Author Topic: How NOT to think like a CT, and a sudden understanding of what they feel  (Read 1273 times)

Offline bknight

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I remember some idiot on Y Tube recently proclaiming that the taking of the permission images was proof that all the images were taken on Earth prior to the launch of each mission. ::)
Truth needs no defense.  Nobody can take those footsteps I made on the surface of the moon away from me.
Eugene Cernan

Offline raven

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I remember some idiot on Y Tube recently proclaiming that the taking of the permission images was proof that all the images were taken on Earth prior to the launch of each mission. ::)
Oh dear Lord . . . that's like the idiots who think the shots of the Apollo astronauts in training for surface EVA while in simulated gear is proof of fakery. Schmendrick putzes.  :P

Offline jfb

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Just remembered another possible reason why they used B&W film...

Color negatives and transparencies will fade over time; after processing, all the silver has been washed out of the film, so all that's left behind is dye in the different color layers.  With proper storage and handling those images should last for many, many more decades, but every time they take them out to rescan or reprint, that dye will fade ever so slightly.  Even better, the different layers fade at different rates, so you wind up with weird color shifts (have a lot of old Kodachrome slides that have gone reddish-orange over time). 

With B&W film, the silver isn't washed out after processing, so B&W negatives and transparencies will retain their images until the film itself disintegrates. 

Offline sandopan

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Some errors in development can be dealt with at the printing stage with by using different contrast or color correction filters, different paper, dodging and burning, etc.  I had a couple of rolls that were severely underdeveloped and very "thin", and getting a good final image required non-trivial amounts of manipulation.  But if you blow highlights or lose details in the shadows, they're gone forever. 

I've had some "errors" corrected when making enlargements, when the "error" was precisely the reason I thought it was a nice photo (for example, a faint reflection off of a smooth surface).   >:(

So would I be correct to assume that space photography is all digital these days?
Don't commit terrorism.  Washington hates competition.

Offline JayUtah

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So would I be correct to assume that space photography is all digital these days?

Yes.  Ordinary digital photography samples three discrete wavelengths:  red, green, and blue.  As a matter of practice, sensors employ twice as many green sensors as either red or blue, because that's smack in the center of the visible spectrum.  Digital space photography -- and really any digital imaging for purposes of gathering scientific data -- happens over a wide variety of discrete wavelengths, not all of them in the visible spectrum.  Ironically this sometimes results in problems producing true color images.  It's well-plowed territory to be able to construct a facsimile of a true-color image from red, green, and blue that's faithful enough to real life to qualify as accurate photography.  That has mostly to do with what wavelengths your eyes actually see.  The data that's missing in the RGB image is not necessarily data that your eye would have seen anyway.  But when your image consists of oddball wavelengths.  Say you have an image that has an infrared channel but not actual visible red channel.  You might think to just depict the infrared channel using red pixels, but the resulting image wouldn't look the same as if you'd simply taken it with a normal DSLR.  But scientific photography isn't always about producing attractive true-color images.  Image data from various wavelengths can be combined algorithmically to reveal much more about the scene than ordinary photography -- much more than what the naked eye would see.
"Facts are stubborn things." --John Adams

Offline Bryanpoprobson

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Jay, do they ever use secondary filters Magenta, Cyan, Yellow? As I recall from my pre-digital days every enlarger I ever had, used additive secondary filtration. 
"Wise men speak because they have something to say!" "Fools speak, because they have to say something!" (Plato)

Offline JayUtah

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Not as such, since the sciences generally have wholly different needs than color process.
"Facts are stubborn things." --John Adams

Offline raven

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Let's be honest, some of it was probably for propaganda.  The red, white and blue looks a lot better than the grey, white, and different grey. Of course, by now, they're probably bleached white.
'Come in peace for all mankind', indeed!