Sunny 16 rule?

jpc wrote:

the noise levels in the highlights can be significantly different
than the noise in the shadows.

Why wouldn't they? There is a read-out noise from the electronics,
and there is the photon shot noise from the act of exposing the sensor
to light. The former is constant, the latter's variance scales
linearly with exposu

noise = sqrt(read_out + exposure*signal)

is a reasonable approximation. Indeed, if you measure noise levels
vs. signal (linear), you can fit reasonably straight lines to the
square (variance) of the noise as a function of exposure.

jpc wrote:

the noise levels in the highlights can be significantly different
than the noise in the shadows.

Why wouldn't they? There is a read-out noise from the electronics,
and there is the photon shot noise from the act of exposing the sensor
to light. The former is constant, the latter's variance scales
linearly with exposu

noise = sqrt(read_out + exposure*signal)

is a reasonable approximation. Indeed, if you measure noise levels
vs. signal (linear), you can fit reasonably straight lines to the
square (variance) of the noise as a function of exposure.

"Roland Karlsson" wrote in message
...
"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 define sunny 16 to be correct, then it's correct. But the experience
here is that it underexposes by about a stop much of the time. And, of
course, if you are stuck only taking pictures in bright full sun, you aren't
going to have a lot of interesting pictures.

If you compare the
Sunny F16 to an incident meeter you will be surprised how
near it is on a clear day.

Dunno about where you live, but bright full sun in the parts of Japan I live
in is, well, bright. So the subjective appearance of subjects in bright full
sun is a lot brighter than they would be under subdued incandescent
lighting.

If you want an exposure that captures what the scene actually looked like,
incident metering is the wrong tool, and sunny 16 gives the wrong answer.

David J. Littleboy
Tokyo, Japan

"Roland Karlsson" wrote in message
...
"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 define sunny 16 to be correct, then it's correct. But the experience
here is that it underexposes by about a stop much of the time. And, of
course, if you are stuck only taking pictures in bright full sun, you aren't
going to have a lot of interesting pictures.

If you compare the
Sunny F16 to an incident meeter you will be surprised how
near it is on a clear day.

Dunno about where you live, but bright full sun in the parts of Japan I live
in is, well, bright. So the subjective appearance of subjects in bright full
sun is a lot brighter than they would be under subdued incandescent
lighting.

If you want an exposure that captures what the scene actually looked like,
incident metering is the wrong tool, and sunny 16 gives the wrong answer.

David J. Littleboy
Tokyo, Japan

"Roland Karlsson" wrote in message
...
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.

Slightly. Maybe. But incident metering gives you no artistsic control
whatsoever, since it doesn't relate what you see to what the film does. It's
really only useful for catalog photography.

To take control of your exposure, you need to learn how to use a spot meter.

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.

Incident metering is only useful when the whole scene is lit evenly. Since
this is extremely rare, it's pretty useless outside the studio.

David J. Littleboy
Tokyo, Japan

"Roland Karlsson" wrote in message
...
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.

Slightly. Maybe. But incident metering gives you no artistsic control
whatsoever, since it doesn't relate what you see to what the film does. It's
really only useful for catalog photography.

To take control of your exposure, you need to learn how to use a spot meter.

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.

Incident metering is only useful when the whole scene is lit evenly. Since
this is extremely rare, it's pretty useless outside the studio.

David J. Littleboy
Tokyo, Japan

On Mon, 30 Aug 2004 17:21:58 -0400, Alan Browne
wrote:

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.

Thanks for the link. Off and on I've been looking for a proceedure
like this one for the last couple years.

jpc

On Mon, 30 Aug 2004 17:21:58 -0400, Alan Browne
wrote:

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.

Thanks for the link. Off and on I've been looking for a proceedure
like this one for the last couple years.

jpc

Roland Karlsson wrote:
Ken Scharf wrote in news:lbpYc.40252$%
:


Does the "sunny 16" exposure rule apply to digicams?


Yes.


That's where on a bright sunny day
if you shot at f16 the exposure will be correct
if the shutter speed is equal to the ASA rating
of the film. So if you shot with ASA200 film,
you'd set the camera for 1/200 sec (closest match
would be 1/250 on most cameras).

Since many digicams don't stop down more than
F8, you'd double the shutter speed. IE:
set the camera at ASA200 and use 1/400 sec
(probably 1/500 is nearest setting).


Nope - F8 is two stops so you have to multiply with 4
or rather divide as 1/800 is a quarter of the time
of 1/200. But even better is to shot at ISO100, F5.6
and 1/800 or ISO50, F4 and 1/800. The compact digicams
(with small sensors) are not optimally sharp at F8.


Oh and here's a neat fact, the rule also applies
to taking photos of the full moon (since the moon
is in bright sunlight!). With a telescope having
an F8 objective lens shooting with ASA 100 film,
shutter speed of 1/200.

That's with film though, I assume digicams follow
the same rules.


Yepp.


/Roland
OOPS, ya I wrote that so quickly I forgot the
f stop sequence. Stop down from f16 one stop
to F11, THEN F8. But my idea did get through.

And also the sunny 16 rule would only apply to
those areas IN bright sun light. You'd need
more exposure for the shadows.

Which brings up another point, burning and
dodging. I used to do that with B&W film
under my enlarger, I guess photoshop and
the GIMP allow for this trick as well.

Roland Karlsson wrote:
Ken Scharf wrote in news:lbpYc.40252$%
:


Does the "sunny 16" exposure rule apply to digicams?


Yes.


That's where on a bright sunny day
if you shot at f16 the exposure will be correct
if the shutter speed is equal to the ASA rating
of the film. So if you shot with ASA200 film,
you'd set the camera for 1/200 sec (closest match
would be 1/250 on most cameras).

Since many digicams don't stop down more than
F8, you'd double the shutter speed. IE:
set the camera at ASA200 and use 1/400 sec
(probably 1/500 is nearest setting).


Nope - F8 is two stops so you have to multiply with 4
or rather divide as 1/800 is a quarter of the time
of 1/200. But even better is to shot at ISO100, F5.6
and 1/800 or ISO50, F4 and 1/800. The compact digicams
(with small sensors) are not optimally sharp at F8.


Oh and here's a neat fact, the rule also applies
to taking photos of the full moon (since the moon
is in bright sunlight!). With a telescope having
an F8 objective lens shooting with ASA 100 film,
shutter speed of 1/200.

That's with film though, I assume digicams follow
the same rules.


Yepp.


/Roland
OOPS, ya I wrote that so quickly I forgot the
f stop sequence. Stop down from f16 one stop
to F11, THEN F8. But my idea did get through.

And also the sunny 16 rule would only apply to
those areas IN bright sun light. You'd need
more exposure for the shadows.

Which brings up another point, burning and
dodging. I used to do that with B&W film
under my enlarger, I guess photoshop and
the GIMP allow for this trick as well.