Archived from groups: rec.photo.digital (

More info?)

logiclips@yahoo.com writes:

> Thanks a lot for these answers.

>

> When you compute the FOV with the formula mentioned here

>

http/folk.uio.no/gisle/photo/crop.html#fov
> one has to multiply the result with 2, right?

Wrong. The formula is:

FOV = atan(D/2/f)

where "D" is sensor dimension and "f" is focal length of the lens.

The normal way to use this formula is to use the diagonal (the

distance in mm from the lower left corner of sensor to the upper

right corner of the sensor measured in millimeters) for the letter

"D". Because the diagonal stretches across the entire sensor,

the resulting angle is also for the entire sensor, so you don't

multiply with two.

> Is it because of the 2 directions from the center of the lense to

> the edge?

Again: this has /nothing/ to do with the width of the lens'

aperture. It is the dimension of the camera's /sensor/ you

subsitute for "D" in the formula:

> Is there only one FOV?

No - there are three: Across (diagonal), width (horizontal) and

height (vertical)

> I thought maybe there are two: for the horizontal and vertical

> direction because of the unsymmetric size of the sensor?

I computed FOV for the diagonal in my example, because I think that

is the most interesting datum. It also makes it simple to compare

the FOV of sensors with different aspect ratios.

If you want to compute the FOV across the sensor (horizontal

direction), substitute the /width/ of the sensor for the letter

"D" in the formula.

If you want to compute the FOV from top to bottom of the frame

(vertical direction), substitute the /height/ of the sensor for

the letter "D" in the formula given above.

--

- gisle hannemyr [ gisle{at}hannemyr.no - http

/folk.uio.no/gisle/ ]

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Kodak DCS460, Canon Powershot G5, Olympus 2020Z

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