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Apollo Discussions => The Reality of Apollo => Topic started by: Allan F on May 22, 2013, 11:04:34 AM

Title: Radiation and photographic film
Post by: Allan F on May 22, 2013, 11:04:34 AM
I've been wondering, how much the radiation and the photographic film interacted on the Apollo travels. As I see it, there are 3 distinct environments, which need to be taken into account:

1: Film in magazines, in boxes, in the LM, in the Van Allen Belts
2: Film in magazines, in boxes, in the LM, in free space or on the moon
3: Film in magazines, on the surface of the moon

Is there any way to compare the radioactive dose absorbed by the film, to the amount of light energy needed to darken the film by, say, 50%?

In order to do this, the effects of various types of radiation, and it's interaction with the materials between the film and the various environments need to be understood, and the time in each environment need to be understood.

For simplicity's sake, I'll assume each photographic magazine was outside the LM on the surface for the endurance of a moonwalk, about 8 hours, the traverse of the Van Allen Belts were 1 hour in each direction, and the total of free space and lunar surface ops were 12 days 1 hour. That's the duration for Apollo 17, btw.

What I need is an understanding of the particle-to-x-ray conversion and the attenuation by the various materials between space and film.

Edit: My initial assesment, based on nothing but my years spent as a photo-amateur, makes me believe, that the film used, protected as it were, would survive several moon trips without being significantly damaged.
Title: Re: Radiation and photographic film
Post by: ChrLz on May 25, 2013, 08:17:46 AM
I've been wondering, how much the radiation and the photographic film interacted on the Apollo travels.
Why?  I'm not trying to be smart or suggest you are a secret Apollo Denier, but I'm interested..

Maybe someone else here (JayW?) can elaborate further, and maybe there is a way to do this meaningfully, but I doubt it and I'm going to take a slightly contrary view..

Quote
As I see it, there are 3 distinct environments, which need to be taken into account:
1: Film in magazines, in boxes, in the LM, in the Van Allen Belts
2: Film in magazines, in boxes, in the LM, in free space or on the moon
3: Film in magazines, on the surface of the moon
Well, yes, I guess that's a starting point, but.. even that is over-simplifying it - what about when the cameras were in shadow?  Astronaut shadow versus LM shadow?  Near ground or at chest height?  Etc, etc..

Quote
Is there any way to compare the radioactive dose absorbed by the film, to the amount of light energy needed to darken the film by, say, 50%?
Effectively impossible, I'd guess.  Light is, after all, a small subset of the total radiation..  and you have radiation both above and below the visible light range and all of it interacts differently with the camera body itself and then the multiple photosensitive film layers and the base emulsion, and of course then there's the film which is still wound prior to being exposed versus the frames at or near the light chamber and the interactions with the backplate and the reseau plates, versus that which is wound onto the takeup spool on the other side of the cartridge...  There's also the fact that the chemical nature of the film has changed *after* it is exposed, so you'd havta do it twice...

Quote
In order to do this, the effects of various types of radiation, and it's interaction with the materials between the film and the various environments need to be understood, and the time in each environment need to be understood.
No, I'd argue that they actually don't need to be understood in the sense of some sort of accurate theoretical evaluation..  What I mean is, rather than agonise yourself to a possible early grave by trying to work out some meaningful way to come up with a number that would probably be wildly inaccurate due to the enormous complexity and variability of the situation, why not use a basic understanding and a ballpark idea, and then just take the cameras up into orbit and try them out and see what happens..?  (Phew - I knew I shouldn't have held my breath as I typed that sentence..:D)  Which is pretty much what they did.  After all, we have a fairly good understanding of how film is affected down here on earth in hot/cold environments, at high altitudes, over long periods.  We also know how the radiation varies once you get into orbit and beyond, and most of this was pretty well tested and understood (eg Gemini) before A11 made it for the real thing.

Quote
For simplicity's sake..
I don't think any attempt to do this in that fashion would be remotely 'simple'..  You'll find light sensitivity curves for the film easily, and then maybe susceptibility to xray (eg airport xray) type radiation, but extended radiation sensitivity?  That would probably involve materials scientists with very sophisticated and expensive equipment, rather than Kodak or Hasselblad..  So why not just take the cameras up on missions and try them out and look carefully at the results?  Which is what they did.

Frankly, it just wasn't that much of an issue, in the same way that radiation in general wasn't a big deal for these short missions (barring intense solar activity..)...

Quote
Edit: My initial assesment, based on nothing but my years spent as a photo-amateur, makes me believe, that the film used, protected as it were, would survive several moon trips without being significantly damaged.
While I agree and the evidence suggests you are right, earthly experience doesn't count for much in space.  And in this case, I don't think there is/was any substitute for simply testing it out in the actual environment..
Title: Re: Radiation and photographic film
Post by: Allan F on May 25, 2013, 10:23:40 AM
The reason for my question is the simple, that on another forum, I came up against a person, who claimed all the apollo photos are bogus, because radiation in space would destroy the film.

Obviously, it didn't. Now, for my own amusement, and in order to have my gun loaded for the next zombie attack, I wondered, if someone here had the info I'm seeking.

Please, don't wonder about my opinion about Apollo. There is no doubt, in my mind or in my words, that the historical account is accurate, to within the limits of human understanding. Some errors, like misnumbered photos may have snuck in, most errors are in the post-processing, like overdubbing video with wrong sound. And that's the fault of the tv-company, doing the documentary you view.

Edit: I did a rough calculation, based on some wildly inaccurate assumptions, that the amount of radiation received by the film (and absorbed) was equivalent to 1/4000 of the energy needed to blacken the film by 50%. I won't even post my calculations, because I could be a factor 100 wrong in both directions.
Title: Re: Radiation and photographic film
Post by: ChrLz on May 25, 2013, 10:55:55 AM
The reason for my question is the simple, that on another forum, I came up against a person, who claimed all the apollo photos are bogus, because radiation in space would destroy the film.
Ah, I see...  May I suggest that you offer to help him work through this *properly*..  First, as he clearly knows about this stuff :D, ask for the types/wavelengths and intensities of radiation that would exist on the Moon to destroy the film, and where he got his figures.  If he doesn't have them to hand, you could suggest some ways he could research those figures, while at the same time expressing extreme puzzlement as to:
1. Why he didn't do that first..
2. In the absence of such numbers, what on earthmoon he based his 'opinion' on (other than his deep desire to believe in a conspiracy..)

I don't think the conversation will get much further..
Title: Re: Radiation and photographic film
Post by: Allan F on May 25, 2013, 11:11:29 AM
That's what I did - and it has been dragging on for about 2 weeks now. Everytime I ask a pertinent question, I get foul language in return.

Example: I asked: "AND you still have to quantify the amount of your particles - one particle on the entire journey won't cause enough radiation to make a spot on even unshielded film. You need to tell us the number of particles in a cubic centimeter"

and got: "The number of particles is E = MC2 to the 33rd power x the number of Freemasons on the US Fed board by birth, divided by their greed & contempt for constitutional normalities, then multiplied by the collective debt of the US Taxpayer over their US Federal Deficit after the entire NASA budget since the faked Apollo landings was added in triplicate. Secondary radiation from high-energy particles from old nova make your Venus photo as impossible as a magic bullet going to Uranus via Dallas Texas."

Earlier, he made some sense, but not much. I'll spare you for his anatomical references,

Edit: Here's the exchange, if you have the time to get a good laugh:
Title: Re: Radiation and photographic film
Post by: Trebor on May 25, 2013, 01:39:43 PM
This might be of use :
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4324793&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4324793 (http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4324793&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4324793)

I have the full paper and can email it if you are unable to get it from there.
Title: Re: Radiation and photographic film
Post by: Allan F on May 26, 2013, 12:43:38 AM
Yes, please, that would be very helpful. Just take my usename, remove the space, and add (at)galnet.dk
Title: Re: Radiation and photographic film
Post by: Allan F on May 26, 2013, 06:08:31 PM
What missions were launched to measure the radiation in space, after Explorer 1 did the initial discovery? Were the particle radiation quantified and how? I'm sure NASA didn't send men beyond LEO without actually having done extensive research first.

Title: Re: Radiation and photographic film
Post by: gwiz on May 27, 2013, 06:39:24 AM
What missions were launched to measure the radiation in space, after Explorer 1 did the initial discovery? Were the particle radiation quantified and how? I'm sure NASA didn't send men beyond LEO without actually having done extensive research first.


Dozens of missions, lots of the Pioneer and Explorer series with the usual variety of radiation sensors, right up to Apollo 4 and 6 with dosimeters to get the crew exposure inside the CM.
Title: Re: Radiation and photographic film
Post by: Noldi400 on May 27, 2013, 08:10:52 PM
What missions were launched to measure the radiation in space, after Explorer 1 did the initial discovery? Were the particle radiation quantified and how? I'm sure NASA didn't send men beyond LEO without actually having done extensive research first.
Isn't it always amazing how some people (not you, Allan F) interpret "concern" as being synonymous with "insurmountable obstacle"?

Edit: Having looked at that exchange now, IMO you're wasting your time.  He's either just being an obvious troll or has bought into notions so far afield they make moon hoax belief seem like a matter of taste.

Besides, if such a "Bell" existed, and people traveled inside it, the shielding they would require for the radiation it supposedly emitted would make anything found in space barely a second thought.
Title: Re: Radiation and photographic film
Post by: Allan F on May 27, 2013, 08:19:14 PM
"But that's difficult!"
"Yes, come back tomorrow!"

It is their inability or unwilling to acknowledge there are smarter and better people than themselves.

Edit: I know I'm above average (scored 156 at mensa, but didn't join), but I still have to look up to a lot of smarter people.
Title: Re: Radiation and photographic film
Post by: Kiwi on May 28, 2013, 11:03:15 AM
I was a professional photographer from the mid 70s to 1989 and a dedicated amateur before that, and examined many photographs for clients of my shop and studio.

There is one thing in some of the online lunar surface photos that intrigues me because I've not seen it in any other transparencies and have not seen any discussion about it, so I wonder if it could be radiation:-- Tiny blue dots.

They could even be artifacts of the scanning process, but being circular, I have to wonder if they are indeed in the original transparencies.  However, they are tiny and difficult to find, so if they are caused by radiation the effect is negligible.

AS11-40-5906 has one of the dots, on the far right edge, in the black sky just above the horizon.  Further down, to the right of the shadows of Buzz's PLSS and right elbow there are three white dots and a pale blue one.  However, there is a lot of glass on the moon so they could just be specular highlights caused by reflections of the sun.
http://www.hq.nasa.gov/alsj/a11/AS11-40-5906HR.jpg

Three more white dots can be seen below and to the left of Jack Schmitt's boots in AS17-40-22158
http://www.hq.nasa.gov/alsj/a17/AS17-145-22158HR.jpg
Title: Re: Radiation and photographic film
Post by: Allan F on May 28, 2013, 11:26:19 AM
Well, a lot of the photograph available are second and sometimes even third generation prints. A lot of opportunities for dust to creep in. Just think about the famous "c"-rock photo - a small piece of dust in the scan/copy process, and off they go.

I'm not sure, but I think an artefact that big (visible) is more likely to be dust, than radiation. The radiation damage should be uniformly distributed all over the film, looking like a slight darkening of the original negative.

Edit: What would be interesting, would be to see consecutive photos from the same roll, and the same copying process.

Edit2: Remember, the energy in ONE single x-ray photon or gamma photon is microscopic, when looking at macroscopic objects. And the photons aren't in any way focused, but very scattered. If it was a radiation event, it would most likely come from a radioactive contaminant, inside the film magazine. And I don't think that's likely.
Title: Re: Radiation and photographic film
Post by: ChrLz on May 28, 2013, 06:00:17 PM
There was a discussion about the blue specks some time ago, and I'm pretty sure that the consensus was that they were simply scratches and other film defects/damage - from lunar regolith particles and possibly even static sparks - when you scratch Ektachrome lightly, you tend to reveal the blue layer iirc..   I'll see if I can find it but not right now, have other stuff I need to do....
Title: Re: Radiation and photographic film
Post by: Allan F on May 28, 2013, 06:40:29 PM
The hasselblad cameras were modified to deal with the static charge between the film and the camera. The scratch idea seems like a good one. The emulsion is very sensitive, especially when it's being processed, and is wet.
Title: Re: Radiation and photographic film
Post by: ChrLz on May 28, 2013, 09:38:37 PM
The hasselblad cameras were modified to deal with the static charge between the film and the camera. The scratch idea seems like a good one. The emulsion is very sensitive, especially when it's being processed, and is wet.
Yep.. - here is a thread on the old board - i think there's a more recent one somewhere.  You'll need to read down to get to the meatier bits:

http://apollohoax.proboards.com/index.cgi?board=theories&action=print&thread=2507 (http://apollohoax.proboards.com/index.cgi?board=theories&action=print&thread=2507)

It's interesting as it dates back to 'GoneToPlaid's first appearance, and marks one of very few occasions when his first thought was not correct...  :D
Title: Re: Radiation and photographic film
Post by: Allan F on May 28, 2013, 11:11:13 PM
Seems reasonable enough.
Title: Re: Radiation and photographic film
Post by: onebigmonkey on May 29, 2013, 12:53:09 AM
One of the interesting things I discovered from looking at Lunar Orbiter photographs is how they photographed the moon.

The probes actually took and developed photographs in lunar orbit. The resulting images were scanned inside the probe and the data sent back by FM signals. So, if the radiation environment of the moon was so lethal to camera film, then these photographs would not exist. Apollo deniers often forget that the missions did not exist in isolation, and a long program of research and development preceded them, and that some of these supposedly insurmountable problems had actually been considered and worked around.

The main concern they had with the film was preventing it become rigid by being in the same place too long, and the 'Photo of the century' (a stunning oblique view of Copernicus crater) is claimed to be a product of taking a photograph purely out of the need to advance the film by a frame to keep things moving.

The Orbiter series also researched micrometeroid impacts, radiation levels under different types of shielding, gravitational differences, and allowed Earth-based radar tracking to be practised.
Title: Re: Radiation and photographic film
Post by: Allan F on May 29, 2013, 06:47:48 AM
By radar-tracking, I suppose you mean radio-based tracking? It would be a lot to ask for a skin-radar-return to be measurable at that distance.
Title: Re: Radiation and photographic film
Post by: ka9q on May 29, 2013, 07:57:17 AM
I'd have to dig up the actual reference, but I'm pretty sure I read that the Lunar Orbiter camera designers chose a very slow film specifically to minimize radiation sensitivity because their missions were much longer than Apollo. This drove much of the rest of the spacecraft design, as slow film tends to require long exposures, which can cause motion blurring if it's not compensated for.
Title: Re: Radiation and photographic film
Post by: ka9q on May 29, 2013, 08:02:13 AM
By radar-tracking, I suppose you mean radio-based tracking? It would be a lot to ask for a skin-radar-return to be measurable at that distance.
That's almost certainly true. Coherent transponders have been the standard since at least that time; they were the basis of Apollo tracking and they weren't new then.

For better or worse, the term 'radar' is often used for range/range-rate systems involving cooperative transponders. The "secondary surveillance radar" on aircraft is transponder-assisted, though it is operated in conjuction with a skin-tracking radar that can be used if the aircraft's transponder is not operating.

The Apollo LM's rendezvous "radar" also relied on a transponder on the CSM.

The only "true" radar that I know of on an Apollo spacecraft was the landing radar on the LM descent stage.
Title: Re: Radiation and photographic film
Post by: raven on May 29, 2013, 11:14:43 AM
It is worth noting Zond 5-8 (unmanned test versions of the Soviet equivalent of the Apollo 8 CSM) took film photographs and returned them to Earth as actual photographs (http://mentallandscape.com/C_CatalogMoon.htm). The means the radiation dosage would be at least similar to Apollo, having travelled through the Van Allen belts both ways.
Title: Re: Radiation and photographic film
Post by: Dalhousie on June 07, 2013, 08:26:04 AM
Luna 3 and Zond 3 also developed film onboard.
Title: Re: Radiation and photographic film
Post by: raven on June 08, 2013, 09:14:24 PM
Luna 3 and Zond 3 also developed film onboard.
As did the prosaically named Lunar Orbiter series.
Title: Re: Radiation and photographic film
Post by: Dalhousie on June 10, 2013, 05:45:09 AM
Luna 3 and Zond 3 also developed film onboard.
As did the prosaically named Lunar Orbiter series.
As already stated in reply 17...
Title: Re: Radiation and photographic film
Post by: raven on June 10, 2013, 12:00:32 PM
Luna 3 and Zond 3 also developed film onboard.
As did the prosaically named Lunar Orbiter series.
As already stated in reply 17...
Oops, my bad. I do know it was a fairly common system at the time, and was even used on some Mars probes I believe, at least on the USSR side of things.
Title: Re: Radiation and photographic film
Post by: Dalhousie on June 11, 2013, 06:39:19 AM
Luna 3 and Zond 3 also developed film onboard.
As did the prosaically named Lunar Orbiter series.
As already stated in reply 17...
Oops, my bad. I do know it was a fairly common system at the time, and was even used on some Mars probes I believe, at least on the USSR side of things.

;)

Zond 3 retransmitted the lunar images at Mars distance, whether this was the stored data or whether the images were rescanned I don't know.
I would assume that all earlier USSR probes also had the same system, although sadly they never had the chance to show their stuff.
Title: Re: Radiation and photographic film
Post by: raven on June 13, 2013, 01:27:02 AM
This page (http://mentallandscape.com/V_Cameras.htm) has some interesting info on Soviet space cameras.
Title: Re: Radiation and photographic film
Post by: BazBear on June 19, 2013, 02:16:06 PM
This page (http://mentallandscape.com/V_Cameras.htm) has some interesting info on Soviet space cameras.
Cool! Thanks for posting that link.
Title: Re: Radiation and photographic film
Post by: raven on June 20, 2013, 12:55:24 AM
My pleasure. :)
Title: Re: Radiation and photographic film
Post by: onebigmonkey on June 20, 2013, 01:27:32 PM
By radar-tracking, I suppose you mean radio-based tracking? It would be a lot to ask for a skin-radar-return to be measurable at that distance.

I've spent most of today trying to track down the original references I read when researching the Orbiter program, and while most of them mention tracking, they aren't very specific about how it was done. You're right of course! Just wish I could find the articles I'd read!
Title: Re: Radiation and photographic film
Post by: bknight on March 24, 2016, 11:20:22 PM
I dug this one up after a poster indicated that all images from Apollo had some radiation artifacts.  I was unaware of any radiation artifacts on any of them, is/was there a minor amount of damage that I have missed or glossed over viewing those images?
Title: Re: Radiation and photographic film
Post by: Allan F on March 25, 2016, 12:46:16 AM
I have never identified any radiation artefacts. There are occasional scratches in the emulsion, some of which appear to have happened in the development process. IF any radiation had reached the film, it would apply a whitish sheen to the pictures - make the black parts slightly grey. And it would be evenly distributed across the film. A single radiation event (a single charged particle or photon) does not carry enough energy to make any visible impression on the film. Only a distributed field of a certain minimum intensity would do anything. I have yet to calculate the light energy needed to affect an ISO 100 film and darken it to the standard 18% (which should be doable, using a combination of shutter speed and apeture known to work in daylight), and then I need some information about how the different types of radiation would affect the film - and of course the attenuation effects of the camera and magazine body. Bob B has already shown how the command module was sufficiently shielded to protect the astronauts - and the film was further protected by being stored in metal boxes.
Title: Re: Radiation and photographic film
Post by: smartcooky on March 25, 2016, 02:41:35 AM
That's what I did - and it has been dragging on for about 2 weeks now. Everytime I ask a pertinent question, I get foul language in return.

Example: I asked: "AND you still have to quantify the amount of your particles - one particle on the entire journey won't cause enough radiation to make a spot on even unshielded film. You need to tell us the number of particles in a cubic centimeter"

and got: "The number of particles is E = MC2 to the 33rd power x the number of Freemasons on the US Fed board by birth, divided by their greed & contempt for constitutional normalities, then multiplied by the collective debt of the US Taxpayer over their US Federal Deficit after the entire NASA budget since the faked Apollo landings was added in triplicate. Secondary radiation from high-energy particles from old nova make your Venus photo as impossible as a magic bullet going to Uranus via Dallas Texas."

If that is the kind of response you get to reasonable questions then you will be wasting your time. This sort of person as a troll (or a nutcase, or both). They will never accept what you have to say no matter what you say.   
Title: Re: Radiation and photographic film
Post by: onebigmonkey on March 25, 2016, 03:29:57 AM
I wonder if they were referring to the 'blue dots' you seen on the images, many of which are mistaken for stars?
Title: Re: Radiation and photographic film
Post by: bknight on March 25, 2016, 08:29:27 AM
I'm not sure, but this is his comments, and he isn't a hoaxer.
Quote
Although you have been told an a number of occasions that ALL APOLLO PHOTOS exhibit some radiation damage
He is arguing with a hoaxer on images.
I'm trying to get the hoaxer to calculate the radiation received during a typical Apollo mission, radiation is his one big hang-up on the missions.

EDIT: changed wording to clarify my sentence.
Title: Re: Radiation and photographic film
Post by: Allan F on March 25, 2016, 05:44:33 PM
I wonder if they were referring to the 'blue dots' you seen on the images, many of which are mistaken for stars?

Those are what I suspect are damage to the photographic emulsion - caused by dragging wet film over an edge or something.
Title: Re: Radiation and photographic film
Post by: ka9q on March 25, 2016, 06:11:40 PM
I wonder if they were referring to the 'blue dots' you seen on the images, many of which are mistaken for stars?
A while ago I proposed that these blue dots were caused by superficial dust scratches on the emulsion of the film.

Color films consist of a sandwich of four emulsion layers on a plastic base (acetate, polyester, etc). The topmost layer (the one closest to the lens) is sensitive to blue light only. Below that is a yellow filter. Next is a layer sensitive to green and blue light, and below that is a layer sensitive to red and blue light.

The yellow filter is needed to remove blue light because all chemical emulsions are sensitive to it. This ensures that the green layer sees only green light, to which it responds, and red light, which it ignores. The red layer on the bottom then responds to the red but not the green.

Ektachrome is a positive process, meaning that the developed image looks like the original (it's not a color negative).

It's also called a "reversal" process, which can be a little confusing; "reversal" refers to reversing the usual film negative to a positive by first developing the exposed silver halide to a metallic silver negative, bleaching out the silver and then fogging and developing the remaining, formerly unexposed silver halide to produce a positive image.

The silver remains as the black in a black and white image, but in color films the silver is only used to trigger the formation of the color dyes that actually form the image; all the silver is ultimately removed. Complementary dyes are formed in each layer: yellow dye in the blue layer, magenta in the green layer and cyan in the red layer.

So if the blue layer in the undeveloped film is removed by scratching, then it will remain clear throughout the development process. If the image is otherwise black, the underlying green and red layers will remain unexposed so after reversal they will produce dense magenta and cyan filters that stop green and red light while passing blue. So the scratch turns into a blue dot.

If the scratch goes through all the layers of the emulsion, it will remain completely clear and appear white after processing. You see those too in many of the Apollo lunar surface images.
Title: Re: Radiation and photographic film
Post by: VQ on March 26, 2016, 02:44:07 AM
I have never identified any radiation artefacts. There are occasional scratches in the emulsion, some of which appear to have happened in the development process. IF any radiation had reached the film, it would apply a whitish sheen to the pictures - make the black parts slightly grey. And it would be evenly distributed across the film. A single radiation event (a single charged particle or photon) does not carry enough energy to make any visible impression on the film. Only a distributed field of a certain minimum intensity would do anything. I have yet to calculate the light energy needed to affect an ISO 100 film and darken it to the standard 18% (which should be doable, using a combination of shutter speed and apeture known to work in daylight), and then I need some information about how the different types of radiation would affect the film - and of course the attenuation effects of the camera and magazine body. Bob B has already shown how the command module was sufficiently shielded to protect the astronauts - and the film was further protected by being stored in metal boxes.

I seem to recall imaging individual beta decays of 35S when helping with biochemistry research (autoradiography). The media with the tracer was pressed tight up against the film. It's been a long while since then and I am a little fuzzy on the details; is the film used for that sort of imaging substantially more sensitive to radiation than the Apollo film?
Title: Re: Radiation and photographic film
Post by: bknight on March 26, 2016, 10:43:22 AM
I wonder if they were referring to the 'blue dots' you seen on the images, many of which are mistaken for stars?
A while ago I proposed that these blue dots were caused by superficial dust scratches on the emulsion of the film.

Color films consist of a sandwich of four emulsion layers on a plastic base (acetate, polyester, etc). The topmost layer (the one closest to the lens) is sensitive to blue light only. Below that is a yellow filter. Next is a layer sensitive to green and blue light, and below that is a layer sensitive to red and blue light.

The yellow filter is needed to remove blue light because all chemical emulsions are sensitive to it. This ensures that the green layer sees only green light, to which it responds, and red light, which it ignores. The red layer on the bottom then responds to the red but not the green.

Ektachrome is a positive process, meaning that the developed image looks like the original (it's not a color negative).

It's also called a "reversal" process, which can be a little confusing; "reversal" refers to reversing the usual film negative to a positive by first developing the exposed silver halide to a metallic silver negative, bleaching out the silver and then fogging and developing the remaining, formerly unexposed silver halide to produce a positive image.

The silver remains as the black in a black and white image, but in color films the silver is only used to trigger the formation of the color dyes that actually form the image; all the silver is ultimately removed. Complementary dyes are formed in each layer: yellow dye in the blue layer, magenta in the green layer and cyan in the red layer.

So if the blue layer in the undeveloped film is removed by scratching, then it will remain clear throughout the development process. If the image is otherwise black, the underlying green and red layers will remain unexposed so after reversal they will produce dense magenta and cyan filters that stop green and red light while passing blue. So the scratch turns into a blue dot.

If the scratch goes through all the layers of the emulsion, it will remain completely clear and appear white after processing. You see those too in many of the Apollo lunar surface images.
I have seen the blue dots on some of the images, but never thought they were radiation artifacts, since there were many more images that did not contain a blue dot.  The scratch concept is probably a reasonable guesstimate.
Title: Re: Radiation and photographic film
Post by: bknight on March 29, 2016, 11:24:42 AM
The proponent posted another assertion that all the film has radiation artifacts
Quote
All of the Apollo lunar surface photos show some radiation damage, although this is not obvious with the enhanced versions we usually see on the net or in publications. The problem is that MOST people have never seen a photo with radiation damage, and do not understand that different types of films ( reversal, negative,color, black and white, slow fast..) react to radiation in very different ways..

Any thoughts from the film experts?
Title: Re: Radiation and photographic film
Post by: Allan F on March 29, 2016, 03:25:42 PM

I seem to recall imaging individual beta decays of 35S when helping with biochemistry research (autoradiography). The media with the tracer was pressed tight up against the film. It's been a long while since then and I am a little fuzzy on the details; is the film used for that sort of imaging substantially more sensitive to radiation than the Apollo film?

Problem is, only x-ray/gamma radiation would ever reach the film. Particles like alpha and beta would be stopped by the body of the camera and the lens. Perhaps Bob B. can do us a favor here?
Title: Re: Radiation and photographic film
Post by: Bob B. on March 29, 2016, 06:10:00 PM
Problem is, only x-ray/gamma radiation would ever reach the film. Particles like alpha and beta would be stopped by the body of the camera and the lens. Perhaps Bob B. can do us a favor here?

I don't see a specific question here, so I don't know exactly what I'm being asked to comment on?

Generally speaking, I would expect that beta radiation <1 MeV would be blocked by the camera body and lens.  Alpha radiation wouldn't be a problem at all.  I think it possible that beta radiation >1 MeV could penetrate through to the film, but that would only be an issue when the camera is outside on the lunar surface.  I have no idea how much or how strong beta radiation is in that environment, though I suspect not much.  Soft x-rays should also be easily blocked.  Hard x-rays, if they exist, would be a problem.  Inside the spacecraft, I feel reasonable confident that the film would be plenty safe, even when passing through the Van Allen Belts.

If you want some rough numbers, 1 mm of aluminum will block electrons ≤0.7 MeV, and will attenuate 99.9% of 10 keV x-rays.

That's my 2¢ for what it's worth.  Keep in mind that I'm no expert.
Title: Re: Radiation and photographic film
Post by: bknight on March 29, 2016, 06:51:26 PM

I don't see a specific question here, so I don't know exactly what I'm being asked to comment on?

Generally speaking, I would expect that beta radiation <1 MeV would be blocked by the camera body and lens.  Alpha radiation wouldn't be a problem at all.  I think it possible that beta radiation >1 MeV could penetrate through to the film, but that would only be an issue when the camera is outside on the lunar surface.  I have no idea how much or how strong beta radiation is in that environment, though I suspect not much.  Soft x-rays should also be easily blocked.  Hard x-rays, if they exist, would be a problem.  Inside the spacecraft, I feel reasonable confident that the film would be plenty safe, even when passing through the Van Allen Belts.

If you want some rough numbers, 1 mm of aluminum will block electrons ≤0.7 MeV, and will attenuate 99.9% of 10 keV x-rays.

That's my 2¢ for what it's worth.  Keep in mind that I'm no expert.
The issue is a Apollo proponent is arguing with a hoaxer along with myself, and he(proponent) believes all images have some radiation damage.  See above post, but here it is
Quote
All of the Apollo lunar surface photos show some radiation damage, although this is not obvious with the enhanced versions we usually see on the net or in publications. The problem is that MOST people have never seen a photo with radiation damage, and do not understand that different types of films ( reversal, negative,color, black and white, slow fast..) react to radiation in very different ways..
I never have seen any, but I might hove glossed over any radiation effects, I was just posting the question for our proponent individuals.
Title: Re: Radiation and photographic film
Post by: ka9q on March 29, 2016, 07:11:27 PM
I could envision that cosmic rays might also penetrate the camera or magazine and hit the film, but I've never seen any evidence of that in the Apollo images. I'd expect them to leave white traces, but because the paths are random I'd expect random streaks, not just dots.
Title: Re: Radiation and photographic film
Post by: Bob B. on March 29, 2016, 07:50:39 PM
The issue is a Apollo proponent is arguing with a hoaxer along with myself, and he(proponent) believes all images have some radiation damage.  See above post, but here it is

I understand the general issue being discussed.  That's why I gave a general answer.  However, if I'm being asked to comment on some specific set of circumstances, then that's not clear to me.
Title: Re: Radiation and photographic film
Post by: bknight on March 29, 2016, 10:04:45 PM
I could envision that cosmic rays might also penetrate the camera or magazine and hit the film, but I've never seen any evidence of that in the Apollo images. I'd expect them to leave white traces, but because the paths are random I'd expect random streaks, not just dots.
Either streaks or similar, but I don't remember seeing anything, but I may have glossed over minor radiation effects, I guess that is what the proponent if speaking about.
Title: Re: Radiation and photographic film
Post by: ka9q on March 30, 2016, 03:41:50 AM
If the individual particle energies are insufficient to leave streaks, then I can see how enough of them, over time, might cause a general fogging of the film.
Title: Re: Radiation and photographic film
Post by: smartcooky on March 30, 2016, 04:45:31 AM
For anyone who is really interested in the effects of radiation on the photographic film emulsions used in space-flight there is this very interesting write up... "The Effects of Space Radiation on Flight Film"

http://ston.jsc.NASA.gov/collections/trs/_techrep/CR188427.pdf

"One of the most damaging effects of radiation on photographic film is an increase in base exposure*.  It produces higher minimum densities for negative films and lower maximum densities for reversal films.  Both types of film experience decreased contrast caused by the changes in minimum and maximum densities. 

Minimum densities experience proportionately higher fog levels than higher densities, resulting in an additional loss of contrast.*  Graininess in the shadow regions and compression of the useful density range are also apparent effects of radiation exposure.*  Colour films experience a colour balance shift because the separate emulsion layers in a colour film, which sensitivities are adjusted for proper recording of different spectral regions of visible light, are affected to different degrees by the energy released from ionizing particles. The most effected layers are blue and green."


Given that photographic processing has been a significant part of my profession for the last 20+ years, I consider myself have enough expertise to discuss this passage with some degree of knowledge.

*Base exposure and contrast
Ideally the film base of an unexposed negative film is clear, and that of a fully exposed film is black. This is what creates the contrast in a black & white film; varying degrees of exposure resulting in a varying of shades of grey. However, when the base exposure is compromised with fogging, instead of having a contrast scale that runs from clear to black, it runs from a shade of light grey to a shade of dark grey, so the gap between fully exposed and unexposed is closed, and it can be difficult  to get a true white or black in the prints made from that negative.

However, three are two very important things to consider here

1. Base fogging can be very, very difficult to detect. Even for an expert its not easy, and even then, that expert really needs to have direct access to the original negatives into order to see it.  Any mild base fogging can be compensated for to some extent in the darkroom, it can even be compensated for if duplicate negatives are made from the original negatives

2. Film & Print scanning. ALL the images of Apollo that you see on the web have been scanned, and as soon as you scan negatives or prints, you have the means of minimising the apparent effects of base fogging and restoring the image to something close to what it would have been like if the film base was not fogged.  Here is an example

(https://dl.dropboxusercontent.com/u/98915197/ApolloHoax/1970-fogged.jpg)

This photo is an original, unaltered scan of a single 6 x 4.5 frame from a roll of 120 Tri-X Pan film shot in the 1970s (the roll was found still loaded in the camera in the basement of a house that was being cleaned out). I only processed a year or two ago. It exhibits even but severe base fogging with considerable loss of contrast and lack of detail in the image highlights. 

(https://dl.dropboxusercontent.com/u/98915197/ApolloHoax/1970-contrast.jpg)

This is what it looked like after I used Photoshop's Levels, Contrast & Brightness and Tone Curves adjustments. The base fog is undetectable; if you didn't see the top photo, how would you ever know that the original negative was fogged.

There is also a third thing to consider...

3. The subject The moon would have to be THE most high-contrast environment of all to take photographs in. All the  subject material in the scenery runs from bright white in parts of the lunar surface to the inky-black sky. Its is stark landscape, with no diffusion.

The conclusion I must draw from this is that, even of the film base of the films used in Apollo were fogged by radiation it would be extremely difficult to detect even with access to the original negatives, and impossible to detect just from prints or scans from the films.   
Title: Re: Radiation and photographic film
Post by: bknight on March 30, 2016, 09:56:18 AM
An excellent report, but I wish it would have addressed the Apollo missions, instead of concentrating on the Shuttle missions.