ALSJ AND PHILL PARKER

NASA: AS16-116-18716. ANNOTATIONS BY CLAVIUS

What are those little crosshairs in Apollo photographs?

A reseau grid is used in the science of photogrammetry for establishing a geometrical basis for measuring objects in photographs. It can be used to correct for any misalignment of the film in the camera, or distortions in the image after development or electronic scanning. Since the location of the marks on the reseau plate is known with great precision, correcting for distortion is a simple matter of manipulating the image until the marks are in the correct location.

If you take several photographs of an object from different angles, and locate the features of that object in relation to the fiducials, and you know something about the design of the camera, you can actually reconstruct the three-dimensional geometry of the object. This is what photogrammetry tries to do.

The photo above shows a standard Hasselblad 500/EL Data Camera with the film magazine removed to display the reseau plate. There is a large fiducial in the center, and two rows of fiducials above and below, left and right of the center.

NASA claims they're for measuring distances.

NASA spokesman Brian Welch has been quoted as saying you could measure things in the photos by using the fiducials and knowing something about how the photo was taken. This is a clear reference to the science of photogrammetry, for which the reseau plate was provided. However, since the astronauts didn't take multiple photos of everything, especially in early missions, it's not possible to perform photogrammetric analysis on every Apollo photograph.

NASA photo analysts frequently locate details in photos using the fiducials as a reference grid. In recent times this has become the primary function of the reseau grid.

Hasselblad representatives claim the crosshairs couldn't be used for measuring distances. [David Percy]

Mr. Jan Lundberg was the Hasselblad engineer responsible for modifying the company's 500/EL Data Camera for use on the moon. In the video What Happened on the Moon? David Percy asked Lundberg if the fiducials could be used for measuring photographed objects (i.e., photogrammetry). Lundberg replies that they cannot, and that multiple camera angles (e.g., stereo pairs) would be necessary to do that.

Both Welch and Lundberg are clearly referring to photogrammetry in their responses, but a viewer of Mr. Percy's video isn't likely to make that connection. Welch and Lundberg qualify their answers, and Percy doesn't follow up on the details of those qualifications. Welch doesn't give a complete treatise on photogrammetry, and Lundberg (and the viewer) isn't told that the astronauts took many, many stereo pairs with the Hasselblad cameras in order to provide a valid set of data for photogrammetric analysis.

Percy is clearly trying to make it look like NASA spokesmen and industry experts disagree on the purpose of the reseau grid, but in fact their answers both make perfect sense to someone who has studied photogrammetry.

In some photographs the large crosshair is not centered, and in others the grid is not aligned with the image boundaries. If they were added later (i.e., after retouching or composing them in a photo lab), this would explain the misalignment.

The Hasselblad cameras took square pictures. Each image on the film is 70 x 70 millimeters. But most photo formats today are not square, such as 4x6 inch prints common to amateur 35mm photography.

Many of the photographs obtained from NASA are cropped to conform to modern standard formats. The photo lab will compose the crop so as to remove extraneous parts of the picture and retain or feature the intended subject. In addition many cropped photos are available on the Internet, including many here on Clavius. Very few Apollo photos are presented in their original composition. A cropped photo isn't expected to retain the large fiducial in the center.

Since the Hasselbad cameras had no viewfinders, many pictures are tilted or otherwise badly composed. Very often these photos are rotated to render the horizon horiztontal, for example, or to align some feature in the photo to the viewer's expectations. Then the photo is cropped to a correctly oriented square or rectangle. The reseau grid would not align with the photo's borders when this happens.

NASA: AS11-40-5903. ANNOTATIONS BY CLAVIUS

Here is the classic photograph of Buzz Aldrin as frequently reproduced in books and magazines. The white outline shows the boundaries of the original photograph. Even "official" scans from NASA are often framed this way because the natural inclination is to give Aldrin a bit more headroom, and it's often very difficult to tell where the blackness of the lunar sky ends and the blackness of the surrounding film or JPEG begins.

If one wishes to postulate a process by which the Apollo photos were falsified, then it's certainly possible to include a step whereby a large transparent sheet containing the reseau grid is placed over the completed pasted-up photo to create the final master negative. However, it would be awkward to do it that way. The best way to produce the reseau grid after the fact would be as was done in the Hasselblad design. The process camera that took the final picture would simply have a glass plate on the focal plane etched with the reseau grid. It would be much easier to do it that way than to hand-align it for each of the thousands of photographs that had to be produced.

This is a good example of the ad hoc arguments of the conspiracists. They concentrate on how their proposal would produce the observed characteristics without considering whether it's a practical way to falsify the photos.

The crosshairs are partially covered in some photographs. This suggests that the photographs were composed by cutting and pasting objects over the background images, obscuring the crosshairs in the process.

Conspiracists give examples like this one to illustrate their point. The one most often cited is the low-gain antenna of the lunar rover in AS16-107-17446, which appears to lie cleanly atop the fiducial as if it had been pasted over the top. To the layman it seems the most natural conclusion.

But photographers know another explanation. When photographic film is brightly exposed, it is common for these areas of high exposure to bleed slightly into adjacent parts of the picture. This is called "emulsion burn". When we look at the photographic exposures given in the flight plan, we can determine that the photos were probably slightly overexposed. In uncertain lighting conditions, overexposing is the correct thing to do.

If we look at all the Apollo photos where the fiducials disappear, we find they correspond in all cases to areas of high photographic exposure (i.e., bright white areas of the photograph).

NASA: AS-XX-XXXX

NASA: AS-XX-XXXX

NASA: AS-XX-XXXX

In the examples above, the fiducial fades out and then reappears within the area of the image occupied by a single object. Unlike the examples cited by conspiracists, which make it appear that the fiducial disappears behind entire objects, these examples clearly show that the fiducials are obscured where the film emulsion has been saturated. There are also several photos in which the fiducials are simply very faint, not completely obscured.

The fiducials are very thin, only about 0.004 inch thick (0.1 mm). The emulsion would only have to bleed about half that much -- less than the thickness of a human hair -- in order to completely obscure the fiducial. Because of the characteristics of home scanners and the side effects of image compression and storage methods, the reticles appear larger in digital versions of the photos than they do on the prints or negatives.

The flag example above is particularly compelling. The fiducial is easily visible over the red (correctly exposed) stripes, but disappears against the white (saturated) stripe. The conspiracists would have us believe that the white stripes were somehow (and for some unknown reason) pasted into the photo over the top of the fiducial.

The conspiracists must also deal with the idea that someone falsifying a photograph could easily redraw the fiducial over the top of pasted-on material, completing the fiducial and increasing the credibility of the photo. This would require only a few seconds with each photograph. They also have to explain why the fiducials were added to the background before the alleged doctoring was done.

The smart way to falsify a reseau grid would be compose the photo on the light table without the reseau grid and then apply the reseau grid as a final step once everything else was complete. Applying it first to the background would not save time or be any easier, but it would cause lots of problems if you then wanted to doctor the photo. Again, this is ad hoc reasoning and why many conspiracists have to rely on the Whistle-Blower Theory to explain what they claim shouldn't be there.