperture sizes. To compensate for a 2 stop aperture change, you have to either increase or decrease your shutter speed by a factor of 4...



09/12/2002 10:07:18 AM · #13 
so does that make me right then? :P it's early still....... 


09/12/2002 10:27:07 AM · #14 
I'm not exactly sure what he is looking for just yet... there are several issues that would make you want to know where the F stops are... another possibility is when using filters... I will just wait to see what he is looking for :)



09/12/2002 10:27:09 AM · #15 
I think we have a dilemma....
Someone asks a question  and kindly asks anyone who knows not to answer.. Sounds like a strange game to me :) 


09/12/2002 10:28:43 AM · #16 
The purpose in it is to allow those who may want to look it up the opportunity to do so...



09/12/2002 10:29:45 AM · #17 
Right, the area doubles with each stop by the pie r squared formula, so I guess it is a matter of samantics of what you mean by size. Most commonly, the size is refered to by the diameter, which doubles every two stops.
I really wanted to make sure that people understood that the area and also the light, doubles at each stop, but the diameter changes by the sqare root of two. The is why the f/stops are 1,1.4,2,2.8 and so on, and do not change by a factor of two for every stop, but a factor of 1.414.
Originally posted by jmsetzler: Originally posted by Zeissman: [i]Actually, each stop doubles the light, but the diameter increases by the square root of 2. So, the size diameter doubles every two stops. The f stop is the focal lenght divided by the diameter of the opening, so in order for the number f/stop to halve (like F4 to F2, it would take two f/stops or F11 to F5.6). The area doubles at each stop, and thus the light, due the the pie times radius squared formula for area, doubles.
The diameter is twice as large at F5.6 as F11, not 4 times. Four times would be F2.8.
Look out, engineer here.
Doubling the diameter is not the same is doubling the area of the opening. The area of the opening either doubles or halves with each stop...
[/i]
* This message has been edited by the author on 9/12/2002 11:06:31 AM.



09/12/2002 12:49:43 PM · #18 
Originally posted by Zeissman: Right, the area doubles with each stop by the pie r squared formula,
Pie r round. *Cornbread* r squared.
Terry



09/12/2002 01:10:25 PM · #19 
Dad? Is that you?
Originally posted by ClubJuggle: Originally posted by Zeissman: [i]Right, the area doubles with each stop by the pie r squared formula,
Pie r round. *Cornbread* r squared.
Terry [/i]

