Author Topic: Double LM Shadows.  (Read 680 times)

Offline Combat Wombat

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Double LM Shadows.
« on: August 25, 2019, 08:22:10 PM »
Greetings all, my first post, hope it's in the right section, admin please move if needed. I'm looking at the Apollo Lunar surface photos and noticed this https://www.flickr.com/photos/projectapolloarchive/albums/72157659051610141/with/21496703049/
Double LM shadows, I've seen them on all missions (except XIII of course) and these are the most prominent examples. Only seems to happen when in the LM cabin and affects the LM shadows and nothing else in the picture, man made or natural. They seem extremely mobile too, moving between shots. How does this happen? Thanks

Offline AtomicDog

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Re: Double LM Shadows.
« Reply #1 on: August 25, 2019, 09:10:32 PM »
Greetings all, my first post, hope it's in the right section, admin please move if needed. I'm looking at the Apollo Lunar surface photos and noticed this https://www.flickr.com/photos/projectapolloarchive/albums/72157659051610141/with/21496703049/
Double LM shadows, I've seen them on all missions (except XIII of course) and these are the most prominent examples. Only seems to happen when in the LM cabin and affects the LM shadows and nothing else in the picture, man made or natural. They seem extremely mobile too, moving between shots. How does this happen? Thanks

The fact that it is happening only in the LM is a clue: the LM window is double paned - you are getting double reflections of the shadow.
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Offline onebigmonkey

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Re: Double LM Shadows.
« Reply #2 on: August 26, 2019, 01:54:17 PM »
I asked this question some time ago. I can't remember the outcome but your post made me look at it again.

I don't recall seeing it in other missions, but it's very noticable on Apollo 14. Here's an example of part of an image from the magazine you link to, conpared with one taken at a different time that doesn't show the feature (AS14-66-9320):



I've adjusted the contrast on the mag 66 one but not the other.

What you can see is that not only is there a reflection of the LM shadow, but also some of the shadows of the small craters around it, offset to the same kind of degree as the shadow.

Offline Combat Wombat

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Re: Double LM Shadows.
« Reply #3 on: September 01, 2019, 09:37:58 PM »
Hi, thanks for your feedback, sorry about the delay, been busy. Indeed the LM windows are double paned but don't you only see the double reflection effect from objects on the observation side? I've experienced dual sheet glass on many occasions, on buildings, marine vessels and aircraft but I've never seen anything like this. I've only ever seen clear, strong dual reflections from objects on my side of the glass, never from objects on the far side. If the LM windows possessed such properties then wouldn't that count as a serious design flaw? Imagine landing the thing cross-eyed! The other curious thing here is that it's only the LM shadow and some craters that are doubled, wouldn't the horizon, the many rocks and their shadows be duplicated also? Take a look at this DAC footage taken from Aldrin's (Armstrong's too, briefly) window post EVA, you can clearly see a double shadowed LM. At 0:31 the paler section is on the right by a noticeable margin, the camera pans to the right and rests on the flag then pans left and the paler LM shadow has moved to the left. At 0:41 there's a cut and the LM shadow has no obvious pale sections but at no time do I see any duplication of the thrusters, the horizon, the flag or the rocks below the flag for the duration of the footage in either window. The F stop appears to have been changed during the 0:41 break allowing more natural colours and a less bleached effect. The footage runs for some time, covers many angles through both windows but the double image effect only appears on the LM shadow. Thanks



Offline AtomicDog

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Re: Double LM Shadows.
« Reply #4 on: September 01, 2019, 09:48:13 PM »
There's a double Earth at 1:49 in the video, during orbital earthrise. It's obviously an effect that happened at certain camera and lighting angles, and something that the astronauts quickly got used to.

There are other double reflections in the video during the rendezvous with the CSM, reflecting images from the inside of the cabin. Frankly, I don't see what's supposed to be so unusual.
« Last Edit: September 01, 2019, 09:55:10 PM by AtomicDog »
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Offline Zakalwe

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Re: Double LM Shadows.
« Reply #5 on: September 02, 2019, 02:15:02 AM »
I've never seen anything like this.

Probably because you've never been in a LM, on the surface of an airless world? ;)
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Offline Abaddon

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Re: Double LM Shadows.
« Reply #6 on: September 02, 2019, 07:31:19 AM »
I've never seen anything like this.

So what? Just because you have never seen it means it can't possibly be real?  Have you personally ever seen an electron? Are they not real?

And for the record, it is a trivial effect seen in double or triple glazed windows. And I have seen in many times. So what use is your incredulity to anyone, even you?

Offline Kiwi

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Re: Double LM Shadows.
« Reply #7 on: September 02, 2019, 09:06:42 AM »
There's a double Earth at 1:49 in the video, during orbital earthrise. It's obviously an effect that happened at certain camera and lighting angles...

The clue is in the double Earth in the black sky below the actual Earth, along with the 0:41 view of the LM shadow with no doubling.

It's impossible to project darkness into a lit area, but we can project light into a dark area, so in the first view of the "doubled" shadow, we're actually seeing a portion of the lit ground superimposed over the dark area. Considering the large difference in brightness, it's no surprise to me that at certain angles the multi-paned window did a little reflecting. Furthermore, it might even be an in-camera effect only and not visible to the naked eye. Multi-coating of lenses to cut down internal reflections was in its infancy during the Apollo missions, and computerised design of lenses hadn't yet been invented.

Back in the 1970s when I first had my own professional darkroom there was a sign on the studio wall next to the darkroom door: "Shut the door or the dark will leak out." And to some visitors' surprise, the interior of the darkroom was painted white.
« Last Edit: September 02, 2019, 09:19:38 AM by Kiwi »
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Offline gillianren

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Re: Double LM Shadows.
« Reply #8 on: September 02, 2019, 10:10:19 AM »
I see a double Moon through my double-glazed windows all the time.
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Offline bknight

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Re: Double LM Shadows.
« Reply #9 on: September 02, 2019, 10:56:26 AM »
I've never seen anything like this.

So what? Just because you have never seen it means it can't possibly be real?  Have you personally ever seen an electron? Are they not real?

And for the record, it is a trivial effect seen in double or triple glazed windows. And I have seen in many times. So what use is your incredulity to anyone, even you?

Indeed, If I can't/don't understand something it must be fake.  And of course If I can't figure something out, then it must be fake.  Two logical fallacies one of which Combat Wombat displays.
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Offline AtomicDog

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Re: Double LM Shadows.
« Reply #10 on: September 02, 2019, 12:35:53 PM »
Looking at the CSM approach again, there is a clear double reflection off of the metal foil of the CM. As the CSM rolls, you can clearly see the reflection move to match the orientation of the primary highlight. Indeed, just before the clip ends, you can see another, fainter reflection in the same orientation, joining the first.
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Offline Jason Thompson

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Re: Double LM Shadows.
« Reply #11 on: September 02, 2019, 03:10:27 PM »
Hi, thanks for your feedback, sorry about the delay, been busy. Indeed the LM windows are double paned but don't you only see the double reflection effect from objects on the observation side?

No. It depends primarily on the relative angles and the strength of illumination. You'll see the effect with whichever is the brighter. I've seen a double moon out of a double glazed window on many occasions, for example.

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If the LM windows possessed such properties then wouldn't that count as a serious design flaw?

No, it's a natural property of the material the window is made of. All glass panes do it to some degree. That's basic optics.

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Imagine landing the thing cross-eyed!

Why would this effect be even close to 'landing cross-eyed'? Even with the double image you can still tell which is the 'real' and which the reflection.

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The other curious thing here is that it's only the LM shadow and some craters that are doubled, wouldn't the horizon, the many rocks and their shadows be duplicated also?

Not necessarily. Given the relative wide angle of the camera lens I wouldn't expect the see the entire image duplicated in that way, just certain part of it depending on the relative angles of the optical axis and the window.

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The footage runs for some time, covers many angles through both windows but the double image effect only appears on the LM shadow.

So what do you think is more likely? That you have not fully grasped the optical effects in the imagery, or that somehow this common occurrence is proof of something dodgy and no-one picked it up before publishing the images and footage over the course of a bunch of missions covering a few years until you came along half a century later?
« Last Edit: September 02, 2019, 03:20:48 PM by Jason Thompson »
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Offline smartcooky

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Re: Double LM Shadows.
« Reply #12 on: September 03, 2019, 03:44:01 AM »
Another thing to consider (if it hasn't already been mentioned) is, were the cameras fitted with polarizing filters or even ND or UV filters? If they were, then that could go some part of the way to explaining differing reflection levels in different parts of the image.
« Last Edit: September 03, 2019, 04:16:43 AM by smartcooky »
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