Double shadow effect in Apollo 11 photos

[Rob48]

I was just browsing some of the Apollo 11 pictures on the Project Apollo Archive on Flickr and noticed an odd effect in some of the photos taken from inside the LM shortly after the EVA. The shadow of the LM appears "doubled", with an inner dark shadow and an outer less dark one.

The effect is not symmetrical - for instance on AS11-37-5462 the inner shadow is displaced to the left of the centre of the outer one:

AS11-37-5462 by Project Apollo Archive, on Flickr


And on -5463 it is to the right:

AS11-37-5463 by Project Apollo Archive, on Flickr

Any ideas what causes this?

[smartcooky]

Diffraction?

http://www.exploratorium.edu/snacks/diffraction

https://en.wikipedia.org/wiki/Diffraction

[Glom]

I would imagine it's a window reflection thing.

[onebigmonkey]

I found a similar thing with Apollo 12 images, and never really got to the bottom of it.

[Allan F]

Probably reflections inside the double layers of glass in the window.

[Zakalwe]

Penumbra and umbra I would have thought. The Sun is not a point source of light and its rays are at f110. The shadow cast by the sun will have a slightly lighter area (the penumbra) and then an area of total obstruction of the light (the umbra).

[Rob48]

Penumbra and umbra I would have thought. The Sun is not a point source of light and its rays are at f110. The shadow cast by the sun will have a slightly lighter area (the penumbra) and then an area of total obstruction of the light (the umbra).

I did wonder about this but I am doubtful for a couple of reasons. First of all it seems too sharply defined: even without the blurring effect of an atmosphere I can't imagine it would make such a sharp line. Secondly of it was a penumbra I would expect to see it in many more photos, not just these ones.

Actually a third: the relative positions of the "inner" and "outer" shadows seems to alter depending on the location within the frame.

I suppose it must be a window reflection effect but I can't figure out exactly how it happens.

[Glom]

I think it's internal reflections in the window. Penumbra is the softening around the edges of the shadows.

[Mag40]

These 3 Apollo 14 ones are the most dramatic:
http://history.nasa.gov/alsj/a14/AS14-65-9211HR.jpg
http://history.nasa.gov/alsj/a14/AS14-65-9212HR.jpg
http://history.nasa.gov/alsj/a14/AS14-65-9213HR.jpg

If you flick between 9212 and 9213 you can see they are shot from the same window with the camera tilt changing. The interesting bit is that the lighter area also changes, even though the shot was taken at the same time.

So, it isn't an external effect and is either a camera anomaly or a window anomaly. I'll leave that one to the experts to decide upon.

[ka9q]

Definitely multiple internal reflections in the window.

[bknight]

Definitely multiple internal reflections in the window.

Its this type of effect that drives the hoaxers into a frenzy, frothing at the mouth discovering the "holy grail" of multiple images.

[Glom]

Definitely multiple internal reflections in the window.

Its this type of effect that drives the hoaxers into a frenzy, frothing at the mouth discovering the "holy grail" of multiple images.

Without having any coherent way of explaining why hoax would explain it.