Trying to figure out if this shot (23:50) in 2001: A Space Odyssey is a camera movement or a zoom happening. I'm pretty sure it's a zoom but some confirmation would be helpful. For those that are wondering, I'm making a short video essay on Kubrick's zoom technique, and would love to be able to take an example from 2001.
It turns out this was an incorrect interpretation - see other answers below - it was based on a principle of no-parallax [perspective shift], but was actually achieved in another way, which also, incidentally, has no parallax.
As [we are fairly sure] we know, Kubrick used spherical lenses not anamorphics on 2001, we can use a simple perspective test to see if it was a zoom or camera move.
If you move the camera, perspective will change. If you zoom, it will not. [This is physics 101.] This is harder to test on anamorphic lenses as they also change image framing as you pull zoom in quite a complex way - so let's be glad we don't have to compensate for that too.
By the simple expedient of taking an early and late frame & re-sizing one to fit over the other, you can tell this is entirely a zoom.
I have intentionally stepped this out by 20px vertically so you can see it. Accurately lined up, there is no discernible perspective change at all & therefore the overlay vanishes entirely.
Because of the difficulty in hand-matching the compositing for the 'windows' you would have to assume this was all done in post; so it was all shot at the widest and zoomed after compositing. Otherwise the compositing would have to be hand-matched for every frame. A nightmare of a task when everything was done by hand.
I can also find no reference to Kubrick using zoom lenses before Barry Lyndon, which would add weight to this argument.
 This confuses photographers too, especially when using crop-frame cameras, so I did a beginner's guide on PhotographySE - How does crop factor affect perspective? - if you want to see this in practice.
Its not a zoom. Its a motorised (selsyn) track back on a huge 8x4 ft print of a large format probably 5/4 still of the model interior of Space Station 5 stuck on glass and shot pretty much the way matte-paintings were done back then, with the windows and bay entrance cut out, with black velvet beyond. Multiple repeat passes were done to add in all the rear-projection elements of people in the windows. The flares at the beginning come from the lights backlighting the white lit strips around the bay, a happy accident. The approaching Orion and rotating stars are matted in after.. Im afraid I have no hard evidence of the approach I described other than I knew a few people who worked on the FX in 2001. When I started in the business I worked at a place called the Magic Camera company in Shepperton studios which had all of Wally Veevers giant matte glasses and tech gear that was used to move the 65mm FX cameras on that movie. I was fortunate to work alongside a cameraman called John Grant who was one of Wally's assistants and was a fountain of info on their work on 2001. He described in great detail how a lot of the photos of the craft and landscapes were filmed on these big glasses, the biggest being 15ft by 10 and weighed a ton! There was also a massive worm gear which I believed was used to film the slit-scan. Brian Johnson who is still around and a senior fx technician on 2001 and is also a good source for undocumented info on the movie. I edited my original comment as it wont let me add a new one, saying its too long.. Steve
I'm not submitting this as an answer, just an addition, as I realize a lot of the interesting chat is in comments, that might one day get lost.
This video features interviews and quotes from both Douglas Trumbull and Brian Johnson, both of whom worked on 2001.
Unfortunately, the interview links with the video are now dead.
And this whole technique of mounting 2-dimentional flat photographs of the models on a giant sheet of glass and then being able to project little movies into the windows. You’ll see a lot of shots in 2001 where there’s really not any perspective shifts going on because it’s a 2-dimensional photograph. And we had to mount it on glass to superimpose one thing against another.”
“So we would go to the storyboards and take the shot that we were doing on any particular day and then I would set it up on the blacked-out sound stage. The electrician would come in and set up the lights [where] Stanley wanted them. Stanley would set the key light were he wanted it, then we would blanket the exposure. We had problems with processing the film because we at times would work with a f/stop of 128 for about 10 minutes -- which was basically an aperture the size of a pinhole -- this was because we had to get a certain depth of field, but also everything had to always be in focus as well.
From there, I had to clean the negatives that Stanley had shot. Then Stanley would go over those to determine which part of the image he wanted to appear on the screen. Once he had decided, he would have someone cut out the model from the composite made from the negative with a surgical scalpel and then that would be placed onto the glass plates.
Once the glass plates were made, they would re-photograph those with a film camera. [The] cameras would track along with the image or move in on it as was necessary. We didn't very often shoot the models with a film camera, but we shot more with a still camera really.
It was animation. It was important to do it this way because then we could then go back and re-re-photograph those with background projections in place.
(Brian Johnson Interview) “I was given the job of getting all of the models ready to do the still photography with Stanley. We had an Electrician, myself and Stanley on a completely blacked-out sound stage.
Stanley would work for hours lighting the models and then he would shoot the 4"x 5" plates, and those plates would then be used to make enlargements for the animation. We used Polaroid Land 300 stock. It was the same stock that spy planes used, and it was very fine grain black and white. It was very high process stock, it was fantastic stuff”
Some of this is from:
The Making of 2001: A Space Odyssey: A Space Odyssey
same or similar quotes here:
Just to add:
Brian Johnson (Nov 2023):
"There were a number of high res/fine grain photos stuck on glass with rubber cement. We used Polaroid Land ultra fine grain negative sheets and Ken Bray made the prints. Most wound up on Wally Veevers ‘sausage factory’ rig"
edit: Wow, HAL popped up and asked if i was a bot! :P