michrassena's comment has it right. 'orthochromatic' was a later term implying that the film represented the 'correct' version of the spectrum, because it was more sensitive to blue light. the term 'panchromatic' was adopted when black and white films eventually approximated visual sensitivity. the history of this spans decades, which is why it can be confusing.
by the late 20th century, 'ortho' meant a monochromatic film or printing paper that was not sensitive to red light, hence it could be handled in a darkroom with a red safe-lite. however, the spectral sensitivity of even standard photo paper today might be greater than the earliest emulsions.
"Orthochromatic" was a fix; it had extended green sensitivity compared to earlier processes/materials (which were usually referred to as "actinic" after ortho was introduced). Ortho was called ortho right from the beginning to distinguish it from what came before.
The extended green sensitivity is what made it right. Or at least somewhat less wrong than things had been. If they'd found a way to create panchromatic plates/film before ortho as we know it happened, the name "orthochromatic" would have been given to that instead.
So why did ortho rule the roost in the darkroom and in process photography when we had "actinic" papers around? (Obviously, panchromatic is out unless you like working in total darkness.) Incandescent lamps for exposure is a big part of the answer. You don't get a lot of blue light out of a glowing filament, and sunlight isn't quite as consistent and reliable as you might want it to be. (And arc lights aren't a lot of fun to work with or around.) Non-repro blue, a pale cyan that humans can easily distinguish but ortho film/paper can't, is most of the rest. Panchromatic can "see" non-repro blue by design, and "actinic" can see it because it's not blue enough to appear white if it's dark enough to see easily (in paste-up, etc.). Non-repro blue, ruby masks and relatively bright safelight made life... well, not exactly easy when compared to, say, a desktop publishing application, but it beat the heck out of constant squinting in the dark, wondering if that thing was really supposed to be there, or if it was a line at all.
Developing film by inspection is a joy. I've developed a lot of ortho 4x5 under red safe light and love it even though I don't need to (my developer exhausts around the same time the film finishes developing so I don't actually need to inspect). I just do it for fun.
Early photographic processes were only sensitive to the blue end of the visible spectrum. It took many years after photography was developed for chemists to create dyes sensitive to red and green.
Using only the blue channel from a color image is an easy shortcut to obtaining the look which is sometimes done to depict someone as rugged, aged, and weathered for artistic effect.
Here's an article on simulating this look digitally, from the same publication.
I'm having trouble seeing this effect. I think I can make out a curved line on the left cheek of the man in this image[0], but I suspect that's actually due to the skin texture left from the tattooing process. Quoth TFA:
> Tā moko is different from ordinary tattooing because chisels (called uhi are used to carve the skin and opposed to using needles and puncturing. As a result, the skin is grooved rather than smooth in the tattoo areas.
(it appears to have been maybe sharpened in software?)
edit to add:
I think chisels are no longer used because 1] it's painful 2] not many people know how to do that anymore -- but they sure do look good, the old way. They used to use a bluer ink, made of caterpillar guts among other things? A painter named Charles Goldie did some great portraits showing that older pigment:
50/50 people assuming you're complaining about the content buried underneath 20 banner ads, 50 overlays, 900 popups, and probably some malware.
Although I guess most people are on desktop with ad blockers. Are there any actual good ones for iOS? I remember support the use case was going to bankrupt the entire industry a few years ago, so surely they must exist?
I'm still not convinced any of the "new" ad formats (replacing popup/under with overlays :( ) actually improve con version rates, or whether people are accidentally clicking on the ads while trying to make the accursed overlays go away.
The wet plate collodion process is only sensitive to blue/UV light. Those tattoos must fall elsewhere in the spectrum.
As an aside, I've just started doing them myself and it's clear why there's been a resurgence. Scans don't really do them justice, and the aforementioned sensitivity makes freckles/other features really stand out. It's also really hard, and takes a good 5-10 minutes per shot.
The photographic process used is only sensitive to blue/near-UV light. People with dark skin absorb lots of blue/near-UV light. This is why their skin looks darker under this process than it actually is. The tattoos also absorb blue/near-UV light, but the (apparently extra-dark) skin masks the difference, as the contrast ratio between skin covered/not covered with a tattoo is lowered.
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[ 3.3 ms ] story [ 47.9 ms ] threadI must say the effect is strange, it does make the people look darker and more 'foreign' (from a Europeans perspective)
I wonder what effect photos like this had on perpetuating colonialism by making the natives appear less like themselves (the colonists).
[0] https://en.wikipedia.org/wiki/Collodion_process
I think the effect is a bit like what infrared photography does to freckles: https://petapixel.com/2015/09/28/this-is-what-infrared-photo...
by the late 20th century, 'ortho' meant a monochromatic film or printing paper that was not sensitive to red light, hence it could be handled in a darkroom with a red safe-lite. however, the spectral sensitivity of even standard photo paper today might be greater than the earliest emulsions.
The extended green sensitivity is what made it right. Or at least somewhat less wrong than things had been. If they'd found a way to create panchromatic plates/film before ortho as we know it happened, the name "orthochromatic" would have been given to that instead.
So why did ortho rule the roost in the darkroom and in process photography when we had "actinic" papers around? (Obviously, panchromatic is out unless you like working in total darkness.) Incandescent lamps for exposure is a big part of the answer. You don't get a lot of blue light out of a glowing filament, and sunlight isn't quite as consistent and reliable as you might want it to be. (And arc lights aren't a lot of fun to work with or around.) Non-repro blue, a pale cyan that humans can easily distinguish but ortho film/paper can't, is most of the rest. Panchromatic can "see" non-repro blue by design, and "actinic" can see it because it's not blue enough to appear white if it's dark enough to see easily (in paste-up, etc.). Non-repro blue, ruby masks and relatively bright safelight made life... well, not exactly easy when compared to, say, a desktop publishing application, but it beat the heck out of constant squinting in the dark, wondering if that thing was really supposed to be there, or if it was a line at all.
Using only the blue channel from a color image is an easy shortcut to obtaining the look which is sometimes done to depict someone as rugged, aged, and weathered for artistic effect.
Here's an article on simulating this look digitally, from the same publication.
https://petapixel.com/2019/04/05/recreating-the-look-of-1850...
Could we use these as templates to recover tattoos in photos from the time-period the article mentions?
> Tā moko is different from ordinary tattooing because chisels (called uhi are used to carve the skin and opposed to using needles and puncturing. As a result, the skin is grooved rather than smooth in the tattoo areas.
[0]: https://petapixel.com/assets/uploads/2018/07/7.jpg
Super clear photo of the old result: https://scontent-yyz1-1.cdninstagram.com/vp/b80fdf49074ae5b4...
(it appears to have been maybe sharpened in software?)
edit to add:
I think chisels are no longer used because 1] it's painful 2] not many people know how to do that anymore -- but they sure do look good, the old way. They used to use a bluer ink, made of caterpillar guts among other things? A painter named Charles Goldie did some great portraits showing that older pigment:
https://i.pinimg.com/736x/c5/52/82/c55282ddab815e9e4d9d7f2d8...
https://www.nzgeo.com/wp-content/uploads/1998/04/38_Goldie_1...
https://s3.amazonaws.com/img.aasd.com.au/86317163.jpg
https://images.internationalartcentre.co.nz/_auctions/2018/2...
and many many more
And some trivia, moko were occasionally used as signatures on old deeds and treaties, since moko identified the bearer and no two were the same: https://c8.alamy.com/comp/PM1Y2X/image-from-page-41-of-moko-...
e: wow for a community that loves to talk about dark patterns you really seem to suck it up and drop all such considerations when it suits you
Although I guess most people are on desktop with ad blockers. Are there any actual good ones for iOS? I remember support the use case was going to bankrupt the entire industry a few years ago, so surely they must exist?
I'm still not convinced any of the "new" ad formats (replacing popup/under with overlays :( ) actually improve con version rates, or whether people are accidentally clicking on the ads while trying to make the accursed overlays go away.
As an aside, I've just started doing them myself and it's clear why there's been a resurgence. Scans don't really do them justice, and the aforementioned sensitivity makes freckles/other features really stand out. It's also really hard, and takes a good 5-10 minutes per shot.
The photographic process used is only sensitive to blue/near-UV light. People with dark skin absorb lots of blue/near-UV light. This is why their skin looks darker under this process than it actually is. The tattoos also absorb blue/near-UV light, but the (apparently extra-dark) skin masks the difference, as the contrast ratio between skin covered/not covered with a tattoo is lowered.