ortho, not pan film

[Q.G.]

Green has some yellow in it.

Not so. Green is green, yellow is yellow.
A film that is green sensitive needs another 100 nm or so worth of extended sensitivity to also capture yellow.

 

[Photo Engineer]

The ADOX orthopan-films were called "revolutionizing" when they came out in the late 40's because of their sharpness and extremely fine grain. Dr. Schleussner Fotowerke (later called ADOX) was founded in 1860, so they should have had the knowledge about sensitizing film?

Old german photography books tells about orthochromatic, panchromatic, orthopanchromatic and superpanchromatic emulsions.

You must remember that sharpness and grain have nothing to do with spectral sensitivity. You also have to remember that the German chemists came up with very "non technical" descriptions for their sensitization which we in the US called by name as short and long red for example, replacing the qualitative names assigned by the Germans. This was probably advertizing, as usually, the US companies didn't mention sensitization except in technical articles.

As for B&W papers, today even the simpler graded contrast papers are ortho sensitive. They are probably made so to match the speed and sensitivity of VC papers to white light (grade 2 normally).

PE

 

[Ray Rogers]

i didn't realize there were differences, i had thought that photo paper,
was "orthochromatic" generally speaking because it was not panchromatic.

hmmm, i guess i was calling blue sensitive "ortho" without realizing there was a difference ....
so does this mean that photo paper is "ortho" and sensitive to green
as well as blue, or is it only blue sensitive or something different altogether ?

early photographic processes that just use silver nitrate ( like wet plate, dry plate ( some ) &C
would they be considered something else besides "orthochromatic"

thanks in advance !

- john

Exactly.

The "native" form starts out without any spectral sensitization.
Those are "unsensitized" or "blue sensitive" and may be sensitive mostly to
UV and some blue. (Ordinary B/W photographic papers, salt prints and siderotype processes belong here.)


If you sensitize for green the material becomes "orthrochromatic".
(MC/VC photographic papers fall into this category.)

If in addition you also sensitize for red,
the material can be called "panchromatic"
(There used to be a few panchromatic b/w papers
for printing b/w prints from color negs.
Total darkness was the best safelight.)

 

[removed account4]

it never ceases to amaze me how complicated
the simple ( looking at least ) things we take for granted are.

thanks for the help on this, i have a little more of a clue now
but that said, i will be the first to admit, i am still pretty clueless

 

[CBG]

... Green has some yellow in it.

True if one is adding paint colors but, but here we are talking about adding light and that is rather different. The primaries that matter for film are red, blue, and green. So, with the light impinging upon film, the green light is not the product of adding two other colors.

For light
Primaries are red, blue, and green
Adding primaries gets you the secondaries, cyan, magenta and yellow.
Red and blue = magenta,
red and green = yellow,
green and blue = cyan.
Red and blue and green (in the right proportions) = white

In a darkened room if you put the bright spot a strongly gelled red spotlight on a white wall, and then direct the spot from a strongly gelled green spot on top of it, the light you get is yellow. Not intuitive at all.

But...

For paint - things are more inutitive:
Primaries are red, yellow, and blue.
Adding primaries gets you the secondaries.
Red and blue = purple,
red and yellow = orange,
blue and yellow = green.
Red and blue and green (in the right proportions) = black

Weird, huh?

So, flipping your sentence around - yellow has some green in it.

So... For film and filters (and I am talking about strong filters):
Primaries - the blue filters pass only blue,
red filters pass only red,
green filters pass only green.
Secondaries - magenta filters pass red and blue,
yellow filters pass green and red,
cyan filters pass green and blue.

Among other consequences, all that means that to mimic a plain emulsion with a pan film and filters, use a blue filter. To mimic an ortho emulsion, use a cyan filter which passes blue and green.

 

[Ray Rogers]

Old german photography books tells about orthochromatic, panchromatic, orthopanchromatic and superpanchromatic emulsions.

Yea.

They discovered it and did a lot of the early work.
Early names later needed to be amened/extended....

 

[RobertV]

How much red light

Yes, you can develop by dark red light (used for X-ray development) this TONAL Orthopan film.

 

[RobertV]

Rollei Retro 100 TONAL (E.I.80) in AM74/RHS 1+9.

 

[hrst]

CBG;

When talking about spectral sensitivity, we should forget the concepts of "primary" and "secondary" colors or color mixing. They are relevant when talking about human vision or color products, but when talking about pure sensitivity, the only thing that matters is wavelength - how the emulsion responses to different wavelengths.

To make this clear, I say "yellow wavelength" instead of just "yellow".

"Yellow" can be many different things; it can be a mixture of two distinct spikes of red and green wavelengths, or it can be a broad, continuous range of wavelengths from green to red, or it can be a single spike between the red and green wavelengths - this is "yellow wavelength". The point is, the last case (monochromatic yellow) does not record on BW film that is sensitized from blue to green, but the two former record on the very same film; and still, we see all of these yellows EXACTLY the same with our eyes. Color films, or digital cameras, would also render them same, as they are designed to somewhat match human vision by having overlapping spectral responses in emulsions. But, once we are talking about BW emulsion's spectral characteristics, we can forget all that. It's just the wavelength content that counts.

 

[JPD]

So green doesn't always contain yellow. A book could be written with all the knowledge from this forum.

You also have to remember that the German chemists came up with very "non technical" descriptions for their sensitization which we in the US called by name as short and long red for example, replacing the qualitative names assigned by the Germans. This was probably advertizing, as usually, the US companies didn't mention sensitization except in technical articles.

Advertizing perhaps, or words invented by writers to simplify things. After all, "ortho-" and "panchromatic" are also words that were invented to fit the sensitizations. Trivial names are often convenient. "Metol" isn't a very good technical description, but is easier to use than... Darn, I can't remember.

The word "Pan-" was registered to AGFA until 1937.

Another name for "super-panchromatic" is "ultra-panchromatic":

http://oi52.tinypic.com/z3m9i.jpg

(Das Rolleiflex Buch, 1938)

 

[Roger Cole]

If in addition you also sensitize for red,
the material can be called "panchromatic"
(There used to be a few panchromatic b/w papers
for printing b/w prints from color negs.
Total darkness was the best safelight.)

And while the earlier Panalure wasn't very good, by the time I used the later Panalure RC in the late 90s it was quite handy. I wish someone would make such a paper (maybe in FB in a couple of grades) again. I used my Duka 50 sodium safelight set the same as I used for RA4. It was far from bright but did make handling it a lot easier than no safelight, and tested safe for normal times.

Anyone else miss Panalure? Any chance of pursuading one of the European paper makers to make something like it again?

/digression.

 

[Photo Engineer]

To me, Panalure looked a bit like Kodabromide with the curve shape tweaked a tad. It would be possible to make one today provided one could get the right sensitizing dye.

PE

 

[Q.G.]

So green doesn't always contain yellow.

Green never contains yellow.

The impression of green you get when mixing blue and yellow paints is because green light is not absorbed by those paints.
It's green, because it does not contain yellow (and blue, etc.) anymore.

 

[JPD]

Green never contains yellow.

The impression of green you get when mixing blue and yellow paints is because green light is not absorbed by those paints.
It's green, because it does not contain yellow (and blue, etc.) anymore.

So one can say that a yellow-green shade is just that, and is not a mix of anything?

 

[Q.G.]

So one can say that a yellow-green shade is just that, and is not a mix of anything?

Indeed.
There is a band of wavelengths we call "green". And there is a (more narrow) band of wavelengths we call "yellow". (And other parts of the spectrum we need not concern ourselves with now).
And there is a transition area which we would call neither "green" nor "yellow". Or both, depending on our mood and what we ate yesterday.
That area is not a mix of "green" and "yellow". Just different wavelengths, different colours we do not have a proper name for.

 

[DWThomas]

Green never contains yellow.

The impression of green you get when mixing blue and yellow paints is because green light is not absorbed by those paints.
It's green, because it does not contain yellow (and blue, etc.) anymore.

Yes, there is a whole book out on watercolor and mixing of colors that's titled Blue and Yellow Don't Make Green where the author (a guy named Wilcox IIRC) explains that phenomenon.

 

[JPD]

Indeed.
There is a band of wavelengths we call "green". And there is a (more narrow) band of wavelengths we call "yellow". (And other parts of the spectrum we need not concern ourselves with now).
And there is a transition area which we would call neither "green" nor "yellow". Or both, depending on our mood and what we ate yesterday.
That area is not a mix of "green" and "yellow". Just different wavelengths, different colours we do not have a proper name for.

That makes sense. I'm going to use this knowledge on my friends, attack them like a Besserwisser Bf 109.

 

[hrst]

So one can say that a yellow-green shade is just that, and is not a mix of anything?

Yellow-green shade can be a single, monochromatic spectral spike between green and yellow wavelengths (what you describe), or it can be a mix of pure green and pure yellow wavelenghts, or it can be a mix of pure green and pure red wavelengths, the red one being much lower in level, or pure green and orange, or it can be a continuous region from green to yellow, or from green to red, lowering in level towards red, etc. etc. etc. If you give up a little in saturation (which is hard to evaluate, after all), you may even have a mixture of bluish-green and pure red, and that mixture still looks like yellow-green!

So again, there are countless possibilities and our eyes cannot make difference. Some of them may be rendered differently by different color films or different digital cameras, but mostly they try to mimic the eye vision as much as possible.

Our eyes only detect three broad overlapping wavelength regions. So, monochromatic, pure yellow gives equal signal to both "red" and "green" detectors because the spectral sensitivities of "red" and "green" detectors in our eyes overlap. If they didn't overlap, we would see monochromatic "in-between" colors black which wouldn't be very nice. And, for example, a signal of 80% "green" 20% "red" would translate as "yellow-green shade" in our brain.

The only thing we can judge by our eyes to some extent, is that when we see VERY pure and saturated RED, GREEN or BLUE, then we can know they are relatively narrow spikes relatively near to specific wavelengths, and there are "not very much" other wavelengths present. But recognizing these very pure and saturated colors is not that trivial, and this works only for just those three colors.

 

[Photo Engineer]

Explanation in detail

Here is the complete explanation in figures of additive, subtractive and pigment colors. Make your own decision about yellow! And magenta for that matter!

PE

 

[Ray Rogers]

The Sounds of Slience cannot be heard by the Deaf...

I have a migraine headache comming on so excuse please my ill thought out mumblings!

The above observations by HRST are rather profound...
it is good to contemplate that outside of the human mind, there are no colors... only wavelengths, and things that absorb/reflect wavelengths.
Color is everybit as synthetic as is pleasure, pain, thought and conciousness.
It is our way of being able to interact with the world around us.
We colorize the world so we can make sense of it.

Well, maybe my migraine has me... by the eyeballs!

 

[Photo Engineer]

The material above has nothing to do with film. It is as the eye would see it. Nothing is misleading. If you imply that the prism generated spectrum is wrong, then please explain. If you believe that the additive or subtractive color demos are wrong or misleading, please explain for all of us. This material comes from the Kodak Manual "Color as Seen and Photographed".

Explain please, how it is misleading!

PE

 

[Photo Engineer]

You have not explained, in any way, how the 3 demo photos above are misleading, or how my statement urging others to make their decision is misleading! You just bring in information about photons and energy levels. I was trying to simplify things for the readers and you are trying to kick it up a notch!

PE

 

[Hexavalent]

I have.

But will again, in a way you perhaps better understand?


We are talking about emulsions and their spectral sensitivity.

Are emulsions not spectrally sensitized by dyes? If so, colour addition and subtraction are relevant.

 

[Photo Engineer]

Well, I'll just fall back on the examples.

In fact, I never said anything about passing or stopping anything in that post.

I never said that any filter could change the "color" energy level of a photon. Filters can block or pass photons depending on energy level.

You just seem to want to argue! :munch:

PE

 

[Photo Engineer]

It is directed towards the comments about colors and pigments.

PE