Difficult technical question on ISO & light

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Let's see if I catch some guru's attention with this subject

I have recently bought a Canon S50 but probably any other camera would
not change the question. It would probably be the same even with a film
camera + lab processing.

I can't understand how the following thing works:

Case a.
I take a photo by night at ISO 50 without flash. In the photo I can see
the streetlights which have white color (RGB = 255,255,255), but all the
rest is very dark.

Case b.
I take the same photo (same time and lens aperture) at ISO 400 without
flash. This time I can see everything. The streetligts are always white
at RGB = 255,255,255 .

I cannot understand how the algorithm works, and not even the physics
behind all this: how can the ratio between the luminosity of the
streetlight and the luminosity of the walls of the houses CHANGE
depending on the ISO (50 vs 400)??



One could say that the reason for this is the clipping, that is, at 400
ISO the streetlights were more luminous than RGB = 255,255,255 but they
have been clipped to that value.

But I think this is NOT the reason because if it should be, then what
would be the explanation for the fact that EVERY picture I take in a
whatever dark environment ALWAYS contains at least 1 pixel at with one
of the three components (R,G or B) at 255? It seems like there is an
algorithm which multiplies the information from the CCD until at least 1
pixel of the image reaches the maximum value (255).

BUT THEN, if such a normalizing algorithm exists, again the photos in
case a. and b. should present the same luminosity ratio between the
streetlights and the walls of the houses, while it is not like this.

So what?

Thanks in advance.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

huerew wrote:

> Let's see if I catch some guru's attention with this subject
>
> I have recently bought a Canon S50 but probably any other camera would
> not change the question. It would probably be the same even with a film
> camera + lab processing.
>
> I can't understand how the following thing works:
>
> Case a.
> I take a photo by night at ISO 50 without flash. In the photo I can see
> the streetlights which have white color (RGB = 255,255,255), but all the
> rest is very dark.

All that is is that the light 'burned' through and was probably much higher that
what you measured in photoshop... 255 is at the limit of each color, so you got
clipped highlights. The rest of the frame was simply udnerexposed (0, or maybe
a bit more on 255).

>
> Case b.
> I take the same photo (same time and lens aperture) at ISO 400 without
> flash. This time I can see everything. The streetligts are always white
> at RGB = 255,255,255 .

Again, the streetlights are burned out and you're at the limit (in fact even
further, but it doesn't matter). But now, 3 stops more sensitivity so other
areas begin to fill in.

>
> I cannot understand how the algorithm works, and not even the physics
> behind all this: how can the ratio between the luminosity of the
> streetlight and the luminosity of the walls of the houses CHANGE
> depending on the ISO (50 vs 400)??

In an 8 bit per color case, a pixel can have a value of 0 (black) to 255 (full
saturation). When all three color elements are 0, (black); when all three color
elements are 255 it is pure white. When all 3 color elements are equal, but in
between, you get a shade of grey. When all 3 are 128, you get middle grey (18%
grey).

In you case however you had a scene with such low light that nothing registered
at ISO 50 except those parts of the scene that were very strong (too strong).
Near the lights you may have a halo area that quickly rolls from 255 down to
near 0 quickly.

At 400, you got more detail in the dark areas ... but the light was even further
beyond the sensitivity of the sensor and fully saturated.

>
> One could say that the reason for this is the clipping, that is, at 400
> ISO the streetlights were more luminous than RGB = 255,255,255 but they
> have been clipped to that value.

Yep.

>
> But I think this is NOT the reason because if it should be, then what
> would be the explanation for the fact that EVERY picture I take in a
> whatever dark environment ALWAYS contains at least 1 pixel at with one
> of the three components (R,G or B) at 255? It seems like there is an
> algorithm which multiplies the information from the CCD until at least 1
> pixel of the image reaches the maximum value (255).

A scene may easilly have more range than your film or CCD/CMOS can handle. Thie
means that either one end will be over exposed and other perhaps okay; or vice
versa ... and if the scene is really wide you will have both unexcited pixels
(too dark) and saturated (clipped) pixels. This is why one strategy is to place
the highlights at the extreme right of the histogram, and let the rest fall
where it may.

There is no compressing or decompressing. The sensor can hanlde so much scene
latitude and you the photographer has to place it correctly... in auto mode,
presumably the camera does this well... presumably.

Shoot RAW, put your hightlights at the extreme right of the histogram and you
will get the most detail that the camera can record in that scene.

Cheers,
Alan


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

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Whats wrong with you? You are making this too complicated. And did you
really need to cross post this to half a dozen newsgroups?

Digital film (senor) sensitivity are equivalent to film. The higher
the ISO the more sensitive the film is to light. So the higher the ISO
on a digital camera the more sentive to light the digital sensor is.
If one setting is higher than the other its going to be more sensative
to light and therfore capture more light in the scene.

Back to your question about the street lights. Obviously it will catch
whatever has the most light in a given scene, so the streetlights will
be brighter, even washed out without detail, because they are the
brightest part of the scene, while the rest of the scene is only
somewhat visable by comparision. Think about shooting the sun. Try
shooting a sunset. You will get an opposite effect in a bright scene.
The sun will be totally bright while while the rest of the landscape
will be pitch black because the sensor cannot hold to extremes of
light.

If you are in a dark scene use a tripod with lower ISO settings. If
you shoot handheld you will either get blur or a lot of grain, with
either digial or film. Also try to avoid extremes in lighting
especailly in dark scenes as you will get white washout from bright
sources of light like streetlights.

huerew <huerew@hhh.com> wrote in message news:<clrqmc01h3p@news3.newsguy.com>...
> Let's see if I catch some guru's attention with this subject
>
> I have recently bought a Canon S50 but probably any other camera would
> not change the question. It would probably be the same even with a film
> camera + lab processing.
>
> I can't understand how the following thing works:
>
> Case a.
> I take a photo by night at ISO 50 without flash. In the photo I can see
> the streetlights which have white color (RGB = 255,255,255), but all the
> rest is very dark.
>
> Case b.
> I take the same photo (same time and lens aperture) at ISO 400 without
> flash. This time I can see everything. The streetligts are always white
> at RGB = 255,255,255 .
>
> I cannot understand how the algorithm works, and not even the physics
> behind all this: how can the ratio between the luminosity of the
> streetlight and the luminosity of the walls of the houses CHANGE
> depending on the ISO (50 vs 400)??
>
>
>
> One could say that the reason for this is the clipping, that is, at 400
> ISO the streetlights were more luminous than RGB = 255,255,255 but they
> have been clipped to that value.
>
> But I think this is NOT the reason because if it should be, then what
> would be the explanation for the fact that EVERY picture I take in a
> whatever dark environment ALWAYS contains at least 1 pixel at with one
> of the three components (R,G or B) at 255? It seems like there is an
> algorithm which multiplies the information from the CCD until at least 1
> pixel of the image reaches the maximum value (255).
>
> BUT THEN, if such a normalizing algorithm exists, again the photos in
> case a. and b. should present the same luminosity ratio between the
> streetlights and the walls of the houses, while it is not like this.
>
> So what?
>
> Thanks in advance.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

255 is the maximum brightness value. By increasing the exposure you cannot
brighten the streetlights past 255. But you can brighten dim objects that
are well below 255.

Example:
Less exposure: Street surface 5, lights 255.
More exposure: Street surface 25, lights still 255 because it doesn't go any
higher.
If the camera had more dynamic range, the lights might have been 1000 and
5000 respectively. But the numbers don't go that high.

A more interesting question is why the exposure meter didn't give you
equivalent exposures, i.e., didn't compensate for the change in ISO setting,
and produce a similar looking picture each way.

The answer is probably that it bumped into a limit that doesn't depend on
ISO. The lens can only be opened so wide, and the shutter (I am guessing)
will only be allowed open for a certain maximum length of time (maybe 1/30
second), so that you actually got the same physical exposure at both ISO
settings.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

pk wrote:
>
> Whats wrong with you? You are making this too complicated. And did you
> really need to cross post this to half a dozen newsgroups?

I do agree this is should not have been crossposted.

> Digital film (senor) sensitivity are equivalent to film.

Incorrect. CCD or CMOS sensors are not equal to film; one is
not equivalent to then other. There are differenent physics
and imaging properties that apply to any giving situation.

Film has the ability to _accumulate_ light and endure long
exposures or multiple exposures that can capture detail
in the dimmest of situations. Reciprocity failure is the
only factor. Silicon simply can't do this and is limited by
both exposure latitude and length of exposure.

> The higher
> the ISO the more sensitive the film is to light. So the higher the ISO
> on a digital camera the more sentive to light the digital sensor is.

Digital sensors have a _nominal_ "speed" at which they
produce the best quality image. When you alter that speed
the image quality goes down. Film can be rated at a different
speeds and still produce quality results because as development
of film is altered, effective speed also alters. Also, a "slow"
film can be simply be exposed for a longer time than a faster
film, and achieve the same results. No loss in image quality.

Film can be exposed for hours. Try that with a digital sensor.
It simply one of the differences between these two imaging
mediums.


> If one setting is higher than the other its going to be more sensative
> to light and therfore capture more light in the scene.
>
> Back to your question about the street lights. Obviously it will catch
> whatever has the most light in a given scene, so the streetlights will
> be brighter, even washed out without detail, because they are the
> brightest part of the scene, while the rest of the scene is only
> somewhat visable by comparision. Think about shooting the sun. Try
> shooting a sunset. You will get an opposite effect in a bright scene.
> The sun will be totally bright while while the rest of the landscape
> will be pitch black because the sensor cannot hold to extremes of
> light.
>
> If you are in a dark scene use a tripod with lower ISO settings. If
> you shoot handheld you will either get blur or a lot of grain, with
> either digial or film. Also try to avoid extremes in lighting
> especailly in dark scenes as you will get white washout from bright
> sources of light like streetlights.
>
> huerew <huerew@hhh.com> wrote in message news:<clrqmc01h3p@news3.newsguy.com>...
> > Let's see if I catch some guru's attention with this subject
> >
> > I have recently bought a Canon S50 but probably any other camera would
> > not change the question. It would probably be the same even with a film
> > camera + lab processing.
> >
> > I can't understand how the following thing works:
> >
> > Case a.
> > I take a photo by night at ISO 50 without flash. In the photo I can see
> > the streetlights which have white color (RGB = 255,255,255), but all the
> > rest is very dark.
> >
> > Case b.
> > I take the same photo (same time and lens aperture) at ISO 400 without
> > flash. This time I can see everything. The streetligts are always white
> > at RGB = 255,255,255 .
> >
> > I cannot understand how the algorithm works, and not even the physics
> > behind all this: how can the ratio between the luminosity of the
> > streetlight and the luminosity of the walls of the houses CHANGE
> > depending on the ISO (50 vs 400)??
> >
> >
> >
> > One could say that the reason for this is the clipping, that is, at 400
> > ISO the streetlights were more luminous than RGB = 255,255,255 but they
> > have been clipped to that value.
> >
> > But I think this is NOT the reason because if it should be, then what
> > would be the explanation for the fact that EVERY picture I take in a
> > whatever dark environment ALWAYS contains at least 1 pixel at with one
> > of the three components (R,G or B) at 255? It seems like there is an
> > algorithm which multiplies the information from the CCD until at least 1
> > pixel of the image reaches the maximum value (255).
> >
> > BUT THEN, if such a normalizing algorithm exists, again the photos in
> > case a. and b. should present the same luminosity ratio between the
> > streetlights and the walls of the houses, while it is not like this.
> >
> > So what?
> >
> > Thanks in advance.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

>> One could say that the reason for this is the clipping, that is, at 400
>> ISO the streetlights were more luminous than RGB = 255,255,255 but they
>> have been clipped to that value.
>>
>> But I think this is NOT the reason because if it should be, then what
>> would be the explanation for the fact that EVERY picture I take in a
>> whatever dark environment ALWAYS contains at least 1 pixel at with one
>> of the three components (R,G or B) at 255? It seems like there is an
>> algorithm which multiplies the information from the CCD until at least 1
>> pixel of the image reaches the maximum value (255).
>>
>> BUT THEN, if such a normalizing algorithm exists, again the photos in
>> case a. and b. should present the same luminosity ratio between the
>> streetlights and the walls of the houses, while it is not like this.

There is no normalizing algorithm. Rather, almost every picture is going to
have a pixel that runs outside the available range of numbers and is clipped
at 255, simply because real-world subjects cover a tremendous brightness
range.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Tom Phillips wrote:

> That's the point. If the OP wants to obtain detail in nighttime
> exposures, he might try using a suitable film and employing
> a multiple exposure technique. No digital camera can do this.

Either that or he should stop crossposting...

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

"Justín Käse" wrote:
>
> In Message-ID:<4181C14A.D6ECD4FA@aol.com> posted on Thu, 28 Oct 2004
> 22:04:29 -0600, Tom Phillips wrote:
>
> >Film can be exposed for hours. Try that with a digital sensor.
> >It simply one of the differences between these two imaging
> >mediums.
>
> I used to have a rule of thumb with ASA100 film at f5.6, a scene lit by
> full moonlight took five minutes. This would bring out (saturate) all
> the colors, and providing there was no wind, give good resolution to
> leaves and foliage.
> I haven't tried it with the digicam yet, but thinking about what's been
> discussed, there wouldn't be any reciprocity failure to worry about as
> there would be no accumulative chemistry happening,

reciprocity failure isn't due to chemistry, but related
to quantum physics...


>neither would there
> be any increased darkness penetration effect either. Guess I won't be
> throwing away all my film cameras just yet. <g>

No you shouldn't In order for digital images to gather
more light, larger pixels are required. This increases
the Nyquist limitations and lessens resolution. Silver
haildes, OTOH, gain more resolution the _smaller_ the
grains are. This requires more exposure, bit only
reciprocity correction.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

"Justín Käse" wrote:
>
> In Message-ID:<41820CEB.85C0F622@aol.com> posted on Fri, 29 Oct 2004
> 03:27:15 -0600, Tom Phillips wrote:
>
> >
> >
> >"Justín Käse" wrote:
> >>
> >> In Message-ID:<4181C14A.D6ECD4FA@aol.com> posted on Thu, 28 Oct 2004
> >> 22:04:29 -0600, Tom Phillips wrote:
> >>
> >> >Film can be exposed for hours. Try that with a digital sensor.
> >> >It simply one of the differences between these two imaging
> >> >mediums.
> >>
> >> I used to have a rule of thumb with ASA100 film at f5.6, a scene lit by
> >> full moonlight took five minutes. This would bring out (saturate) all
> >> the colors, and providing there was no wind, give good resolution to
> >> leaves and foliage.
> >> I haven't tried it with the digicam yet, but thinking about what's been
> >> discussed, there wouldn't be any reciprocity failure to worry about as
> >> there would be no accumulative chemistry happening,
> >
> >reciprocity failure isn't due to chemistry, but related
> >to quantum physics...
>
> ...which is the basis of chemistry, no?

I suppose one could say it's photochemical. Technically
it's related to the intermittency effect, or the amount
of light available. Reciprocity failure at longer exposures
results from low irradiance of silver halides, meaning there
is too long a time -- too long a gap -- between the halide
molecules being struck with enough photons to initiate
nucleation and the formation of latent silver (photolysis;
typically three photons are required.) This is also why in
photography a 2+2 exposure does not equal a single exposure
of the same continuous length. But since silver halides can
accumulate exposure, _adding_ additional exposure (i.e.
a reciprocity correction) will compensate -- i.e., multiple
exposures are applicable.

Silicon sensors do not this, as they do not accumulate
multiple exposures and over exposure inherently begets
additional noise.

> Quantum theory is just the mind's imagination trying to comprehend
> phenomena that exceed our technical abilities of resolution.

You've lost me. Sorry.

> Counting subatomic particles smaller than the atomic probes we are
> currently limited to using, is like trying to read braille with your
> elbow.
> talk about nyquist limits. <g>

Well, nucleation occurs on a molecular level in silver
halide imaging. Silcon imaging requires a much greater
incidence of photons (photoelectrons) to generate a
signal for the same tonal "exposure."

> >>neither would there
> >> be any increased darkness penetration effect either. Guess I won't be
> >> throwing away all my film cameras just yet. <g>
> >
> >No you shouldn't In order for digital images to gather
> >more light, larger pixels are required.
>
> I thought pixel sensitivity was a function of semiconductor gain and was
> dependent on the difference between the idle state and the excited
> state, thus the astronomical use of refrigerants to chill CCDs as much
> as possible to enhance that difference.

Larger pixels help increase the gain also.

> I think it's only modern digicam sensors that use selective bias
> voltages to simulate ISO ratings for user convenience in varying
> situations, whereas astro-photographers strive for the utmost gain, and
> aren't concerned with desensitizing their equipment for "beach" pics.

I _think_ we agree.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

In article <4181C14A.D6ECD4FA@aol.com>,
Tom Phillips <nospam777@aol.com> wrote:
>
>Film can be exposed for hours. Try that with a digital sensor.
>It simply one of the differences between these two imaging
>mediums.

You really should avoid such pontifications unless you're absolutely certain
you're correct, as you aren't in this case. Canon's current DSLRs, to take
one example, manage perfectly hapilly with multi-hour exposures. The only
major problem is that holding the shutter open that long may drain the
battery.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Chris Brown wrote:
>
> In article <4181C14A.D6ECD4FA@aol.com>,
> Tom Phillips <nospam777@aol.com> wrote:
> >
> >Film can be exposed for hours. Try that with a digital sensor.
> >It simply one of the differences between these two imaging
> >mediums.
>
> You really should avoid such pontifications unless you're absolutely certain
> you're correct, as you aren't in this case. Canon's current DSLRs, to take
> one example, manage perfectly hapilly with multi-hour exposures. The only
> major problem is that holding the shutter open that long may drain the
> battery.


uh huh... multi-hour digital. And no noise due to heat. right.
(and heat is *inherent* in digital sensor exposure...)

Show me a "multi hour" digital exposure.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Tom Phillips wrote:
>
> Chris Brown wrote:
> >
> > In article <4181C14A.D6ECD4FA@aol.com>,
> > Tom Phillips <nospam777@aol.com> wrote:
> > >
> > >Film can be exposed for hours. Try that with a digital sensor.
> > >It simply one of the differences between these two imaging
> > >mediums.
> >
> > You really should avoid such pontifications unless you're absolutely certain
> > you're correct, as you aren't in this case. Canon's current DSLRs, to take
> > one example, manage perfectly hapilly with multi-hour exposures. The only
> > major problem is that holding the shutter open that long may drain the
> > battery.
>
> uh huh... multi-hour digital. And no noise due to heat. right.
> (and heat is *inherent* in digital sensor exposure...)
>
> Show me a "multi hour" digital exposure.

And I don't mean astrophotography.

The ability of the canon EOS to do astrophotography is
in part due to the employment of a larger pixel. Larger
pixels mean a better signal and less noise, *but* (also
less pixel resolution. So _pictorial_ resolution is
sacrificed for better signal and less noise. This is hardly
comparable with film, where resolution abilities is not
based on large grain size, but _small_ grain size and where
exposure and signal frequency is on a molecular level, not
a pixel level.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

"pk" <pkim0908@gmail.com> wrote in message
news:af6200a1.0410281933.7416b5ea@posting.google.com...
> Whats wrong with you? You are making this too complicated. And did you
> really need to cross post this to half a dozen newsgroups?
> [...]
> huerew <huerew@hhh.com> wrote in message
> news:<clrqmc01h3p@news3.newsguy.com>...
>> Let's see if I catch some guru's attention with this subject

Overanalysis Paralasis.

It seems that below the confusion regarding exposure is a misunderstanding
regarding the eye and film. The eye (and brain) process an image so that you
see a great range of brightness. Film is not that way. Look to the film
sensitivity chart where film's sensitivity to gradations of light is plotted
in a log curve. Better now? So simple when you get that.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

In article <4181DC73.F1671D33@aol.com>,
Tom Phillips <nospam777@aol.com> wrote:

>Talking lighting and exposure here. And again you ignore
>nyquist. Also, on average a 400 speed 35mm film has the
>equivalent of 24 million pixels.

Oh wow, a real 35mm pixel-counter. I thought the last one of those in the
wild had died out years ago...

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Chris Brown wrote:
>
> In article <4181DC73.F1671D33@aol.com>,
> Tom Phillips <nospam777@aol.com> wrote:
>
> >Talking lighting and exposure here. And again you ignore
> >nyquist. Also, on average a 400 speed 35mm film has the
> >equivalent of 24 million pixels.
>
> Oh wow, a real 35mm pixel-counter. I thought the last one of those in the
> wild had died out years ago...


No, stupid. It's something that's been scientifically determined
by eminent photo scientists based on the number of absorbed photons.
Not that the two are equal...

 

[john]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

On Fri, 29 Oct 2004 00:08:21 +0200, huerew <huerew@hhh.com> wrote:

>Xref: sn-us alt.comp.periphs.dcameras:58712 rec.photo.digital:1048214 rec.photo.equipment.35mm:865238 rec.photo.film+labs:76078 rec.photo.darkroom:208187
>
>Let's see if I catch some guru's attention with this su

Please post to the appropriate group and only to the
appropriate group.


Regards,

John S. Douglas, Photographer - http://www.puresilver.org
Vote "No! for the status quo. Vote 3rd party !!

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

In article <4182032A.D3B720F7@aol.com>,
Tom Phillips <nospam777@aol.com> wrote:

>uh huh... multi-hour digital. And no noise due to heat. right.
>(and heat is *inherent* in digital sensor exposure...)
>
>Show me a "multi hour" digital exposure.

OK, I'll take one tonight and upload it. Have to be of something indoors and
boring, I'm afraid, as there's too much light pollution where I live to do
such a long exposure outside, and the weather's pretty nasty atm as well.

Watch this space.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

"Tom Phillips" <nospam777@aol.com> wrote in message
news:41823255.BC08FE81@aol.com...
>
> Photography produces a photograph. And a photograph is an
> image written on photosensitive materials by the direct
> action of light. Digital imaging is electronic and about
> as "photographic" as your television cameraman broadcasting
> to your T.V. set. Again, no photograph.

Photograph, from the greek "photo-" meaning light and "-graph" meaning
recording. Whether the recording was made photochemically and stored on
physical media or photoelectrically and stored on digital media is really
inconsequential to its status as a photograph.

Ken

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Ken Alverson wrote:
>
> "Tom Phillips" <nospam777@aol.com> wrote in message
> news:41823255.BC08FE81@aol.com...
> >
> > Photography produces a photograph. And a photograph is an
> > image written on photosensitive materials by the direct
> > action of light. Digital imaging is electronic and about
> > as "photographic" as your television cameraman broadcasting
> > to your T.V. set. Again, no photograph.
>
> Photograph, from the greek "photo-" meaning light and "-graph" meaning
> recording. Whether the recording was made photochemically and stored on
> physical media or photoelectrically and stored on digital media is really
> inconsequential to its status as a photograph.
>
> Ken


No. it means (literally) light writing, i.e., as in physically
drawing with light.

Digital sensors produce data.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

In article <41823255.BC08FE81@aol.com>,
Tom Phillips <nospam777@aol.com> wrote:
>
>>
>> The medium format does give me superior image quality to both of them, and
>> it's dramatically superior. The relative difference between the digital and
>> 35mm, in comparison, is not worth bothering with. They're both adequate for
>> an A4 print, and ropey for an A3 print.
>
>Never shot Kodachrome 25 or 64, I gather...

Usually Velvia 50, although I'm doing a lot more Provia 100F these days.

>The questionn is, why is this even a debate?

It's not - in the eyes of nearly everyone who regarded this as some kind of
"contest", 35mm "lost" years ago, with the previous genertion of DSLRs.
You're trotting out the sort of stuff that used to infest r.p.e.35mm and
r.p.d about 2-4 years ago. Pretty much everyone else has accepted reality
and moved on.

>For _pictorial_ imaging, film is the better medium. The
>facts bear this out.

I quite agree, you just need the film to be 6cm wide or more to compete
in the quality stakes these days.

>Digital,imaging is not photographic. It does not produce
>a photograph.

If you say so.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

Chris Brown wrote:
>
> In article <41823255.BC08FE81@aol.com>,
> Tom Phillips <nospam777@aol.com> wrote:
> >
> >>
> >> The medium format does give me superior image quality to both of them, and
> >> it's dramatically superior. The relative difference between the digital and
> >> 35mm, in comparison, is not worth bothering with. They're both adequate for
> >> an A4 print, and ropey for an A3 print.
> >
> >Never shot Kodachrome 25 or 64, I gather...
>
> Usually Velvia 50, although I'm doing a lot more Provia 100F these days.
>
> >The questionn is, why is this even a debate?
>
> It's not - in the eyes of nearly everyone who regarded this as some kind of
> "contest", 35mm "lost" years ago, with the previous genertion of DSLRs.
> You're trotting out the sort of stuff that used to infest r.p.e.35mm and
> r.p.d about 2-4 years ago. Pretty much everyone else has accepted reality
> and moved on.

Pixels are still limited by Nyquist. The garden variety
consumer digital camera uses a bayer pattern, meaning color
pixels are interpolated 4:1 to get one full color pixel.
Thus the sensor reolution does not reflect the actual image
pixel resolution. There's a long way to go before one
shot consumer digital cameras can match even 35mm film.
Now, it may look good in typical consumer prints, but to
the human eye this only requires about 6mp to achieve.
What I'm saying is the average 400 speed color film has
more resolving ability than this available, even if it's
not typically needed or used by the average consumer.

> >For _pictorial_ imaging, film is the better medium. The
> >facts bear this out.
>
> I quite agree, you just need the film to be 6cm wide or more to compete
> in the quality stakes these days.

Well, I shoot 4x5. Pixels will never be able to get that
small or numerous to effectively compete there.

> >Digital,imaging is not photographic. It does not produce
> >a photograph.
>
> If you say so.

It's not what anyone says, it's what the technology actually
does and doesn't do. It produces data, which is why it's a
_different_ imaging medium. Data is not an optical image nor
a phototgraph. Thus while an imaging medium, it's not
photographic.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

On Fri, 29 Oct 2004 06:06:53 -0600, Tom Phillips <nospam777@aol.com>
wrote:

>
>
>Chris Brown wrote:
>>
>> In article <418210F6.561BFC92@aol.com>,
>> Tom Phillips <nospam777@aol.com> wrote:
>> >
>> >
>> >Chris Brown wrote:
>> >>
>> >> In article <4181DC73.F1671D33@aol.com>,
>> >> Tom Phillips <nospam777@aol.com> wrote:
>> >>
>> >> >Talking lighting and exposure here. And again you ignore
>> >> >nyquist. Also, on average a 400 speed 35mm film has the
>> >> >equivalent of 24 million pixels.
>> >>
>> >> Oh wow, a real 35mm pixel-counter. I thought the last one of those in the
>> >> wild had died out years ago...
>> >
>> >
>> >No, stupid.
>>
>> I bet that's what you say to all the girls.
>>
>> >It's something that's been scientifically determined
>> >by eminent photo scientists based on the number of absorbed photons.
>>
>> Your alluded to "scientific determination" doesn't match the reality
>> observed by those of us who shoot multiple systems. In said observed
>> reality, 35mm film can just about edge out 6 megapixel DSLRs at low ISO,
>
>***ONLY*** at typical machine print sizes. In fact, any 35mm
>image can be *enlarged* to as much as 10 times it's resolution,
>revealing additional image detail. No digital image of a similar
>pixel resolution can achieve this capability. A higher resolution
>capture is required.
>
>This is simply due to the fact that silver halides record
>tonal/image information on a molecular level as opposed to
>a much larger pixel. This is an inherent distinction between
>these two imaging mediums.

off track .. this only happens if the emulsion would consist of free
molecules in a monomolecular layer at 100% molecular density .. it is
not, even if microcrystaline it still is crystaline .. and hence you
do not get a 100 chemical reaction to light ..

 

[jeremy]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

"imbsysop" <imbsysop@yahoo.com> wrote in message
news:dhj4o0170118qehg72lt3e1fj6hf438g0m@4ax.com...
> >> >> >Talking lighting and exposure here. And again you ignore
> >> >> >nyquist. Also, on average a 400 speed 35mm film has the
> >> >> >equivalent of 24 million pixels.
> >> >>
> >> >> Oh wow, a real 35mm pixel-counter. I thought the last one of those
in the
> >> >> wild had died out years ago...

Kodak quotes 24 MP as the equivalent of 35mm film, on their website.
Whether you can observe the difference in image quality is another issue.

I would accept Kodak's assessment, because I consider them qualified to make
it.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

imbsysop wrote:
>
> On Fri, 29 Oct 2004 06:06:53 -0600, Tom Phillips <nospam777@aol.com>
> wrote:
>
> >
> >
> >Chris Brown wrote:
> >>
> >> In article <418210F6.561BFC92@aol.com>,
> >> Tom Phillips <nospam777@aol.com> wrote:
> >> >
> >> >
> >> >Chris Brown wrote:
> >> >>
> >> >> In article <4181DC73.F1671D33@aol.com>,
> >> >> Tom Phillips <nospam777@aol.com> wrote:
> >> >>
> >> >> >Talking lighting and exposure here. And again you ignore
> >> >> >nyquist. Also, on average a 400 speed 35mm film has the
> >> >> >equivalent of 24 million pixels.
> >> >>
> >> >> Oh wow, a real 35mm pixel-counter. I thought the last one of those in the
> >> >> wild had died out years ago...
> >> >
> >> >
> >> >No, stupid.
> >>
> >> I bet that's what you say to all the girls.
> >>
> >> >It's something that's been scientifically determined
> >> >by eminent photo scientists based on the number of absorbed photons.
> >>
> >> Your alluded to "scientific determination" doesn't match the reality
> >> observed by those of us who shoot multiple systems. In said observed
> >> reality, 35mm film can just about edge out 6 megapixel DSLRs at low ISO,
> >
> >***ONLY*** at typical machine print sizes. In fact, any 35mm
> >image can be *enlarged* to as much as 10 times it's resolution,
> >revealing additional image detail. No digital image of a similar
> >pixel resolution can achieve this capability. A higher resolution
> >capture is required.
> >
> >This is simply due to the fact that silver halides record
> >tonal/image information on a molecular level as opposed to
> >a much larger pixel. This is an inherent distinction between
> >these two imaging mediums.
>
> off track .. this only happens if the emulsion would consist of free
> molecules in a monomolecular layer at 100% molecular density .. it is
> not, even if microcrystaline it still is crystaline .. and hence you
> do not get a 100 chemical reaction to light ..

Silver hailde exposure occurs at the molecular level.

 

[Guest]

Archived from groups: alt.comp.periphs.dcameras,rec.photo.digital,rec.photo.equipment.35mm,rec.photo.film+labs,rec.photo.darkroom (More info?)

In article <26k952-5k8.ln1@narcissus.dyndns.org>,
Chris Brown <cpbrown@ntlworld.no_uce_please.com> wrote:
>In article <4182032A.D3B720F7@aol.com>,
>Tom Phillips <nospam777@aol.com> wrote:
>
>>uh huh... multi-hour digital. And no noise due to heat. right.
>>(and heat is *inherent* in digital sensor exposure...)
>>
>>Show me a "multi hour" digital exposure.
>
>OK, I'll take one tonight and upload it. Have to be of something indoors and
>boring, I'm afraid, as there's too much light pollution where I live to do
>such a long exposure outside, and the weather's pretty nasty atm as well.

In the meantime, here's a 30 minute one to be going on with. I downsized it
for the web, but included a 1:1 crop in part of the pic, so that you can see
just how "terrible" the noise is.

Ambient temperature was about 15C.

http://homepage.ntlworld.com/narcissus/30mins.jpg