Velocity Reviews > CCD size and focal length

# CCD size and focal length

itsperu
Guest
Posts: n/a

 07-06-2004
Is there anyway to calculate the angle of view for a digital camera,
given its focal length and CCD size? (Canon Powershot A40 datasheet
tells me its 5.4mm-16.4mm focal length & CCD size is 1/2.7")
Can I assume the CCD size to be the diagonal and calculate FOV? or how
do i calculate effective CCD area?
Also, can anyone guide me a (simpler ) way to use WIA or Canon SDK
to acquire just the FOV from the digicam?
Perumaal

jpc
Guest
Posts: n/a

 07-06-2004
On 5 Jul 2004 22:50:19 -0700, http://www.velocityreviews.com/forums/(E-Mail Removed) (itsperu) wrote:

>Is there anyway to calculate the angle of view for a digital camera,
>given its focal length and CCD size? (Canon Powershot A40 datasheet
>tells me its 5.4mm-16.4mm focal length & CCD size is 1/2.7")
>Can I assume the CCD size to be the diagonal and calculate FOV? or how
>do i calculate effective CCD area?
>Also, can anyone guide me a (simpler ) way to use WIA or Canon SDK
>to acquire just the FOV from the digicam?
>Perumaal

It's very simple triginometry. The light ray that goes thru the
center of the lens and hits the center of the ccd is the base of the
triangle, the lightr ray that goes thru the center of the lens and
hits the edge of the ccd is the second side and the top half of the
ccd is the third side. Given two of the sides you can calculate the
respective angles or lengths of the the third side.

jpc

David J Taylor
Guest
Posts: n/a

 07-06-2004
"itsperu" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Is there anyway to calculate the angle of view for a digital camera,
> given its focal length and CCD size? (Canon Powershot A40 datasheet
> tells me its 5.4mm-16.4mm focal length & CCD size is 1/2.7")
> Can I assume the CCD size to be the diagonal and calculate FOV? or how
> do i calculate effective CCD area?
> Also, can anyone guide me a (simpler ) way to use WIA or Canon SDK
> to acquire just the FOV from the digicam?
> Perumaal

Perumaal,

See here for information on sensor sizes:

<http://www.dpreview.com/learn/?/Glos...or_Sizes_01.ht
m>

The normal formulae apply.

The FOV will be in the EXIF header (somewhere) if you use JPEG. Can't
help with WIA or SDK.

Cheers,
David

Dave Martindale
Guest
Posts: n/a

 07-06-2004
(E-Mail Removed) (itsperu) writes:
>Is there anyway to calculate the angle of view for a digital camera,
>given its focal length and CCD size? (Canon Powershot A40 datasheet
>tells me its 5.4mm-16.4mm focal length & CCD size is 1/2.7")
>Can I assume the CCD size to be the diagonal and calculate FOV? or how
>do i calculate effective CCD area?
>Also, can anyone guide me a (simpler ) way to use WIA or Canon SDK
>to acquire just the FOV from the digicam?

The most accurate way to calculate FOV is get the actual pixel pitch of
the sensor from the EXIF header (all Canon cameras I've looked at store
this in every image). Multiply pixel pitch by the image width and
height and you get the actual dimensions of the light-sensitive area of
the sensor. Knowing the width and height of the sensor, and the lens
focal length, you can easily calculate field of view as

HFOV = 2 * atan(width/2/FL)
VFOV = 2 * atan(height/2/FL)

Using the "1/2.7" nominal size is less accurate, first because 2.7 is an
approximate number, and because it refers to an "inch" that's about 16
mm. So your sensor's diagonal is about 16/2.7 = 5.9 mm, but only
approximately. The pixel pitch from the EXIF data should be far more
accurate.

Dave

itsperu
Guest
Posts: n/a

 07-08-2004
(E-Mail Removed) (Dave Martindale) wrote in message news:<ccevut\$2q2\$(E-Mail Removed)>...
> (E-Mail Removed) (itsperu) writes:
> >Is there anyway to calculate the angle of view for a digital camera,
> >given its focal length and CCD size? (Canon Powershot A40 datasheet
> >tells me its 5.4mm-16.4mm focal length & CCD size is 1/2.7")
> >Can I assume the CCD size to be the diagonal and calculate FOV? or how
> >do i calculate effective CCD area?
> >Also, can anyone guide me a (simpler ) way to use WIA or Canon SDK
> >to acquire just the FOV from the digicam?

>
> The most accurate way to calculate FOV is get the actual pixel pitch of
> the sensor from the EXIF header (all Canon cameras I've looked at store
> this in every image). Multiply pixel pitch by the image width and
> height and you get the actual dimensions of the light-sensitive area of
> the sensor. Knowing the width and height of the sensor, and the lens
> focal length, you can easily calculate field of view as
>
> HFOV = 2 * atan(width/2/FL)
> VFOV = 2 * atan(height/2/FL)
>
> Using the "1/2.7" nominal size is less accurate, first because 2.7 is an
> approximate number, and because it refers to an "inch" that's about 16
> mm. So your sensor's diagonal is about 16/2.7 = 5.9 mm, but only
> approximately. The pixel pitch from the EXIF data should be far more
> accurate.
>
> Dave

Thanks a lot. I have to check out what is an EXIF header and how to
read the chunk from JPG. Thanks on the info for EXIF!
Perumaal.

Dave Martindale
Guest
Posts: n/a

 07-08-2004
(E-Mail Removed) (itsperu) writes:

>Thanks a lot. I have to check out what is an EXIF header and how to
>read the chunk from JPG. Thanks on the info for EXIF!
>Perumaal.

Irfanview will display the Exif header data.

Dave

itsperu
Guest
Posts: n/a

 07-10-2004
(E-Mail Removed) (Dave Martindale) wrote in message news:<ccip7a\$695\$(E-Mail Removed)>...
> (E-Mail Removed) (itsperu) writes:
>
> >Thanks a lot. I have to check out what is an EXIF header and how to
> >read the chunk from JPG. Thanks on the info for EXIF!
> >Perumaal.

>
> Irfanview will display the Exif header data.
>
> Dave

Thanks a ton. EXIF header by Tachabanaya (unofficial) was extremely
helpful, and I was able to write a reader in VC .NET in under a day
(considering that I knew just C++ but no VC .NET, the time length may
be justified !)
It works perfectly now.
Thanks Dave!
Perumaal.