Hiya

I've been involved in a discussion on another forum, where people have been repeating the same tired old arguments about how the Apollo landings were faked. I have managed to put right all of their problems so far, but the quote below contains things I am not too sure about, mainly because my knowledge of photography isn't too hot. I am able to respond in broad terms, but cannot respond to specific details. Can anybody with better photographic knowledge than me (which has got to be most people) find fault with the details he provides? I suspect he's copied it directly off a conspiracy website, because the writing style is not consistent with that of his other posts, so there may be an almost "official" response to this somewhere (I can't find it).

Welcome to the BABB, Lianachan!

The picture in question:
http://www.hq.nasa.gov/alsj/a11/as11-40-5961.jpg

Apollo 11 only caried one camera on the lunar surface and this was equipped with a standard objective. The 500mm was taken first time with Apollo 15.

That lines converge has nothing to do with wide- or tele-lenses (though the effect is emphasized with the wide-angle). It's just a matter of perspective.
When you stand between railroad tracks, no matter what objective you use, the tracks will converge. Tha's absolutely cheapo perspective.

The other questions I leave for Jay...


Harald

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"Flying in space is risky business, but just staying on this planet is risky business too." - John Young, astronaut

Thanks for that. I had already explained about the shadows, and about perspective, but it hadn't even occured to me that the camera he's been talking about was not used to take the pictures he's been talking about.

The writer is incorrect when he describes the time of (lunar) day. All the Apollo landings took place in the early morning (local solar time). The sun angle was typically about 15 degrees above the horizon. There were no lunar photographs taken near local noon or "early afternoon", because in every case the astronauts had already left by then.

The "dark horizon" question is readily explained, as is the fact that not every photo shows this effect. On rough terrain (and the Moon's surface definitely qualifies), when you look up-sun (that is, generally toward the sun), you see the shadowed side of objects. This becomes more true toward the horizon due to foreshortening (perspective again). This is easy to reproduce here on Earth, though it's somewhat less dramatic because the shadows get some backfill due to atmospheric scattering.

Naturally, the opposite is true when you look "down-sun", that is, with the Sun behind you. Therefore, down-sun shots show a bright horizon.

He states,

"I've taken thousands of bright afternoon landscape shots with ALL focal lengths clear down to 16mm fisheye lenses with all exposures and I have NEVER had a horizon be darker than the rest of the image except when I used a wide angle lense with 3 or more stacked filters on the lense but even that creates a dark Halo around the entire image. "

Ask him to post some of those photographs so that you can review them. I've found that usually when some hoax believer states that they did something, they usually didn't do that.

Welcome, Lianachan!

This is a complete nonsense. The focal length affects only the degree of convergence, i.e. how much the shadows will converge. Regardless of focal length, you'll still see some convergence, though the amount decreases with longer focal lengths. This is self-evident to anyone who has been dealing with perspective in photography, art, ray tracing or just geometric optics in general.

Lunar morning, actually. And since they didn't spend more than a few days at a time, it was lunar morning throughout the mission.

However:
AS-11-40-5961 is a down-sun photo. No darkening at the horizon.
AS11-40-5942 is a cross-sun photo. Slight darkening at the horizon
AS11-40-5872 is somewhat up-sun. The darkening is slightly more emphasised.

See the pattern? The lunar regolith is somewhat peculiar in this respect - it tends to reflect more light backwards in the direction the light came from. This means that lighting will be brighter and more uniform when the camera is pointed down-sun, and get more angle-dependant and murkier when pointed up-sun. This can be seen from your own back yard, in fact - check the brightness of the moon at 2nd quarter, 3rd quarter and at full moon - the moon is dramatically brighter at full moon, when you're looking at it along about the same the line the light is coming from; much more than twice as bright as during half moon.

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"We do not require reality to conform to the expectations of the ignorant"

Apollo 11 only caried one camera on the lunar surface and this was equipped with a standard objective.

Nope. The lunar surface photos were taken with the 60mm wide-angle. This is one technical detail that Bennett and Percy actually managed to get right in "Dark Moon."

The Apollo 11 Press Report says that the 80mm was to be used, as do other documents, but somewhere along the line a change was made to the 60mm.

The hoax believer above obviously didn't take his many landscapes on the moon, and he is ignorant of the fact that all lenses will show converging lines -- they are just more noticeable with wide-angle lenses. His comments are yet another example of the "I don't understand and it looks odd to me so it MUST be faked," brigade.

[Do I get the "I corrected Harald Kucharek" teeshirt?]

It's only slightly true that you need a wide-angle lens to get converging shadows. That is, the narrower the field of view, the less likely you'll have a wide enough view to capture shadows that obviously converge due to perspective.

The 80mm lens was on the camera that was kept in the command module, used in orbit while the commander and lunar module pilot were on the surface. The 60mm Zeiss Biogon lens was used on the cameras that took the pictures on the lunar surface. The horizontal and vertical field of view of that camera was on the order of 50 degrees, or about five degrees wider than the generally accepted minimum for wide-angle lenses.

If you research the history of the Biogon lens (which, BTW, you can still buy today for the Hasselblad MK70 -- the modern equivalent of the lunar surface camera) you'll discover that Zeiss certain considers it to be a wide-angle lens.

The notion that the surface should always appear evenly lit all the way to the horizon in photos taken in sunlight is just total hogwash. I have a hard time believing that your friend really has the experience he claims, because photographers very quickly run into problems of even lighting from unidirectional light sources when photographing flat surfaces. That's why we have animation stands and other lighting setups used to try to solve those problems.

The Apollo 11 photographs were most certainly not taken near lunar noon. The sun elevation angle was between 9 and 12 degrees. If you go out to the desert where I live and take pictures in early morning or late evening it's all but impossible to get the terrain to be evenly lit.

In this particular case, when the astronauts are looking up-sun (i.e., toward the sun) they're seeing mostly the shaded sides of the rocks and texture elements, and the shadows cast by the texture. This produces a generally dark appearance. When they're looking down-sun (i.e., in the same direction the light rays travel from the sun) then they're seeing primarily the sunlit sides of texture elements, and the elements and features hide their own shadows. This results in a generally brighter appearance. This effect is more pronounced in a vacuum because the fill light from atmospheric scatter fills in shade and shadow on Earth.

These phase effects are well-studied and the physics behind them is well understood. What we see in the Apollo photographs is exactly what physics predicts we should see. Your friend doesn't know what he's talking about.

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"Facts are stubborn things." --John Adams
Clavius Moon Base

Jay forgot to mention his site. It answers plenty of the hoax believers questions.

It's an excellent site, and I've already linked to it in that discussion (obviously to no avail). If people want to believe something is faked, they'll think any evidence you show them is also faked, and that anybody who appears knowledgeable is somehow "in" on the hoax and is trying to drown you in tham there big wurdz.

Thanks for all replies - all very interesting.

Far too often these arguments have nothing at all to do with evidence. Many hardcore HBs believe what they do because it is what they WANT to believe. They often become so entrenched there is no argument you can make that will get them to change their minds. When that happens you don't make the argument for the sake of the HB, you make it for anyone else who might be reading.

I think it should also be mentioned that with one light source you will never have converging shadows no matter what lens is used. The shadows may "appear" to converge as some from the moon do but will never actually converge.

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"Eternal vigilance is the price of supremacy"
------------Mark Twain

"Women are like Voltron. The more you can hook up, the better it gets."

Is there some demand for something like this? :-)

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"Flying in space is risky business, but just staying on this planet is risky business too." - John Young, astronaut

Frenat, on a flat surface, the shadows will converge to a point on the horizon directly beneath the light source (assuming the camera faces the direction of the light source).

If people want to believe something is faked, they'll think any evidence you show them is also faked...

Of course. Discussions with entrenched people can be frustrating, but as Bob notes it's advantageous to present people with evidence contrary to their beliefs because that's how irrational opinions are identified. I have met many people who believed innocently in the moon hoax simply because the hoax advocates sounded well-reasoned and no one was there to guide them through the facts.

...and that anybody who appears knowledgeable is somehow "in" on the hoax...

The key word there being "somehow". That's where you reveal handwaving and evasion on the part of the hoax believers. They establish a rhetorical framework where, as soon as someone knows enough to speak intelligently about the question, he's "automatically" assumed to be motivated to speak for one side or the other. That is, the conspiracists convert an argument about expertise into an argument about trustworthiness.

That's a calculated ploy. You can never conclusively answer questions about someone's motives. You can argue the presence of influences, but whether those influences have an effect is not answerable. You can, for example, point out that someone works for XYZ Corp., but you can't prove that his actions in any particular point are motivated by concerns arising out of that employment. Conversely, you can note the apparent absence of influences, but you cannot from that assert that no ulterior influence motivates a person's actions.

You can, however, conclusively answer questions about someone's level of understanding. Academic degrees, certificates, licenses, and recognized references can be used to substantiate and document that a person has a requisite level of understanding applicable to a particular problem. At the very least, expertise can be demostrated.

If the conspiracists allow the discussion to center around who is likely to know more about the facts relating to the problem, they know they cannot win. And in fact, they know they will handily lose. But if they can make the argument be about who a reader should trust, they can play the game forever without any fear that it will ever be resolved. They may not be able to win, but the nebulous nature of speculating about motives ensures they will never lose.

...and is trying to drown you in tham there big wurdz.

Well, it's a big universe out there full of details. We as laymen commonly encounter knowledge that has been simplified to our level of understanding. It is a mistake to suppose that a simplification can be used to test authenticity. You can never know whether the "anomaly" or "discrepancy" in an observation is an actual cause for concern, or whether it lies in the gap between simplification and real life.

Expertise exists for a reason. It's not incumbent upon everyone to understand the ins and outs of illumination and the physics of photometry on textured surfaces. If you are a baseball player or a marketing executive or a carpenter for a living, you just don't need to know that. But just because you don't know it doesn't mean there isn't anyone who does. Simplifications can only work if they omit detail. But omitting detail isn't the best thing to do when correctness counts.

Sometimes you need to be simultaneously an expert in different fields to answer particular questions. Your photographer friend is justified in expecting a well-lit horizon when the sun is overhead. He speaks from an empirical point of view, having taken many photographs in that situation and having observed the effects. Theoretically we can say that would be true, because the physics of phase angles works out to support his empiricism. But where your friend falls short is in his knowledge of Apollo's photographic conditions. He's simply wrong about the sun being high in the sky. The sun was very low in the sky, and that changes the expectations.

And that's at the heart of the problem. How do you know that what you expect to see is actually what you're going to see? If you go into that battle armed only with oversimplified summaries of the relevant physical laws and the relevant facts, your expectations won't necessarily be valid. And if they aren't, how can you hope to pass judgment on whether something is real or not?

So the question in determining authenticity is not whether the laymen are stumped, but whether the experts are stumped.

Ironically, the dismissal of expertise in conspiracist reasoning is largely hypocritical. They don't dispute the value of expertise. They simply claim to have it when they really don't. They acknowledge that expertise is required. But to get that item of credibility they either inflate their own credentials so as to appear to have it, or say that "common sense" provides enough expertise to answer the question -- i.e., that anyone can be an expert.

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"Facts are stubborn things." --John Adams
Clavius Moon Base

I think there is some confusion over convergence and divergence and in what context those terms are intended.

Shadows can diverge in the sense that they are the product of diverging rays from a local point light source. If you establish a line in three dimensional space between the light source and some reference point on an object (say, the tip of a post driven vertically into flat, level ground), distributing those reference points around the scene creates a series of divergent rays. In our contrived situation of geometrically faithful shadows, those shadows will all tend to diverge in the sense that the shadow direction in the plane of the receiving surface -- as reckoned from the point where the object intersects the surface toward the extremity of the shadow on the surface -- for collections of nearby objects, will tend diverge under most circumstances.

That is a tendency only; it holds only in our "pure" model over which we impose certain geometric constraints. Namely, our objects are shaped so as to have a clear, straight longitudinal axis. They intersect a planar surface at right angles to the surface. The light source is singular, nearby, and of negligible size. When we say the shadows diverge, it is with a certain convention of measurement -- from base to tip. And it is measured in affine space -- the actual three-dimensional basis of the scene itself. Relax these constraints and we cannot say as a rule that shadows diverge.

Shadows can be said to converge (i.e., grow closer together) if we apply the projective geometry that governs seeing through lenses. By projecting an image through a lens onto a plane, we can effortlessly create situations where shadows converge in the coordinate system of the image plane. That is, if you trace them in the photograph, they will intersect.

That applies even (or rather, especially) to objects lit by an infinitely distant light source casting parallel light rays. In our canonical geometry above, the shadows cast onto the plane will also be parallel as measured in the plane. But by viewing that plane from various angles and thus introducting differences in the projective transformation from 3D space to 2D image space, we create convergences and divergences.

Artists who create shadows by geometric construction are taught the techniques by which various shadow vanishing points are defined. And these may be independent of the vanishing points of the actual geometric objects in the scene. Parallel constructions in physical geometry, when projected, define vanishing points that govern the appearance of the physical geometry in the scene. Parallel constructions in the invisible geometry of light-travel through the scene also define, when projected, their own vanishing points. These vanishing points govern the appearance of shadows.

Canonical, contrived geometric situations like those described above give us the best insight into the behavior of the mathemetics governing the transformation from affine to projective space. But once derived and characterized, those same principles govern more empirical situations such as actual photography. While the results do not intuitively appear to have derived from simple laws, the apparent complexity of real-world shadows derives from the same basic geometrical laws applied to complex physical geometry.

The mistake then comes from assuming that lunar geography and associated photography is not complex physical geometry. The problem, as always, is the oversimplification inherent to conspiracism.

Projecting from 3D to 2D loses an entire dimension's worth of data. This data is not straightforwardly reconstructed from the projection. In fact, an entire branch of study exists for it: photogrammetry. And it is an intensely mathematical pursuit. The problem most amateur photo analysts face without knowing it is their attempts to draw into question elements of the projection (i.e., the photograph) based on conclusions of the affine representation that produced it. Those conclusions, however, rest on data from the projection itself. So in a laughable twist, the amateurs succeed only in pointing out that their "anomaly" is actually only their own inability to reason consistently from the same data set in two different conceptual directions.

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"Facts are stubborn things." --John Adams
Clavius Moon Base

What I meant was the shadow will never converge to the point that they overlap with a single light source.

__________________
"Eternal vigilance is the price of supremacy"
------------Mark Twain

"Women are like Voltron. The more you can hook up, the better it gets."

frenat wrote:
This is a point I make with many HB who state there had to be fill lighting in place. I work partly in a TV studio and every light source throws a shadow. The trick is to use the lights to negate shadows where you don't want shadows. When you look at the floor of the studio for instance you see a shadow from each light most of the time since the camera rarely is pointed at the floor and shadows there do not matter. these multiple shadows often cross one another and illustrate that there is more than one light source. None of this would be easy to do for a "stage" the size of the one required for a fake moon landing and indeed is not evident in any photo. In fact if any shadow is visible from any object in all pics it has only one shadow.

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