Focal length of digital camera lenses

wrote:

> Is there some universal standard for specifying the focal length of a
> digital camera lens that will allow one to calculate the angle of view of
> that lens?

Yes. It is called 'the metric system.'

> 35mm cameras have a standard frame size of 24 x 36mm, so, if you know the
> focal length of the lens, you will know the exact angle of view. Since the
> size of the active portion of a digital camera sensor is generally
> unknown, how can one determine the viewing angle?

The size of the active portion of a digital camera sensor is generally
*not* unknown. It's usually printed in the manual, along with angle of
view and 35mm equivalents focal lengths.
 >> Stay informed about: Focal length of digital camera lenses 

normanstrong DeleteThis @comcast.net wrote:
> Is there some universal standard for specifying the focal length of a
> digital camera lens that will allow one to calculate the angle of view of
> that lens? 35mm cameras have a standard frame size of 24 x 36mm, so, if you
> know the focal length of the lens, you will know the exact angle of view.
> Since the size of the active portion of a digital camera sensor is generally
> unknown, how can one determine the viewing angle?

This is precisely why nearly all point-and-shoots are marked with
"35mm-equivalent focal lengths". Despite many people railing against
the practice. It's the only way in any kind of common use to specify
what the range of views the camera will give you is.

Directly marking the range of angles of view would be the other approach
-- say "61 degrees - 10 degrees" or some such.
 >> Stay informed about: Focal length of digital camera lenses 

On Sun, 21 Jan 2007 10:47:35 -0800, wrote:

>Is there some universal standard for specifying the focal length of a
>digital camera lens that will allow one to calculate the angle of view of
>that lens? 35mm cameras have a standard frame size of 24 x 36mm, so, if you
>know the focal length of the lens, you will know the exact angle of view.
>Since the size of the active portion of a digital camera sensor is generally
>unknown, how can one determine the viewing angle?

Google it.

Or check the manual. If that doesn't give the angle of view, look up
the "equivalent focal length" compared to the 35mm frame and work it
out from there. If that isn't there either, then you need to determine
it by measuring what you get.

I am guessing that 99% of photographers don't know the angle of view
of their lenses.

KS
 >> Stay informed about: Focal length of digital camera lenses 

Sensor sizes are usually specified somewhere in the camera literature
(manual appendix, data sheet). It might be the actual active area in mms
width and height (DSLR's) or something like 1 / 1.8" for a compact. The
angle of view is defined as the angle covering the diagonal of the picture,
thus you have to calculate the diagonal if width and height are known or you
can directly convert a fractional size to the diagonal. Unfortunately the
fractional system is inherited from video equipment operating with video
tubes, the size gives the outer diameter of the video tube, with the active
significantly smaller (.633 times the outer diameter). To calculate the
diagonal in mms multiply the fraction with 0.633 and 25.4. Of course the
fractional measures are not accurate to the micron, but it should permit
you to do approximate calculations.

If you know who makes the sensor used in your camera you might be able to
find a datasheet on the manufacturer's website.

schrieb im Newsbeitrag

> Is there some universal standard for specifying the focal length of a
> digital camera lens that will allow one to calculate the angle of view of
> that lens? 35mm cameras have a standard frame size of 24 x 36mm, so, if
> you know the focal length of the lens, you will know the exact angle of
> view. Since the size of the active portion of a digital camera sensor is
> generally unknown, how can one determine the viewing angle?
>
> Thanks,
>
> Norm Strong
>
 >> Stay informed about: Focal length of digital camera lenses 

normanstrong DeleteThis @comcast.net wrote:
> Is there some universal standard for specifying the focal length of a
> digital camera lens that will allow one to calculate the angle of view of
> that lens? 35mm cameras have a standard frame size of 24 x 36mm, so, if you
> know the focal length of the lens, you will know the exact angle of view.
> Since the size of the active portion of a digital camera sensor is generally
> unknown, how can one determine the viewing angle?

I have a really cool little calculator for PalmOS that has presets for a number
of different standard frame sizes for video, photo and CCTV cameras, that will
tell you the FOV for any given focal length, as well as simple graphics
illustrating the FOV and the resulting view of an object at a given distance.
No idea if there's actually a Windows or MacOS version, but if you have a PalmOS
device, I can tell you where to find it
 >> Stay informed about: Focal length of digital camera lenses 

Matt Ion wrote:
> normanstrong.DeleteThis@comcast.net wrote:
>
>> Is there some universal standard for specifying the focal length of a
>> digital camera lens that will allow one to calculate the angle of view
>> of that lens? 35mm cameras have a standard frame size of 24 x 36mm,
>> so, if you know the focal length of the lens, you will know the exact
>> angle of view. Since the size of the active portion of a digital
>> camera sensor is generally unknown, how can one determine the viewing
>> angle?
>
>
> I have a really cool little calculator for PalmOS that has presets for a
> number of different standard frame sizes for video, photo and CCTV
> cameras, that will tell you the FOV for any given focal length, as well
> as simple graphics illustrating the FOV and the resulting view of an
> object at a given distance. No idea if there's actually a Windows or
> MacOS version, but if you have a PalmOS device, I can tell you where to
> find it

Oh yes, and the calculator uses the standard definitions specific to each
industry... I use it mainly for CCTV, where CCD sizes are specified by the
diagonal measurement of the sensor (1/4", 1/3", 1/2")... the CCTV selections are
all listed in those terms.

Very nice.
 >> Stay informed about: Focal length of digital camera lenses 

Paul Rubin wrote:
> if writes:
> > Not in mine. Panasonice describe it only as 1/2.5" which is 10mm.
>
> 1/2.5" means the sensor is the same size as the sensor in an old-style
> vidicon tube of diameter 1/2.5". The vidicon tube had a phosphor
> sensor sealed in a glass envelope, and 1/2.5" was the OUTSIDE diameter
> of the glass envelope. The sensor itself is about 60% of that, so the
> actual sensor is about 0.24" diagonal.

<http://www.dpreview.com/news/0210/02100402sensorsizes.asp>

They don't have 1/2.5" listed, but they do have 1/2" (a bit larger)
which is 6.4 x 4.8 mm with an 8 mm diagonal. I don't know what
"10 mm" means, because any possible dimension for a 1/2.5" sensor
is less than 10 mm.
 >> Stay informed about: Focal length of digital camera lenses 

This message is not archived
 >> Stay informed about: Focal length of digital camera lenses 

if writes:
> Not in mine. Panasonice describe it only as 1/2.5" which is 10mm.

1/2.5" means the sensor is the same size as the sensor in an old-style
vidicon tube of diameter 1/2.5". The vidicon tube had a phosphor
sensor sealed in a glass envelope, and 1/2.5" was the OUTSIDE diameter
of the glass envelope. The sensor itself is about 60% of that, so the
actual sensor is about 0.24" diagonal.
 >> Stay informed about: Focal length of digital camera lenses 

if wrote:

> usenet DeleteThis @mile23.c0m (Paul Mitchum) wrote:
>
> > The size of the active portion of a digital camera sensor is generally
> > *not* unknown. It's usually printed in the manual, along with angle of
> > view and 35mm equivalents focal lengths.
>
> Not in mine. Panasonice describe it only as 1/2.5" which is 10mm. However
> if the sensor was 10mm in size you would expect it's "28mm equivalent"
> lens to be 6.5mm but in fact it is 4.6mm, so clearly Panasonic are
> misrepresenting the size of the sensor in the specifications.

Not to be a jerk about it or anything, but are you sure you're reading
the figures correctly?
 >> Stay informed about: Focal length of digital camera lenses 

On Sun, 21 Jan 2007 19:57:42 GMT, Matt Ion
wrote:

>Matt Ion wrote:
>> normanstrong.DeleteThis@comcast.net wrote:
>>
>>> Is there some universal standard for specifying the focal length of a
>>> digital camera lens that will allow one to calculate the angle of view
>>> of that lens? 35mm cameras have a standard frame size of 24 x 36mm,
>>> so, if you know the focal length of the lens, you will know the exact
>>> angle of view. Since the size of the active portion of a digital
>>> camera sensor is generally unknown, how can one determine the viewing
>>> angle?
>>
>>
>> I have a really cool little calculator for PalmOS that has presets for a
>> number of different standard frame sizes for video, photo and CCTV
>> cameras, that will tell you the FOV for any given focal length, as well
>> as simple graphics illustrating the FOV and the resulting view of an
>> object at a given distance. No idea if there's actually a Windows or
>> MacOS version, but if you have a PalmOS device, I can tell you where to
>> find it
>
>Oh yes, and the calculator uses the standard definitions specific to each
>industry... I use it mainly for CCTV, where CCD sizes are specified by the
>diagonal measurement of the sensor (1/4", 1/3", 1/2")... the CCTV selections are
>all listed in those terms.
>
>Very nice.

I have a Palm OS device.
Can I impose on you to provide the link?


--
Jesse Jackson said Thursday
it's all but certain he will
endorse Barack Obama for
president. Let the bidding begin.
Barack Obama has already offered
ten million dollars and a cabinet
post if he will endorse Hillary
Clinton instead.
 >> Stay informed about: Focal length of digital camera lenses 

"David Dyer-Bennet" wrote in message

> normanstrong.TakeThisOut@comcast.net wrote:
>> Is there some universal standard for specifying the focal length of a
>> digital camera lens that will allow one to calculate the angle of view of
>> that lens? 35mm cameras have a standard frame size of 24 x 36mm, so, if
>> you know the focal length of the lens, you will know the exact angle of
>> view. Since the size of the active portion of a digital camera sensor is
>> generally unknown, how can one determine the viewing angle?
>
> This is precisely why nearly all point-and-shoots are marked with
> "35mm-equivalent focal lengths". Despite many people railing against the
> practice. It's the only way in any kind of common use to specify what the
> range of views the camera will give you is.

This is probably the best I can hope for--and probably sufficient, if
reliable. I need a camera that will show as much as a 28mm lens would on a
35mm camera. I've noticed that digital cameras are a bit lacking in the
wide angle department. Telephoto with anti-shake is very nice, but not a
substitute for wide angle.

I have a 24mm lens for my Canon film camera. The difference between this
lens and the 28mm end of my 28-80mm zoom is dramatic--much more dramatic
than the measily 4mm discrepancy would suggest. I use the 24mm more than
either end of the zoom lens. 95% of my photos use either the 24mm or the
50mm f/1.4. And while we're on that subject, why do you suppose that the
extra 2 stops, relative to the f/2.8 zoom, come into play so often?

Norm
 >> Stay informed about: Focal length of digital camera lenses 

normanstrong RemoveThis @comcast.net wrote:
> "David Dyer-Bennet" wrote in message
>
> > normanstrong RemoveThis @comcast.net wrote:
> >> Is there some universal standard for specifying the focal length of a
> >> digital camera lens that will allow one to calculate the angle of view of
> >> that lens? 35mm cameras have a standard frame size of 24 x 36mm, so, if
> >> you know the focal length of the lens, you will know the exact angle of
> >> view. Since the size of the active portion of a digital camera sensor is
> >> generally unknown, how can one determine the viewing angle?
> >
> > This is precisely why nearly all point-and-shoots are marked with
> > "35mm-equivalent focal lengths". Despite many people railing against the
> > practice. It's the only way in any kind of common use to specify what the
> > range of views the camera will give you is.
>
> This is probably the best I can hope for--and probably sufficient, if
> reliable. I need a camera that will show as much as a 28mm lens would on a
> 35mm camera. I've noticed that digital cameras are a bit lacking in the
> wide angle department. Telephoto with anti-shake is very nice, but not a
> substitute for wide angle.
>
> I have a 24mm lens for my Canon film camera. The difference between this
> lens and the 28mm end of my 28-80mm zoom is dramatic--much more dramatic
> than the measily 4mm discrepancy would suggest. I use the 24mm more than
> either end of the zoom lens. 95% of my photos use either the 24mm or the
> 50mm f/1.4. And while we're on that subject, why do you suppose that the
> extra 2 stops, relative to the f/2.8 zoom, come into play so often?
>
> Norm

It depends on what you mean by digital camera. For example, I use a
10-20mm lens (which, on my camera, works like 15-30mm on 35mm film). I
think this is wide enough for most people (but am sure not for all!).
There are, in fact, several zooms starting around 10-12mm. The only
problem is that they are slow (around f/4).

If you don't want a DSLR, there are cameras with fixed zoom lenses and
reasonably wide lenses (but I don't think there's anything below 24mm
equivalent). You can find specifications for most cameras at
dpreview.com.
 >> Stay informed about: Focal length of digital camera lenses