Originally published at: Different postcards with the same sky | Boing Boing
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I have some old postcards tucked away, now I’m going to have to find them and see if they’re Dexter cards.
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Clearly the Sky Projector was broken and the photo editing story is just a cover up.
This would be true if it was a P.K. Dick story 
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The sky above the port was the colour of a Dexter postcard.
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Well technically Earth only has one sky…
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I’ve been to most of those places and I can confirm that’s what the sky looks like there.
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When you’re printing 120 postcards on a single layout and every sky is different, managing the ink flow becomes very difficult. An offset press is supplied ink via what its effectively a crevice between a tray full of ink and a roller. Keeping the flow of ink through that crevice is crucial, but if your artwork varies in the amount of cyan or magenta ink needed for each card, leftover ink on the printing blanket from one rotation of the drum will change the color of the image that happens to need that space on the blanket on the next rotation. On a good layout, large, featureless areas of similar color are stacked above each other to help the pressman regulate a common flow of ink over the entire cylinder rotation. Making the skies identical makes it easy to glance at a single sheet and recognize if the ink flow is irregular.
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Wilhelm sky!
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I think the saddest thing is… they would have only had to talk to a photographer who had actually shot film.
The sky tends to be brighter than the ground.
Film, particularly that Koda-Chrome that they were talking about- had absolutely lovely, bright, vibrant colors. It also had a very narrow exposure band; it only held details for about 3-4 stops of light.
The sky tends to be much brighter than the ground. Enough that you had to make a decistion while shooting: do you expose for the sky - and have lovely clouds and underexposed ground with not much detail, or do you expose for the ground, and have lots of shadow detail and nicely exposed ground and people, and really crappy, washed out, overexposed sky?
They chose to have their cake and eat it too. They exposed for the ground - which is the most important part of these photographs - and they used a stock sky to replace the crappy sky that they overexposed.
To a film photographer, it’s obvious; unless they get info from the artists responsible for a different reason. (And there are some techniques that can make this even easier.)
OFF TOPIC GEEKY EXTENSION
This is just me doing the photo geek thing. You don’t need to read any of this. It’s off topic. It’s just me elaborating on a subject that I used to really, really geek out on… 
Unimportant excetera:
So… how can you fix the sky in camera- without darkroom trickery?
There are two easy filters that you could do. A filter was a sheet of glass that you put in front of the camera lens for an effect.
One of these was a graduated filter. It was a sheet of glass that had a tint at one end that gradually got lighter until it was clear on the other end. It reduced how much light was coming through for part of the image, so you could expose the ground right and knock the exposure for the sky down a bit.
The problem is that this was all flat line horizon based. If your photo had a flat line horizon, it worked out pretty well. If your photo was not really flat line horizon based, then it could cause problems because you either had a band of brighter sky on the lowest part of the sky in your photo, or the upper parts of your “ground” objects were darker than the bottom parts of them.
The other thing was polarizing filters. Light is a wave, and it travels in one direction and “wiggles” in a direction that is at a 90* angle to the direction of travel. Sunlight comes into the atmosphere fairly well polarized in one specific direction, meaning it is all traveling in the same direction, and it is all wiggling in the same direction.
Now, when light reflects off of metal or water, it keeps that same polarization - it is still wiggling in the same direction compared to the direction the light is going, but the light is now headed somewhere else. When light bounces off of most other things, it’s polarization gets messed up, and now the light beam is going in a different direction, and it’s wiggling in a different direction than it had been.
A polarizing filter is a filter that blocks most of the light that is wiggling in one direction, but lets most of the light that is wiggling in a different direction through.
So if you take the filter, you can make the sky darker (which really pops clouds), and it also cuts down on the amount of glare you get from water and metal reflections in your photo.
(Another cool thing to do with polarizing filters is to stack two on top of each other. Each filter will have it’s own polarizing direction. If you rotate them against each other, these directions will interact with each other. This will reduce how much light gets through the filters in a surprisingly even and color neutral way.)
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This. I’ve read umpteen articles over the years about how to expose for sky and foreground. In the age of digital, HDR is often a solution, too.
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My first ten years of work were prepress production in print shops, the second ten in doing the same in a digital photography studio. Nowadays I work on web pages, which provides nowhere near the opportunity to geek out over processes, skills, and equipment. I miss that. Nobody like to hear the details of programming if they don’t program.
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So we really are living in a simulation! These photos prove it. 
I used to do something like that! The print company I used to work for back in the mid-90’s to early 2000’s had a number of clients who were estate agents and would supply photos of their various properties. They liked the pics to be fairly bright and appealing, but the photos were often taken on dull, cloudy days. I built up quite a library of ‘found skies’, with lighting from different directions and time of day, and the flat, grey skies were a gift, being very easy to select and separate allowing the new sky to be dropped in, sized and cropped as necessary. A bit of tweaking to brighten the foreground to match, job jobbed! The clients were delighted. 
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I’ve noticed what you said about the sky in photography a few years ago, looking at a batch of vintage black-and-white photos of my city. We’re used to high dynamic range (HDR) today, but our phone cameras do some doctoring with several photos to achieve that. Basically several photos in different exposures.
I’ve noticed the tinted filter you mentioned in a video by Alec on Technology Connections, he’s in the middle of a series about photography and his videos are very detailed even though they are not extremely technical.
Also, polarizing filters are cool. I have a pair of sunglasses with these filters and I can see interesting multi-color effects when looking through the sunglasses and certain glasses (windshields usually), but I’m not sure why it happens.
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