[tech-3d] RE:f/stop calculation

["Elliot Burke" <elliot@xxxxxxxxxx>]

The aperture diameter is focal length/f# if  the aperture is located in
front of the lens, towards to object.
If it is between the lens and the focal plane, separated by a distance d,
then the aperture diameter is roughly d / f# .
Case 3: aperture is inside the lens: there is no simple formula for this
case.

Elliot Burke

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There are 3 messages in this issue.

Topics in this digest:

      1. f/stop calculation
           From: "Dennis M. Hanser" <dmhanser@xxxxxxxxxxx>
      2. Re: f/stop calculation
           From: Brian Reynolds <reynolds@xxxxxxxxx>
      3. Re: f/stop calculation
           From: "Dennis M. Hanser" <dmhanser@xxxxxxxxxxx>


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Message: 1
   Date: Wed, 19 Apr 2000 17:51:51 -0000
   From: "Dennis M. Hanser" <dmhanser@xxxxxxxxxxx>
Subject: f/stop calculation

Anyone have a reasonably accurate and reasonably easy way to
calculate the actual physical size of an f/stop?
In particular I am looking for the sizes in mm for a 100mm flat field
lens at f11,  f16,  f32, and f64.

Thanks in advance

Dennis M. Hanser

Member -- Detroit Stereographic Society




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Message: 2
   Date: Wed, 19 Apr 2000 14:32:13 -0400
   From: Brian Reynolds <reynolds@xxxxxxxxx>
Subject: Re: f/stop calculation

Dennis M. Hanser wrote:
> Anyone have a reasonably accurate and reasonably easy way to
> calculate the actual physical size of an f/stop?
> In particular I am looking for the sizes in mm for a 100mm flat field
> lens at f11,  f16,  f32, and f64.
>

aperture = focal_length / focal_ratio

If the lens has a 100mm focal length then the aperatures are as
follows:

focal_ratio aperture
----------- --------
11          9.0909
16          6.2500
32          3.1250
64          1.5625

--
Brian Reynolds                  | "Dee Dee!  Don't touch that button!"
reynolds@xxxxxxxxx              | "Oooh!"
http://www.panix.com/~reynolds  |    -- Dexter and Dee Dee
NAR# 54438                      |       "Dexter's Laboratory"


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Message: 3
   Date: Wed, 19 Apr 2000 16:40:00 -0400
   From: "Dennis M. Hanser" <dmhanser@xxxxxxxxxxx>
Subject: Re: f/stop calculation



Brian Reynolds wrote:



> aperture = focal_length / focal_ratio

> If the lens has a 100mm focal length then the aperatures are as
> follows:
>
> focal_ratio aperture
> ----------- --------
> 11          9.0909
> 16          6.2500
> 32          3.1250
> 64          1.5625

That's simple enuff

Thanks!

Dennis M. Hanser



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