Hasselblad Réseau Plate

[q.g._de_bakker]

So let's cut this short and decide here and now it's all evidence that it all was a hoax played on all of us...

 

If you cannot understand how reflections work, how can you point out anomalies that require our special attention?

Is this part of the PNet redesign? Becoming a platform for nonsense, just like facebook, instagram, twitter and what have you?

[rodeo_joe1]

Ah, but I do understand how reflections work, which makes no sense of previous 'explanations'.

OK explain this: In order to be of any use as a measurement tool, the fiducial marks need to be in intimate contact with the film. I.E. the engraved side of the glass plate is toward the film. Therefore the fiducial crosses are only illuminated by the semi-diffuse light reflected from the film surface surrounding them. Not directly back-lit by an image of the sun. It follows that a plane-parallel reflection from the front (lens-facing) surface of the reseau plate cannot be properly focused back onto the film. It also follows that in the unlikely event of reflection from the rear of the lens sharply focussing those fiducial shadows, then the rest of the film image would also be sharply reflected and double-imaged. Which is obviously not the case. Otherwise there would be a double and distorted image of the whole scene.

So, if the reseau plate was not accidentally fitted the wrong way round (stranger things have happened) the conclusion might be drawn that the - overly sharp - ghost fiducials have been added after the fact; but for what purpose?

A prank?

To fire a conspiracy theory?

To create a false mystery?

Or, if they are a genuine phenomenon. How?

And simply dismissing the above analysis as 'nonsense' is no response at all, and simply shows a total lack of understanding of how a reseau plate works on the part of the respondent.

Edited October 27, 2022 by rodeo_joe1

[Wobbegong]

On 10/26/2022 at 9:02 PM, q.g._de_bakker said:

So let's cut this short and decide here and now it's all evidence that it all was a hoax played on all of us...

If you cannot understand how reflections work, how can you point out anomalies that require our special attention?

Is this part of the PNet redesign? Becoming a platform for nonsense, just like facebook, instagram, twitter and what have you?

 

But don't you think they would've rectified the reflection problem after Apollo 12? It occurs right up to Apollo 17.

Apologies, didn't mean to rock the boat but I've been looking at the archive for a few years and I'm at a loss to explain how some of the images came to be. For example this sequence from the Flickr archive. There's no duplicated fiducials and the first image the borders are clear and crisp, the middle, the frame, except for the right hand side is extremely distorted and the sun bleeds over the borders. The anti-static electrodes are elongated and distorted and in the last image it returns more or less to normal and continues so for the remainder of the magazine. This effect seems confined to sun up or near sun images and if you look at the center image scanned off the original film roll you'll see the light bleeds all the way to the sprocket holes on the right. On the left there appears to be the edge and top corner of a faintly duplicated transparency bisecting the sprocket holes. 

What caused this? The harsh lunar conditions or sloppy lab/duplication work? 

[q.g._de_bakker]

1 hour ago, Wobbegong said:

 

But don't you think they would've rectified the reflection problem after Apollo 12? It occurs right up to Apollo 17.

Apologies, didn't mean to rock the boat but I've been looking at the archive for a few years and I'm at a loss to explain how some of the images came to be. For example this sequence from the Flickr archive. There's no duplicated fiducials and the first image the borders are clear and crisp, the middle, the frame, except for the right hand side is extremely distorted and the sun bleeds over the borders. The anti-static electrodes are elongated and distorted and in the last image it returns more or less to normal and continues so for the remainder of the magazine. This effect seems confined to sun up or near sun images and if you look at the center image scanned off the original film roll you'll see the light bleeds all the way to the sprocket holes on the right. On the left there appears to be the edge and top corner of a faintly duplicated transparency bisecting the sprocket holes. 

What caused this? The harsh lunar conditions or sloppy lab/duplication work? 

The obvious, and quite simple answer is that this is caused by internal reflections. And that there is no more, no mystery to it.

Yes, reflections are the result of light following some quite intricate paths, especially when curved surfaces are involved. And the internal surfaces of lens housing, camera and magazine.

And yes, reflections are more obvious when light is of high intensity (such as direct sunlight, with no attenuating atmosphere). And there is that light piping in both reseau plate and film too, to make things even worse.

Would they not have rectified the problem, you ask. No. Other than perhaps asking astronauts not to shoot directly into the sun. What would you suggest they would do?

Edited October 28, 2022 by q.g._de_bakker

[Wobbegong]

18 hours ago, q.g._de_bakker said:

The obvious, and quite simple answer is that this is caused by internal reflections. And that there is no more, no mystery to it.

Yes, reflections are the result of light following some quite intricate paths, especially when curved surfaces are involved. And the internal surfaces of lens housing, camera and magazine.

And yes, reflections are more obvious when light is of high intensity (such as direct sunlight, with no attenuating atmosphere). And there is that light piping in both reseau plate and film too, to make things even worse.

Would they not have rectified the problem, you ask. No. Other than perhaps asking astronauts not to shoot directly into the sun. What would you suggest they would do?

Thanks for your input, I'm surprised Hasselblad didn't rectify the problem. Surely they would've been aware during testing of the cameras and lenses and their reputation was at stake.

I've been looking at many lens flares and they are rather inconsistent, fiducials closest to the sun or flare can be barely affected but others further away are D&D like AS12-46-6729, shown here singly and in context with the preceding 2 images. There's no strong flares in the first 2 but then there's this strange vertically cut lens flare that begins a few mm from the edge of the transparency. Three fiducials are duplicated, except for the one closest to the flare.

Then there's AS14-67-9368  where we have one wildly D&D fiducial, the other one is perfect. The antistatic electrode appears duplicated, flipped and smudged. The lens flare which surrounds the sun in so many other images appears to be neatly cut horizontally and only surrounds the bottom third!

I've wrote to NASA and Hasselblad some time ago regarding this, no answer despite there being literally 100s of images like this.

[q.g._de_bakker]

31 minutes ago, Wobbegong said:

Thanks for your input, I'm surprised Hasselblad didn't rectify the problem. Surely they would've been aware during testing of the cameras and lenses and their reputation was at stake.

I've been looking at many lens flares and they are rather inconsistent, fiducials closest to the sun or flare can be barely affected but others further away are D&D like AS12-46-6729, shown here singly and in context with the preceding 2 images. There's no strong flares in the first 2 but then there's this strange vertically cut lens flare that begins a few mm from the edge of the transparency. Three fiducials are duplicated, except for the one closest to the flare.

Then there's AS14-67-9368  where we have one wildly D&D fiducial, the other one is perfect. The antistatic electrode appears duplicated, flipped and smudged. The lens flare which surrounds the sun in so many other images appears to be neatly cut horizontally and only surrounds the bottom third!

I've wrote to NASA and Hasselblad some time ago regarding this, no answer despite there being literally 100s of images like this.

There really is not much to say. Not by NASA, nor Hasselblad, nor anybody else. This is what a strong light in the field of view does. It's flare. There is no more to it.

[tom_chow]

I think you'll get more answers at space forum: https://space.stackexchange.com/questions/60741/duplicated-and-distorted-fiducials

I was going to suggest raytracing the patterns back, but someone there has already suggested it. However, to do it properly, you'd need to do it in 3D - the Réseau plate is 4mm thick, the rear of the lens is ~20mm from the plate, the back focus is 61.6mm,  and the lens looks like this:

 

Here is the optical arrangement with the Réseau plate (which is part of the optical design)

 

Note that all planar raytraces from the center and corners of the fiducials go back to where the sun is located. The curvy fiducials only show up in the glare (as in the picture you showed above with the 1/2 cresent glare) so it's probably part of the glare projection. Also, those negatives appear to be very under exposed with clipped highlights, so the glare (and it's pattern) can be recorded on the direct image.

It's probably easier to pick up that lens and just test it. Just not easy to "pick up"...

 

 

 

 

 

[BernardMiller]

I really don't think there's any mystery to all of this--it sounds like some folks are getting borderline "The Moon landing was a hoax!" on us, which is just silly. (Why am I sure we went to the Moon? Because, basically--it's *easy*. I mean, it does cost a butt ton of money for the hardware, and to make sure it works well enough that the folks we sent up there make it back safely and don't die. But it's only 240,000 miles away, hell that's far less than a pubic hair width in astronomical terms.)

When you get the Sun in or just outside of the frame, whether it's with an earthbound Hasselblad or a Moon 'Blad, you're gonna get: shadows from the film gate on the edge of the negs, multiple reflections (off both faces of the Réseau plate on the Moon, off the curved surface of at least the rear lens element front surface and possibly other lens element surfaces, and possibly from internal camera structures), flare & ghosts, etc. And if you're getting specular reflections off metallic surfaces on the LEM or elsewhere, *they're* going to cause weird flares and other effects.

Not only that, you're gonna get something else within the film that nobody's mentioned explicitly above (although someone has noticed the effects): halation. NASA did work with Kodak to design a film which reduced that as much as feasible--but when you're getting sunlight that's totally unfiltered by any kind of atmosphere coming straight into your lens, there's no way you're gonna be able to mitigate that much at all appreciably, let alone eliminating it entirely.

So I believe that some people are at risk of going down weird rabbit holes, and staring too long at inconsequential things to the point their brains start convincing them--as they are so good at doing--that they're seeing some sort of pattern that really isn't there...like Jesus on a potato chip or something.

Edited November 4, 2022 by BernardMiller

[Wobbegong]

Well, maybe they went to the moon but I'm not sure the photos were snapped there, either that or their lab technicians were stoned! I've been browsing the archive at Flickr and March To The Moon and finding a lot of artifacts like these duplicated and 'dancing' rocks within the shadows found in 2 images taken less than a minute apart on Apollo 12. There are literally hundreds of them, especially in Apollo 11. Often I'll find artifacts in MTTM taken from scans of the original images that have been photoshopped out in Flickr so it appears that someone is aware of the problem.