Can someone explain the meaning of "orthopanchromatic" (Acros)?

[Leigh B]

Given that deep red is about 650nm, Acros handles that pretty well.

- Leigh

 

[Bill Burk]

And it doesn't look like a Type A panchromatic either. Looks like Type B

 

[tedr1]

Spectral sensitivity graph for Acros on page 80:

http://www.fujifilmusa.com/shared/bin/ProfessionalFilmDataGuide.pdf

Thank you.

Seems to be panchromatic and is described using that word in the text. (the chart seems to be page 40 not page 80)

 

[Andrew O'Neill]

If you look at its spectral sensitivity graph, it appears to have more sensitivity into blue spectrum than say, HP5. Perhaps that is why they call it orthopanchromatic. It's just as sensitive to red as most panchromatic films....650nm.

 

[Bill Burk]

Dear Sperdynamite,

Based on the published curves, Acros is at least as sensitive to red as other films. I would say even more so. According to the Merriam-Webster site:

Definition of orthopanchromatic
of a panchromatic material

1. : having a color sensitivity most nearly matching that of the eye

Neal Wydra

I think Neal found the definition of orthopanchromatic which applies to Acros.

 

[Bill Burk]

I drew a graph roughly superimposing Type A and Type B panchromatic films' spectral response curves and above that I drew the differences...

The differences between the films tells you the kind of filter you would have to use to make one film act like the other.

Why would you need a green filter? When you have a Type A (old) panchromatic film and wanted the results to look normal. That's why Green filters were important in the old days.

Why would you ever want to use a magenta filter? When you have a Type B (readily-available today) panchromatic film and want to try to re-create the look that early photographers got when they had Type A panchromatic film and didn't use a filter.

I think it would be a neat experiment to use a magenta filter and try for an old look. Since the numbers are logarithmic, and the peak is around 1... the magenta filter that might do the trick might be a 100CC Magenta filter.

 

[AgX]

Bill, you do not know how these spectral sensitivity charts were made up.
So you cannot relate them to filter curves.

 

[flavio81]

I think Neal found the definition of orthopanchromatic which applies to Acros.

The explanation is different. It is a translation error.

The original ACROS datasheet, in japanese, stated that the spectral response was "sakura-chan-kotesu-asahi", which means:

"the quality of panchromatic response good for representing cherry blossom flowers correctly in film, despite caucasian people ending up looking like spending way too much time on a tanning bed."

Which of course describes perfectly Acros 100 spectral response. Japanese people are honest. At the release of Acros 100 the original brochure consisted solely on pictures of Cherry blossom flowers, plus a fine portrait of Muhammad Ali. No other people was portrayed in the brochure.

The english translator thought this meant "correct panchromatic" and thus the english datasheet says ORTHOPANCHROMATIC.

 

[dwross]

Just of bit of additional geek:
From the Focal Encyclopedia of Photography", 1960 edition,
ORTHOPANCHROMATIC. (Correct pan).
Term used to describe materials sensitized to all colors of the visible spectrum but
with an evenly balanced red sensitivity. In this they differ from the excessive red
sensitivity of some high-speed panchromatic emulsions which are produced to give
speed as a first consideration.

 

[AgX]

That is the point.
Another major photo encyclopedia also hints at ortho-panchromatic being the opponent to super-panchromatic, not to panchromatic.

But as I indicated above these terms are vague, as the spectral sinsitations varied over time, but still were designated the same.
Also orthopanchromatic is a term that vanished here for decades and I first saw it re-introduced by Maco.

 

[AgX]

For those who love terms, here a synonym that not yet became fashionable: rectepanchromatic

 

[Nokton48]

A Wratten 47B Tri-Color Blue will give an orthochromatic rendition with panchromatic film.
Old glass wet plates were rather ortho in tonal appearance and gives a somewhat period effect.
I've shot Ilford Commercial and Tri-X Ortho with somewhat similar results.
In portraits it really pumps up the skin tone; you can see every facial imperfection with LF

I've noticed the ortho effect in my photographs taken with Fuji Acros, although it is not a strong an effect as shooting Ilford Commercial

 

[Bill Burk]

Bill, you do not know how these spectral sensitivity charts were made up.
So you cannot relate them to filter curves.

I thought you would agree with the way I approached this, so I'll give a little explanation of what I did...

I drew the curves from the 1942 "Principles of Photographic Reproduction" and those are prints of a spectrograph through a step wedge with "daylight quality" source. Miller acknowledges Kodak for the charts. I have other books that show the device.

I like the older graphs more than the new "clean" graphs because it's not hard to estimate the data points to copy to graph paper.

For the "suggested filter" curves, I only estimated displacement between curves, for example at 460nm the two curves differ by 0.5 because the Type A shows 2.5 and the Type B shows 2

Because I intended to describe the curve of a suggested filter, I displaced the difference graphs to zero (because I was getting negative numbers that wouldn't conceptually work with filters). Then, to illustrate the differences from Type A to B ... and Type B to A... I reflected the curves.

Then I browsed the Kodak Filters for Scientific and Technical Uses booklet, looking for filters which dip in the green/yellow region.... (Kodak No. 11 looks like a good fit) and peak in the green/yellow region... (this looked to me like Magenta CC 100).

I often get fascinated by the idea of simulating an old-style film because I don't get blank skies with 400 TMAX and I never seem to block highlights. So I am curious about the problems photographers used to struggle with, and I am sometimes charmed by old photographs.

 

[Bill Burk]

The explanation is different. It is a translation error.

The original ACROS datasheet, in japanese, stated that the spectral response was "sakura-chan-kotesu-asahi", which means:

"the quality of panchromatic response good for representing cherry blossom flowers correctly in film, despite caucasian people ending up looking like spending way too much time on a tanning bed."

Which of course describes perfectly Acros 100 spectral response. Japanese people are honest.

That's a wonderful story. Literal translation? Or did you add some color of your own?

 

[flavio81]

That's a wonderful story. Literal translation? Or did you add some color of your own?

All of that post is a joke, i know zero japanese.

But i find Acros 100 spectral respose weird.

Also i find the Fomapan films (100,400) to have weird response, being overly sensitive to red. Sometimes it works beautifully, sometimes it does not.

 

[Anon Ymous]

All of that post is a joke, i know zero japanese.

But i find Acros 100 spectral respose weird.

Also i find the Fomapan films (100,400) to have weird response, being overly sensitive to red. Sometimes it works beautifully, sometimes it does not.

The spectral sensitivity curves of the Foma films were produced with a 2850K or thereabouts light source, while the Acros curve with 5400K. These aren't directly comparable and makes Foma films seem very sensitive to the red end of the spectrum.

 

[NedL]

Qualitatively, here is what I like about acros:

I can get great clouds in a blue or light blue sky without any filters. If you do need to burn in a sky to bring out cloud detail, it does not create exaggerated grain in the sky. It's safe to give a little extra exposure because the highlights won't blow out.

If there are different kinds of green in the scene ( different kinds of trees for example ), the different green tones separate from each other beautifully.

I don't have a lot of experience with lots of different kinds of film, but I know that with FP-4 I often get better skies with a yellow filter, and with tri-x a yellow-green filter can help separate those greens ( but light greens, like spring grass, can become very light, almost like IR ). Neither of these behaves like acros if you don't use a filter.

So I like acros because it does a lot of what I like without any filters at all. I'm finding that Adox CHS II is very similar... it also does well with clouds and separates different green tones nicely. I haven't worked with it enough yet to be confident, but I already know that I like both acros and CHS II.

I've played with a blue 47b and so far, for whatever reason, I like it best with tri-x. The extra speed surely doesn't hurt! In my mind, I associate "orthopan" with great separation of green tones AND nice skies, I associate blue-only with beautiful atmospheric effects, blown skies, and an old fashioned look that makes everything seem like it is inside the light-filled air...... which IMHO is MUCH closer to what the world looks like with our own eyes. Both wonderful but for different things....

Happy New Year!

 

[flavio81]

The spectral sensitivity curves of the Foma films were produced with a 2850K or thereabouts light source, while the Acros curve with 5400K. These aren't directly comparable and makes Foma films seem very sensitive to the red end of the spectrum.

Thanks Syd for the explanation. Sounds logical. However, everytime i've used fomapan, i can't help but notice the significantly different color response.

 

[Gerald C Koch]

A Wratten 47B Tri-Color Blue will give an orthochromatic rendition with panchromatic film.
Old glass wet plates were rather ortho in tonal appearance and gives a somewhat period effect.
I've shot Ilford Commercial and Tri-X Ortho with somewhat similar results.
In portraits it really pumps up the skin tone; you can see every facial imperfection with LF

I've noticed the ortho effect in my photographs taken with Fuji Acros, although it is not a strong an effect as shooting Ilford Commercial

Actually not. To simulate the response of orthochromatic film you must use a minus-red filter which is cyan in color. You can see this from the color wheel where cyan is the compliment of red. It will pass blue, green and yellow but not red. A blue filter will simulate an unsensitized emulsion which is blind to all colors except blue and violet. Think of old wet plate prints such as those of Matthew Brady. Everyone appears to be wearing black clothing.

 

[removed account4]

Actually not. To simulate the response of orthochromatic film you must use a minus-red filter which is cyan in color. You can see this from the color wheel where cyan is the compliment of red. It will pass blue, green and yellow but not red. A blue filter will simulate an unsensitized emulsion which is blind to all colors except blue and violet. Think of old wet plate prints such as those of Matthew Brady. Everyone appears to be wearing black clothing.

would the cyan filter be the same as using poly regular old photo paper rather than film,
not too fancy an emulsion, but a bromide / bromide iodide emulsion ... something found
in the bottled emulsions sold by rockland colloid, foma or through the recipes on denise ross' website thelightfarm.com ?

there's lots of different "ortho" as mentioned by the link i first posted.

 

[Gerald C Koch]

You would probably be good using a fixed grade paper. They are blind to yellow and red. You can use such a safelight. VC contrast papers do contain a sensitizing dyes.

 

[NedL]

This brings up questions I've been wondering about for a long time, but I don't want to derail the thread. But there is surely contradictory information on APUG about whether silver iodide is red sensitive or not... it can be another thread to start off the new year. Happy New Year to all of you!

 

[Leigh B]

It will pass blue, green and yellow but not red.

Interesting contradiction.

Since YELLOW = RED + GREEN.

How can it pass YELLOW and GREEN but not RED ? ? ?

- Leigh

 

[Bill Burk]

Red light is blocked by a cyan filter...

As yellow light passes through the cyan filter, the red gets blocked. Cyan filter allows through the green part of the yellow.

 

[Bill Burk]

To recap what I understand from this thread so far...

Leigh B has experience with Acros so I trust anything he says about how it behaves. Listen to Leigh B when he talks about subtle differences.

Acros is not an "ortho" film.

The term "orthopanchromatic" is a confusing term.

If you are looking to simulate an Ortho film, try a cyan (or blue) filter.

If you are looking to simulate a Type A pan film, try a magenta filter. (Because I have it, I am going to try an FL-D filter which has a magenta appearance).