What is the difference between "Aperture" and "F-Stop"
 

In looking at the EXIF headers of my pictures, I notice separate entries
for "Aperture" and F-Stop". Sometimes these entries are the same, and
sometimes they are different. I have tried looking it up in several
glossaries, but haven't found anything that really explains the
difference.

Thanks, Gary

--
Gary Edstrom <gedstrom@pacbell.net>
Visit my Midway Island home page at http://gbe.dynip.com/Midway
My reality check bounced!
The above tagline is number 328 in a series of 547. Collect them all!

Re: What is the difference between "Aperture" and "F-Stop"
 

Gary Edstrom wrote:

> In looking at the EXIF headers of my pictures, I notice separate entries
> for "Aperture" and F-Stop". Sometimes these entries are the same, and
> sometimes they are different. I have tried looking it up in several
> glossaries, but haven't found anything that really explains the
> difference.

F stop and aperture are essentially the same thing.. The aperture is
measured in stops. The more stops, the smaller the opening.

Many cameras have duplicate fields in the EXIF info.. For example, my
Canon 10D has both "Exposure Time" and "Shutter Speed".

I don't know why they do this :) I'm guessing it's done to maintain
backwards compatibility with earlier EXIF standards.

Re: What is the difference between "Aperture" and "F-Stop"
 

Gary Edstrom wrote:

> In looking at the EXIF headers of my pictures, I notice separate entries
> for "Aperture" and F-Stop". Sometimes these entries are the same, and
> sometimes they are different. I have tried looking it up in several
> glossaries, but haven't found anything that really explains the
> difference.


Aperture is the diameter of the opening, f/stop is aperture divided by
focal length.

But I think what you are looking at is "maximum aperture of the lens"
and "f-stop used for this photo".


--
Paul Furman
http://www.edgehill.net/1
san francisco native plants

Re: What is the difference between "Aperture" and "F-Stop"
 

Aperture and F-Stop are fundamentally the same i.e. the higher the number the
smaller the lenz diaphragm inside the lens.

I believe what your seeing is the actual lenz aperture and the aperture setting
depicted at the cameras end. your camera may have a different reading than your
lenz may represent. lenz aperture will be the true aperture!

--
There are no words that can be heard unless someone listens....
Remove *flaps* to reply

"Gary Edstrom" <gedstrom@pacbell.net> wrote in message
news:qbkt7112vboacpt02ok9r9n73ueo8qejf3@4ax.com...
> In looking at the EXIF headers of my pictures, I notice separate entries
> for "Aperture" and F-Stop". Sometimes these entries are the same, and
> sometimes they are different. I have tried looking it up in several
> glossaries, but haven't found anything that really explains the
> difference.
>
> Thanks, Gary
>
> --
> Gary Edstrom <gedstrom@pacbell.net>
> Visit my Midway Island home page at http://gbe.dynip.com/Midway
> My reality check bounced!
> The above tagline is number 328 in a series of 547. Collect them all!

Re: What is the difference between "Aperture" and "F-Stop"
 

Another way to explain is:
aperture vs. f-stop is like
length vs. inches

"Gary Edstrom" <gedstrom@pacbell.net> wrote in message
news:qbkt7112vboacpt02ok9r9n73ueo8qejf3@4ax.com...
> In looking at the EXIF headers of my pictures, I notice separate entries
> for "Aperture" and F-Stop". Sometimes these entries are the same, and
> sometimes they are different. I have tried looking it up in several
> glossaries, but haven't found anything that really explains the
> difference.
>
> Thanks, Gary
>
> --
> Gary Edstrom <gedstrom@pacbell.net>
> Visit my Midway Island home page at http://gbe.dynip.com/Midway
> My reality check bounced!
> The above tagline is number 328 in a series of 547. Collect them all!

Re: What is the difference between "Aperture" and "F-Stop"
 

Paul Furman <paul-@-edgehill.net> writes:

> Gary Edstrom wrote:
>
>> In looking at the EXIF headers of my pictures, I notice separate entries
>> for "Aperture" and F-Stop". Sometimes these entries are the same, and
>> sometimes they are different. I have tried looking it up in several
>> glossaries, but haven't found anything that really explains the
>> difference.
>
>
> Aperture is the diameter of the opening, f/stop is aperture divided by
> focal length.
>
> But I think what you are looking at is "maximum aperture of the lens"
> and "f-stop used for this photo".

I'm sure it varies a lot by camera. With my Fuji S2, I get:

ExposureTime: 1/125
ShutterSpeed: 1/125
ShutterSpeedValue: 1/128

Aperture: 13.0
ApertureValue: 13.5
FNumber: 13.0

(actual values from my photo at
<http://www.dd-b.net/perl/picpage/dd-b/SnapshotAlbum/data/2005/05070-MCPPA-rally?id=ddb%2020050507%20010-029;IPTC=no;EXIF=raw>).

I'm interested in the pattern of two the same, one slightly different,
with the different one having the word "value" in the name. But I
don't know what, if anything, it means.
--
David Dyer-Bennet, <mailto:dd-b@dd-b.net>, <http://www.dd-b.net/dd-b/>
RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/>
Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/>
Dragaera/Steven Brust: <http://dragaera.info/>

Re: What is the difference between "Aperture" and "F-Stop"
 

Jim Townsend wrote:
> Gary Edstrom wrote:
>
>
>>In looking at the EXIF headers of my pictures, I notice separate entries
>>for "Aperture" and F-Stop". Sometimes these entries are the same, and
>>sometimes they are different. I have tried looking it up in several
>>glossaries, but haven't found anything that really explains the
>>difference.
>
>
> F stop and aperture are essentially the same thing.. The aperture is
> measured in stops. The more stops, the smaller the opening.
>
> Many cameras have duplicate fields in the EXIF info.. For example, my
> Canon 10D has both "Exposure Time" and "Shutter Speed".
>
> I don't know why they do this :) I'm guessing it's done to maintain
> backwards compatibility with earlier EXIF standards.

Moreover, they aren't always exactly the same, at least on my camera.


--
Ron Hunter rphunter@charter.net

Re: What is the difference between "Aperture" and "F-Stop"
 

Ron Hunter wrote:

> Jim Townsend wrote:

>> Many cameras have duplicate fields in the EXIF info.. For example, my
>> Canon 10D has both "Exposure Time" and "Shutter Speed".
>>
>> I don't know why they do this :) I'm guessing it's done to maintain
>> backwards compatibility with earlier EXIF standards.
>
> Moreover, they aren't always exactly the same, at least on my camera.
>

Yes, I've noticed that too.. But they are usually very close.

It seems at least one value is the 'raw' value (with decimal places) and
the other is nicely rounded.

Re: What is the difference between "Aperture" and "F-Stop"
 

Ok, I think I have found the answer to my own question:

And it involves MATH!

Take the square root of 2.

Raise it to the power of the aperature.

The result is the F-Stop.

I have tried this on several of my pictures and it works very precicely.

Example: Aperture=6.9189 F-Stop=11

(Sqrt(2))^6.9189 = 11.00014

I have tried it on other pictures and it seems to work.

On Mon, 09 May 2005 02:59:22 GMT, Gary Edstrom <gedstrom@pacbell.net>
wrote:

>In looking at the EXIF headers of my pictures, I notice separate entries
>for "Aperture" and F-Stop". Sometimes these entries are the same, and
>sometimes they are different. I have tried looking it up in several
>glossaries, but haven't found anything that really explains the
>difference.
>
>Thanks, Gary

Re: What is the difference between "Aperture" and "F-Stop"
 

The problem is that there ate 2 kinds of aperture!

Linear aperture is the size of the opeinging that the light passes
throught.
Relative aperture is F/stop which is focal length divided by linear
aperture.

Astronomers use aperture (casually) to mean linear aperture
Photographers use aperture (causually) to mean F/stop