Sunny 16 rule?

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?
--


John P Sheehy

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?
--


John P Sheehy

In message ZisYc.110794$Lj.34249@fed1read03,
"Mark M" wrote:

"Ken Scharf" wrote in message
...
Does the "sunny 16" exposure rule apply to
digicams?

Only as a rough guide.
You will discover that it is often too dark with either digital or slide
film.
You'll have to experiement with your camera.
As for my 10D, 16 is usually too dark.
F11 is closer--but then it varies a lot due to atmospheric conditions and
other factors.

The best-looking unaltered exposures of the embedded JPEGs (and
default-processed RAW files) of scenes taken under seeming "sunny f16"
conditions with my 10D work out to be "sunny f10", on the average.
--


John P Sheehy

In message ZisYc.110794$Lj.34249@fed1read03,
"Mark M" wrote:

"Ken Scharf" wrote in message
...
Does the "sunny 16" exposure rule apply to
digicams?

Only as a rough guide.
You will discover that it is often too dark with either digital or slide
film.
You'll have to experiement with your camera.
As for my 10D, 16 is usually too dark.
F11 is closer--but then it varies a lot due to atmospheric conditions and
other factors.

The best-looking unaltered exposures of the embedded JPEGs (and
default-processed RAW files) of scenes taken under seeming "sunny f16"
conditions with my 10D work out to be "sunny f10", on the average.
--


John P Sheehy

In message ,
(Fred McKenzie) wrote:

Others caught the apparent discrepancy in shutter speed. However, there is
another factor to consider. While the moon appears white to the eye, it is not
100 percent reflective. In other words, it is a big gray rock.

For the moon to look the way you expect (more white than gray), an additional
stop would be appropriate. Therefore your 1/200 second would be right on!

f8 @ 1/ISO is what works best for me, shooting a high full moon in clear
skies.

Of course, a low red moon on the horizon takes so long to expose at ISO
100 that it streaks.
--


John P Sheehy

In message ,
(Fred McKenzie) wrote:

Others caught the apparent discrepancy in shutter speed. However, there is
another factor to consider. While the moon appears white to the eye, it is not
100 percent reflective. In other words, it is a big gray rock.

For the moon to look the way you expect (more white than gray), an additional
stop would be appropriate. Therefore your 1/200 second would be right on!

f8 @ 1/ISO is what works best for me, shooting a high full moon in clear
skies.

Of course, a low red moon on the horizon takes so long to expose at ISO
100 that it streaks.
--


John P Sheehy

grim wrote:
"Peter Irwin" wrote
You do realise that 7% is just under one tenth of a stop?
...
A seven percent variation in light is really pretty tiny.

Yeah, which is why I said it's just one variable among other more important
ones to consider when using the "sunny 16" rule. Atmospheric haze, altitude,
dryness of the air, angle of the sun above the horizon, reflections, etc.,
etc., etc.

It is remarkable how often the rule is within a half stop of the
reading from an incident light meter. The angle of the sun
above the horizon makes less difference than you would think
except for the first two hours after sunrise and the last two
hours before sunset. Haze is something you have to judge and allow
for. Reflections are covered under the "light sand or snow" f/22
part of the rule, of course the same correction must be applied
to cloudy bright, so cloudy bright on light sand or snow should
be f/11.

7% here, 10% there, 20% elsewhere... it all makes for a "rule" that is a
pretty poor "rule". The sun isn't nearly as dependable as Roland implies.
I'd throw out the rule and use the camera's light meter.

Using a light meter is a really good idea, but I think if you
gave the rule a fair test you would be surprised how close
it will get you under bright sky conditions.

Peter.
--

grim wrote:
"Peter Irwin" wrote
You do realise that 7% is just under one tenth of a stop?
...
A seven percent variation in light is really pretty tiny.

Yeah, which is why I said it's just one variable among other more important
ones to consider when using the "sunny 16" rule. Atmospheric haze, altitude,
dryness of the air, angle of the sun above the horizon, reflections, etc.,
etc., etc.

It is remarkable how often the rule is within a half stop of the
reading from an incident light meter. The angle of the sun
above the horizon makes less difference than you would think
except for the first two hours after sunrise and the last two
hours before sunset. Haze is something you have to judge and allow
for. Reflections are covered under the "light sand or snow" f/22
part of the rule, of course the same correction must be applied
to cloudy bright, so cloudy bright on light sand or snow should
be f/11.

7% here, 10% there, 20% elsewhere... it all makes for a "rule" that is a
pretty poor "rule". The sun isn't nearly as dependable as Roland implies.
I'd throw out the rule and use the camera's light meter.

Using a light meter is a really good idea, but I think if you
gave the rule a fair test you would be surprised how close
it will get you under bright sky conditions.

Peter.
--

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.

At the appropriate bit levels, of course.

If you want to see something interesting take an image of a step gage,
download one of the freebie scientific image analysis software--ImageJ
is my favorite--and run a line profile on the image. Depending on what
the camera firmware is doing, the noise levels in the highlights can
be significantly different than the noise in the shadows. When anyone
(everyone?) says a camera has 'a' noise number, they are
simplifying--some times grossly--what is really going on.

jpc

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.

At the appropriate bit levels, of course.

If you want to see something interesting take an image of a step gage,
download one of the freebie scientific image analysis software--ImageJ
is my favorite--and run a line profile on the image. Depending on what
the camera firmware is doing, the noise levels in the highlights can
be significantly different than the noise in the shadows. When anyone
(everyone?) says a camera has 'a' noise number, they are
simplifying--some times grossly--what is really going on.

jpc