Moon landing: artificial generation of parallel beams of light In this video of Adam ruins everything, Adam tries to debunk the claim that moon landing was fake using a central argument that we couldn't produce parallel beam of white light to mimic sunlight with computer graphics or lasers.
But can't we easily produce parallel beam of light using a parabolic mirror and placing the light source at the focal point?
Am I missing something? or  Are the makers of this video and a scientist who features in the video is unaware of this?
Note: I'm not arguing about moon landing being fake, I'm only arguing that this particular argument of parallel light beams is invalid.
 A: Tl/Dr: Adam's handling is certainly incomplete, but there are interesting threads to tug on which were not covered in the video -- particularly in dealing with just how massive such a light source must be.
This is an interesting one.  I don't think Adam and his guest covered everything about the forensics.  If you had a parabolic mirror the size of the set, you could indeed generate parallel light across the entire scene simply by putting a light source at the focus.  But how large does it have to be?
The moon landing footage also demonstrates the expected parallax.  Things in the background move slower than the things in the foreground, and at an expected rate.  This gives strong indications as to the size of the set needed.  A mat painting behind the actors would not generate the expected parallax (you can see this in old movies if the camera moves in any scene with a mat).
Which means the set has to be pretty honking big.  It has to be a pretty big parabolic reflector.
So where's the focus?  We can put the light source really close (making a really strongly curved parabolic shape), or really far (making it more and more like a plain ol' sun).  The sound stage can be smaller if you can put it really close.  But there's a catch.  Parabolic reflectors do not light a scene evenly.  They light the centers much stronger.  The light source emits light evenly in all directions (spherically), but the parts of the mirror on the edge see less of that light.  They are at a very oblique angle.  You can observe this effect on your own with plain ol' sunlight and a flat surface (like a can lid).  As you rotate the surface, you'll see it reflects more light when it is oriented such that the sunlight hits it dead on, and reflects almost no light when its lit on-edge (you'll get some lighting from the sky or from the ceiling, if you do it indoors).
This means that there would be a very obvious uneven lighting.  This would have to be addressed with a very special gel on the front of the light, which dims the light in the middle.
At this point I must admit that I have not done the equations, so I cannot prove that the lighting theory here is debunked.  But I do point out that the closer the light is (shorter focal length on the parabolic mirror), the more raw light intensity is needed to sufficiently light the edges.  This means you need a very bright light.  The shorter the focal length, the worse the issue will be.
Go grab a flashlight with a standard parabolic reflector (one that can focus the light into a decently small spot).  Look at the light pattern.  Imagine lighting the entire scene with only the dimmest fringe of the light, perhaps by printing out a clever pattern on transparency paper and putting it in front of the light.
Now research just how bright studio lights had to be around 1970 to get a good picture quality.  Think about how bright that light has to be.
It's not a complete debunking, but it is a direction you can take to analyze just what an astonishing lighting system it would have to be.  Issues like cooling start to become complicated.  You certainly couldn't make a gel, as lighting technicians think of it today.  It'd burn to a crisp.  You'd probably have to make it out of metal, and its fun to think about the technical challenge of making nice smooth gradients using holes in metal.
You can also compare the brightness required to the beam that is currently considered the brightest light on the Earth: the skybeam on the Luxor.  See how that compares to the lighting requirements for this set, and ask whether something that bright could be built in the 1970 timeframe (Xenon arc lamps have undergone continual improvement).  Remember that the skybeam is solidly situated on an unmoving platform, while this "sunlight" would have to move from shot to shot.
Modern recommendations are on the order of 3000 lumens per 100 square feet of stage.  The Luxor skybeam is 13650000 lumens, so it could light 455,000 square feet.  For scale, a Manhattan city block is about half of that.  However, those calculations are done without accounting for any adjustment of intensity that is needed to get the light even.  If you lose 90% of your light in this way, suddenly you're only covering 45,000 square feet.  Now we're talking about lighting a football field -- and using a mobile-mounted Luxor skybeam to do it!  And even worse, those were modern lighting recommendations.  Professional 1970's cameras were extremely weak compared to the cameras available to the modern home videographer.
You can resolve some of these issues by using a light with a longer focus, but now you're increasing the size requirements of your set.  Now we have to start questioning where such a building could have been made.  Certainly not Hollywood.  It would have to be elsewhere, which opens up a whole different thread of conspiracy.  Remember that the lighting needs to be able to come from any direction the "sunlight" could have come from.  It'd be a big building.  Yes, we made Los Alamos in secret... but its up to you to decide if this is the same thing, warranting the same level of secrecy.
So I think you're right, that Adam fails to properly debunk this myth.  However, it is less clear that his guest, a forensic analyst, has failed to debunk the myth.  There are several directions that could have been taken, they simply were not addressed in the 5 minute video.  I suppose we could email him and ask him for more details.
