Sunny 16 rule?

"David J. Littleboy" wrote in
:

If you care about your exposures, you'll find that Sunny 16 is rarely
correct.

It's not just shadows: sunny 16 simply is simply wrong too much of the
time to use for slides and digital.

Depends on what you define by correct. If you compare the
Sunny F16 to an incident meeter you will be surprised how
near it is on a clear day. An incident light meeter assumes
that the subject contains some almost white parts.

If you use a spot meter and take a photo of a dark tree trunk,
then it contains no white parts and it can be exposed much
more than the Sunny F16 rule.


/Roland

"David J. Littleboy" wrote in
:

If you care about your exposures, you'll find that Sunny 16 is rarely
correct.

It's not just shadows: sunny 16 simply is simply wrong too much of the
time to use for slides and digital.

Depends on what you define by correct. If you compare the
Sunny F16 to an incident meeter you will be surprised how
near it is on a clear day. An incident light meeter assumes
that the subject contains some almost white parts.

If you use a spot meter and take a photo of a dark tree trunk,
then it contains no white parts and it can be exposed much
more than the Sunny F16 rule.


/Roland

Alan Browne wrote in news:WfsYc.15432
:

In any case, if R,G,B are each in the range 110 - 130 for a
properly exposed shot of a grey card, then it is likely the
metering of the camera is correct.


Yepp - but that does not tell you that the ISO
number is correct. Maybe it is ISO 50 instead
of (claimed) ISO 100 and the time is actually
1/50 and not the (claimed) 1/100. That would
give the same exposure.


/Roland

Alan Browne wrote in news:WfsYc.15432
:

In any case, if R,G,B are each in the range 110 - 130 for a
properly exposed shot of a grey card, then it is likely the
metering of the camera is correct.


Yepp - but that does not tell you that the ISO
number is correct. Maybe it is ISO 50 instead
of (claimed) ISO 100 and the time is actually
1/50 and not the (claimed) 1/100. That would
give the same exposure.


/Roland

jpc wrote in :

The definition of ISO film sensitivity is rooted in physics:

[15.4  f.no^2 / (cd/m2  t) ] = ISO numbers for 18% grey exposure.

My reference book (Photographic Materials and Processes, Focal Press
1986 pp 54-56) defines a film ISO number as 1/H x .8 where H
(exposure) is measured in Lux sec. At this exposure the film has an
optical density of .1 over the fog. The .8 is safety factor.


You are right. The above definition is weird.


/Roland

jpc wrote in :

The definition of ISO film sensitivity is rooted in physics:

[15.4  f.no^2 / (cd/m2  t) ] = ISO numbers for 18% grey exposure.

My reference book (Photographic Materials and Processes, Focal Press
1986 pp 54-56) defines a film ISO number as 1/H x .8 where H
(exposure) is measured in Lux sec. At this exposure the film has an
optical density of .1 over the fog. The .8 is safety factor.


You are right. The above definition is weird.


/Roland

John McWilliams wrote in news:bBHYc.86598$Fg5.55978
@attbi_s53:

Interesting thread, but under what circumstances - today - would one
want or need the sunny 16? Back when meters were atrocious or it was
hugely expensive to buy a good one, understood. Back when one might
have
forgotten one's light meter and wanted an approximation, understood.

It is useful - to understand the nature of exposure.

Today's cameras have several flashy named methods for determining
the exposure. Methods that use several meassuring points and
trying to find the correct value - the exposure value.

But - if you use an incident light meeter and assumes that
your subject has reasonable reflectance, you get that number
without any advanced electronics at all. An lo - if you do
that in bright sunshine - you get almost similar values
every time, the Sunny F16 (or Sunny F10 for D10 .

This gives you a deeper understanding. The world consists
of reflecting objects, from black to white. Nothing is
really blacker than say 1% and nothing is whiter than 100%.
So - you can use exactly the same exposure for all subjects,
totally independent of the subjects actual reflectance.

The problem arises when you have shadows and reflecting
objects of course.


/Roland

John McWilliams wrote in news:bBHYc.86598$Fg5.55978
@attbi_s53:

Interesting thread, but under what circumstances - today - would one
want or need the sunny 16? Back when meters were atrocious or it was
hugely expensive to buy a good one, understood. Back when one might
have
forgotten one's light meter and wanted an approximation, understood.

It is useful - to understand the nature of exposure.

Today's cameras have several flashy named methods for determining
the exposure. Methods that use several meassuring points and
trying to find the correct value - the exposure value.

But - if you use an incident light meeter and assumes that
your subject has reasonable reflectance, you get that number
without any advanced electronics at all. An lo - if you do
that in bright sunshine - you get almost similar values
every time, the Sunny F16 (or Sunny F10 for D10 .

This gives you a deeper understanding. The world consists
of reflecting objects, from black to white. Nothing is
really blacker than say 1% and nothing is whiter than 100%.
So - you can use exactly the same exposure for all subjects,
totally independent of the subjects actual reflectance.

The problem arises when you have shadows and reflecting
objects of course.


/Roland

jpc wrote:
On Mon, 30 Aug 2004 10:44:53 -0400, Alan Browne
wrote:


jpc wrote:


On Mon, 30 Aug 2004 00:07:02 GMT, wrote:



In message ,
Alan Browne wrote:


From time to time you will see postings that suggest the

manufacturers do not follow the ISO sensitivity very well.

Which could mean that claims of noise at specific ISOs are meaningless.

If camera A has the same noise at ISO 200 that camera B has at ISO 100,
who's to say that they both not really ISO 140, and have the same noise?



In the film world, an ISO number is fundamental property of the
emulsion. In the digital world an ISO number is simply a misnamed gain
setting. Unless the camera firmware is heavily filtering the image at
high A/D gain settings--aka iso numbers--the sensor noise at gain 1 is
only multipied by successive factors of two.

The definition of ISO film sensitivity is rooted in physics:

[15.4 • f.no^2 / (cd/m2 • t) ] = ISO numbers for 18% grey exposure.


My reference book (Photographic Materials and Processes, Focal Press
1986 pp 54-56) defines a film ISO number as 1/H x .8 where H
(exposure) is measured in Lux sec. At this exposure the film has an
optical density of .1 over the fog. The .8 is safety factor.

We agree on the exposure, but I don't follow how the f# enters into
the equation. Could you explain further or supply a reference

http://www.kodak.com/global/plugins/...asurements.pdf

in the equation presented (p.2), L (luminance) is in Cd/m^2 .

If you're measuring from a target (18% grey), then of course for
the time and the amount of light, the aperture needs to be
considered as well.

Cheers,
Alan


--
-- rec.photo.equipment.35mm user resource:
-- http://www.aliasimages.com/rpe35mmur.htm
-- e-meil: there's no such thing as a FreeLunch.--

jpc wrote:
On Mon, 30 Aug 2004 10:44:53 -0400, Alan Browne
wrote:


jpc wrote:


On Mon, 30 Aug 2004 00:07:02 GMT, wrote:



In message ,
Alan Browne wrote:


From time to time you will see postings that suggest the

manufacturers do not follow the ISO sensitivity very well.

Which could mean that claims of noise at specific ISOs are meaningless.

If camera A has the same noise at ISO 200 that camera B has at ISO 100,
who's to say that they both not really ISO 140, and have the same noise?



In the film world, an ISO number is fundamental property of the
emulsion. In the digital world an ISO number is simply a misnamed gain
setting. Unless the camera firmware is heavily filtering the image at
high A/D gain settings--aka iso numbers--the sensor noise at gain 1 is
only multipied by successive factors of two.

The definition of ISO film sensitivity is rooted in physics:

[15.4 • f.no^2 / (cd/m2 • t) ] = ISO numbers for 18% grey exposure.


My reference book (Photographic Materials and Processes, Focal Press
1986 pp 54-56) defines a film ISO number as 1/H x .8 where H
(exposure) is measured in Lux sec. At this exposure the film has an
optical density of .1 over the fog. The .8 is safety factor.

We agree on the exposure, but I don't follow how the f# enters into
the equation. Could you explain further or supply a reference

http://www.kodak.com/global/plugins/...asurements.pdf

in the equation presented (p.2), L (luminance) is in Cd/m^2 .

If you're measuring from a target (18% grey), then of course for
the time and the amount of light, the aperture needs to be
considered as well.

Cheers,
Alan


--
-- rec.photo.equipment.35mm user resource:
-- http://www.aliasimages.com/rpe35mmur.htm
-- e-meil: there's no such thing as a FreeLunch.--