How a Film Projector Works
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- čas přidán 15. 06. 2024
- Bill tears apart a film projector to reveal the amazing mechanisms used in the pre-digital age to trick the mind into seeing a moving image. He uses high speed photography and animations to show how the projector moves the film intermittently, how a shutter strategically blocks light as the film moves, and how the photo sensor reads the sound. He explains how all these mechanisms are synced.
You can become an advanced viewer of engineerguy videos by signing up at www.engineerguy.com/preview. - Věda a technologie
Dude could literally talk about rocks and I'd be interested
HAHA i know right!
Totally
what if it's about a rock crusher
Don't let him man! You would feel your life worthless after knowing stone from him that well!!!
Youre absolutely right
This is the best explanation I've seen of this process, which I could never quite understand for years.
I know, I'm mind blown.
It all makes sense now
Ahh! That 26-frame sound-offset is why, when you're watching a piece of film that has broken and been repaired, you see the skip, then you hear it about 1 second later. I never knew that. Very cool!
Great video! So well explained and very engaging, please do more! Love learning about how things work :-)
xisumavoid A wild Xisuma appears!
xisumavoid Thanks ... more on mechanisms in the works right now ...
xisumavoid Never expected to see you here :'D
Xisumavoid, everyone I watch, you do too...except I watch you too!
I was watching you play hermitcraft, then I looked up how a projector works for a design I'm doing, and I see you here. Wow.
I love your outro "I'm Bill Hammock, the engineer guy." It's just feels so satisfy for some reason. I need a shirt with that on it
you are not bill hammack though
Maybe he is Bill Hammack and that is his decoy account that he uses to compliment himself anonymously.
lol
@@weenisw r/asablackman has stuff like that
This goes to show that although generations before us were less advanced, they were by no means less intelligent or innovative.
AlphaOmega It was only 1979 dude...
Burgled Projector technology dates back way, way further than this particular (1979) model..
AlphaOmega ok?
Burgled What yo
+AlphaOmega
Today we have more and we can see more because we are standing on the shoulder of giants.
Ah, yes. I remember those. Before computers were so easy to obtain in schools, tech-obsessed kids like me had to settle for things like "the audio visual club". The 16mm projector was often the most complicated equipment that we could get our hands on (that the teachers allowed us to touch). Still, one could learn a lot from them. A mistake that was particularly easy to make was in wrapping the film around the sound drum. If you wrapped it loosely, everything seemed to work OK except that the sound was jittery and distorted. You had to make sure that the film was snug around the drum in order to get the best sound quality. All this might sound irrelevant to modern tech, but that little sound-drum hazard taught me a lot about how to deal with urgent problems. In the 6th grade, our club was responsible for threading a film that would be shown at a big school meeting. When the sound was distorted, it felt like a crisis to us. Half the school is waiting on us! The teachers had no idea how to help, so it was up to us. Now what? Learning how to calm down as a group and debug the problem quickly was a big event for us. Low-tech or not, it helped me develop social and mental skills that I still use today as a computer programmer.
I did this in school also then did it for the U.S.A.F.
Yes, it seems if the film is loose around the sound drum, the slit will be incorrect and variable distances away from the film, thus sometimes making the sensor detect too little light and lowering the volume, sometimes making it detect an average from a wide length of film, causing aliasing and other artifacts in the frequencies
@@luigivercotti6410 The slit of light is focused onto the edge of the drum, so if the film is loose, it is out of focus. This is the main cause of the distortion.
Poor quality sound can also be caused if during cleaning the lens is not correctly focused, or the slit is not set to exactly 90 degrees to the film.
Soundtrack test films are needed to set everything correctly.
In major cinemas, tests and fine adjustments are carried out daily. With a stereo track their are 2 side by side images, so the adjustment is very critical.
Bill! What an amazing breakdown of the movie projector!!! We absolutely love this!
That little ingenious engineering solution in the takeup loop has some interesting history as well - called the Latham Loop, it was the key to preventing Edison's Motion Pictures Patent Company from monopolizing camera and projectors in the early years of cinema.
Well done. The animations clarified where words alone would only have confused.
BILL. Please engineer a way to make multiple copies of yourself so that there can be a new engineerguy video every week. My life will be a struggle until you successfully explain the mechanics behind everything around me.
>tfw you will never be as alpha as engineerguy
He's a real hero
Real human bean
nise meem arrows m8
tfw u will never meme as hard as this guy
louis romero you killed me with that bean
>tfw not all heroes wear capes
Great video. Interesting to think that one single axle keeps the entire projector going.
Ian Gacek The single axle design makes the whole thing very impressive.
Ian Gacek Agreed! It to me about four hours to rip apart the projector (it's built like a tank) to get to the main internal mechanisms. I really had no idea how it worked until I saw for myself.
Ian Gacek
While the Bell and Howell projector here uses a worm screw where most projectors use belts, that component is actually the Achilles heel of the machine. The original worm screws have a tendency to crack, which completely screws up the projector's timing and can lock up it up, and require a complete disassembly of the projector to replace. They then have to be adjusted to ensure they work properly. Good news is the newer worm gears are made of a material that doesn't crack anywhere near as easily.
@@Videogamehistorian00 Traditional cinema projectors have a high precision gearbox that includes oil pumps. Many of these machines ran 12 hours a day for more than 30 years without gear replacement.
Clear and interesting explanation. I was an "AV Boy" in grammar school for three years in the 1960s, and threaded 16mm projectors hundreds of times, but never knew the details of the underlying technology until now.
Very educational! It is pretty eye opening to really see how every little bit works in sync inside an old camera. Thank you for this!
yo icton do you like mac and cheese?
wtf were you doing here 6 years ago Djy, all this won't help you make better gmod vids
Not once did I think I'd be interested in how a film projector worked, and here I sit in my chair, utterly corrected. Great video!
I had no idea the flicker rate was multiple times the frame rate of the film :O That's incredible! For years I knew how projectors worked, but this little detail is brand new to me, and so amazing for it! :D
Thank you for the upload!
And thank you, Chris Boden, for sending me here :P
In the silent days, films ran at 16fps. This is why when we see these films today, everything looks speeded up.
In the cinema. a maltese cross drives a sprocket for pull down on 35mm film. this mechanism shows every frame twice at a flicker rate of 48.
One of my new favorite channels started with a video about soda cans appear in my suggested feed
I love this guy. Subscribed two days ago and I've already learned more than I did in a year of school.
Goes to show how powerful CZcams can be as an educational tool
I am blown away by the ingenuity required to solve so many separate problems - flicker, film advancement, continuous sound reading - with such astonishing interlocking gears and components all working in harmony. The degree of timing and precision... I am left agape at what such a device represents.
I have taken film projectors for granted in my life - no more. This is a wonderment of a device.
Thank you for explaining it to me.
This was beautiful, thank you.
I worked with large cinema projectors and little tiny home ones. They are a fascinating piece of tech and history.
Also, The Take-up reel shaft is driven at a constant speed from the single motor through a belt system, but a slip clutch built into the take-up mechanism allows the take-up reel to change speeds as the diameter of film changes on the reel. This also serves to keep a small tension on the film so it takes up snugly. There are similar mechanisms on 35/70mm theater projectors. Some small projectors and usually theater projectors, also have an adjustable, low tension, slip clutch/brake on the supply reel mechanism to keep it from freewheeling as the film is pulled of of it.
I was wondering how this worked. Thank you.
I love the marveling feeling your videos leave me with. Peoples ingenuity is amazing and your ability to explain it in such a clear and nice way while expressing your own astonishment is so satisfying!
many thanks, i never thought that a film projector could be so interesting. The voice is also good to understand for me as a non english speaker
It is mind boggling that this was made 6 years ago and it stacks up so well to what is currently both "viable" and good quality on CZcams.
Amazing video
Another excellent video! I had no idea film projectors were this complicated, you explained it very well and the animations really helped with this.
Thank you!
If you think that is complicated, spend 15 minutes watching this video.
I spent 17 years running cinema films. LOL
czcams.com/video/Z8AXY-kq6UU/video.html
I love this! The mechanism of a projector is as exciting as a mechanical watch!
I think this is one of the very best series ever made. Keep 'em coming, Bill!
I remember this exact projector from elementary school in the 80's. Your videos are incredible. Thank you!
You are very, very good at what you do here. Thank you!
That was cool. Man! The guys that came up with these machines were brilliant. And expertly demonstrated and narrated. Thank you.
How your videos give me PURE JOY every single time I watch one is beyond me.
This is the best, most complete description of film projection (for non-film people) I have ever seen.
Great video, thank you...
Your videos are just so damn good, I cannot get over it!!
I was in AV club in high school in the early 70s. We had a full auditorium with a projection booth containing an RCA 16mm Porto-Arc sound projector. It had to be hand threaded and in its lamphouse was a carbon arc lamp that had to be struck by hand. Immediately after the strike the operator had to set the proper gap as seen via a tiny projected image of the arc through a prism onto an etched glass gauge. This took practice because it was easy to loose that arc right after successfully striking it. Once properly set clockwork fed the arc rods together at the rate that they burned away. The projector had its own vacuum tube audio amplifier that filled the auditorium with sound. The picture was vivid, this machine put on a great show! I loved showing films and got really good at it, becoming an “in demand” school assembly projectionist.
Man, Engineers and Physicists are the unsung heroes of our world, from the soles of your shoes, to the satellites in orbit, everything is Engineered to make our daily lives better, and more comfortable. The amazing thing is how affordable technology gets as time progresses. Truly, our owes much to these brilliant men.
Great animations in this one!
narnbrez Thank you!
This channel is awesome.
After watching your videos I have a much deeper appreciation for the complex mechanics of this (and other similar) devices. Many thanks, this is a new world for me.
Sometimes when I'm bored and youtube recommends it, I just watch an engineer guy video from the past because they're so good.
Excellent video -- I would love a rundown of how the intermittent sprocket works on a theatre style 35mm projector -- I used to run the machine but seeing it work was incredible. There is no shuttle to grab the film and advance it -- the bottom sprocket is is handled with some sort of planetary gearset where one of the gearsets is input from the drive, one is oscillating to interrupt/cancel the output and the last stage outputs to the film. This results in the sprocket being completely stationary, then suddenly jerking forward without hurting the film. I've seen a drawing in an ancient repair guide while I was working in the theatre but never actually got to see the gear mechanism.
frollard Reading further, wikipedia tells me its a geneva drive mechanism which just relies on intermittent drive of the output shaft by a thrust pin...
frollard Indeed the geneva mechanism was used in higher end cameras and projectors. Likely if we would have done a 35mm projector if we could have got hold of one!
***** Funny, in France we call that geneva cross a maltese cross.
***** it might be worth asking around. I suspect many MANY cinemas have them redundant now it's all gone digital
***** I think that IMAX still uses film. pretty huge film, too. 72 or above mm i think
Good one!
I love projectors and the way they give life to the little frames. The film motion is both real and an illusion at the same time in my opinion.
Great video and amazingly done!! My father has a 8mm projector and it's always amazing to see this machine working! What a piece of engineering!! And, by the way, it's also amazing to see how those films are robust. We have films of WWII and still intact!
side note for the youngins about film size and resolution. the chemical resolution of film and digital pixel resolution are not the same.
It is generally accepted that 4k resolution is about the same as Kodak 35mm print stock.
Production note: the shots with Bill next to the projector are a composite. We took a photo of the projector (before we took it apart) and added Bill on top of that. Here is the current state of the projector: i.imgur.com/1u7KBAo.jpg
I have to go to another App. I’m not.
BILL MILLER NO DOUBT, THAT MOBSTER STOLE FROM ME, I HAVE PROOF BUT COULD NEVER GET PROPER HELP TO PURSUE ANYTHING. JOHN FRANCIS BELFONTAIN DID NOT HELP ME & NEW ABOUT IT. MOBSTERS
you make me feel like a kid
watching you explain these concepts!!!
Great video Bill, with the added bonus of clear animation, and proper and exact explanation of how projectors work. Not too tech, and a joy to watch right to the last frame! -in super quality...
Regular engineering teachers: "This chart made in the 1940's shows how a modern projector works. If you have any trouble understanding, please ask me and i'll be sure to make fun of you because you don't understand"
Bill: "Let's take this apart and i'll show you how it works. "
Their is no 1940's chart for this one. It would take me days to explain it to you fully.
An engineer normally worked for 2 years before he was trusted to run a show.
czcams.com/video/Z8AXY-kq6UU/video.html
Steve has the best last name ever
Thanks!
Isn't your real name something else? Donald? No, Ronald McDonald, that's it. We used to call you Ronnie the Rat, right?
@@alephnull3404 CALL IT WHAT YOU WANT BUTS ITS CALLED MAJOR CORRUPTION & MAJOR GLOBAL PROPERTY THEFT & FRAUD
This is by far my favorite CZcams channel. Thank you for your excellent work!
I can't tell you how many of your videos I have watched. I've learned so many little things that I've thought of but have never researched and because of your easy to understand videos you have made family time less awkward. I can now keep the conversation. Thank you!
So the sound was not reproduced like using magnetic records (like cassettes) instead using and optic system ?
Claus Valca Row I know! I found that incredibly interesting.
Claus Valca Row I know! I found that incredibly interesting.
Claus Valca Row The first sound movies used records; one for each reel. Sound sync was a problem, partially solved by moving the turntable onto the projector and driving it off the same motor. One theater I ran in still had the drive for the turntable still on the projector. Oh, and selenium rectifiers providing DC to the arc lamps.
+D.E. Bunker I find that amazing, thanks for your input
+Claus Valca Row it depends
on the flim, before the 70s magnetic audio was used, dolby and optical audio
are used since the 70s
"But the human eye can't see more than 24fps"
1sephiroth8 Hard to believe people actually thought that at some point.
Truth be told, it's going to be more logarithmic in practice.
You'll be hard pressed to notice a difference between 24fps and 25fps. But you sure as heck will notice 24fps vs 48fps.
Gamers with the right hardware will tell you that there is noticeable difference between playing at 60fps and 120fps.
The human eye and vision systems are a lot more complex than "frames per second", dealing with constant streams of incomplete input, and yet somehow pieces it all together. Amazing, isn't it?
1sephiroth8 Easy thing for you to say, PC.
PrimeSonicYT I don't know why you say people thought that "at some point." The same set of people still believe it now than did then, the issue is that 24fps is sufficient to provide an illusion of motion, and when you're not interacting with the motion, is generally plenty.
Caleb Jones Keyword: "generally". 24 is fine for movies today because of the motion blur. A solid 24fps without blur wouldn't look quite as good. That is to say, 24 fps seems to be enough to fool us into seeing motion from static images (And that's just a general rule for most people, some can even go a tiny bit less), but 24+motion blur (or just a higher framerate) would look better.
I know you probably already know this, but it's mostly for anyone else's benefit who happens to stumble across this. :p
Matt Hoffman Yeah. It's still potentially an interesting discussion, and leaving good information for people to find is always nice.
So, in addition to the wonderful quality of motion blur in films, it's also important to note that there's a dramatic different between interactive and passive content. Lower and lower frame rates in video games become more and more disorienting and unpleasant, whereas lower frame rates in movies will, at the worst, not look as good. Motion blur also doesn't really help this situation in games, because one of the major problems of low frame rate is that it introduces more latency to your inputs.
Love the in depth look at one of my first jobs. I understood the basics when I worked at the theater but didn't know exactly all this. One cool thing about our projectors is that they had the analog sound just like yours, after the lens, but we had added on digital sound sensors, which were before the lens. The sound output was then delayed a couple seconds so it would still line up perfectly with the frame on screen.
Unbelievably well done animations to show the projectors workings! Great job! One of my favorite videos from the Engineer Guy and crew.
I've got a question: why do modern projectors block the light three times? I get that the flicker rate would go up if half the revolution the shutter blocked the light, but what keeps them from simply blocking the image 1/6th of a rotation, effectively blocking the light as fast as the current flicker ratio, but now having an image on screen 5/6 of the time, instead of 1/2?
Arturo Munhoz We aren't sure exactly. We came up with this same solution, based on what we have read it SEEMS that the shutter must be symmetric or the viewer will notice something odd happening.
Arturo Munhoz A 24 hertz (cycles/second) square wave with a 5/6 duty cycle has a 24 hertz component as well as harmonics. You would be able to see the 24 hertz component. If the duty cycle could be raised high enough, then the amplitude of that 24 hertz would go down, but for reliability and cost reasons it is better to use a multiblade shutter.
Chris W So you mean that those harmonics would be the "something odd" that we would notice? That makes sense to me. It's always cool to see how things can be expressed mathematically and still be intuitive.
The "something odd" is 24hz flicker. The second harmonic would probably be very low and the third (and higher) would be too high to be seen.
Chris W
Oh, okay, I get it now.
So the countdown at the beginning of a film causes the sound and the images to be insync? Or does the first 26 images contain no sound?
RamboX1000 The first 26 frames display an image without any sound and the sound of the 27th frame is stored in the 1st frame.
RamboX1000 The countdown strip functionally works out to feet of film...they are so the projectionist knows where to lock the film in the projector when threading the film initially. The projector motors and particularly the xenon arc lamp take several seconds to get up to speed. This spin-up time needs to be accounted for at the beginning or you'll miss part of the intended film. For example, our old Century projector needed the countdown lead-in framed somewhere on "4" in the countdown so lamp would be up to full arc power by the time the main shutter opened. If we framed on '6' there would be 2 seconds of countdown at the beginning. If we framed on '2' then 2 seconds of the intro to the movie (usually black, sometimes a company logo) would be skipped.
Stig Helmer When advertisement on TV where still shot on film, when edited together, and because of the 26 frames offset, you could notice that there was no sound on the first second of any advertisement clip.
frollard Didn't you love it when other projectionists kept chopping off the header on a reel and eventually messed up your change over? I ran Century and old Simplex (E7s?).
D.E. Bunker Yeah, if someone wasn't paying attention it got frustrating. I would take off the gratuitous blank space at the beginning but it stayed with the reel and went back on when I broke it down. :)
Beautifully explained! Thank you.
Absolutely beautiful! I could watch this for hours.
Instead of dividing the shutter into 3 sections. Why didn't they just shorten the shutter during the slide transition?
Kombaiyashii These is an excellent question. One of the pieces that was dropped from earlier drafts was a bit of the rationale behind the engineering of that step. (You can see earlier drafts at the engineerguy preview page, where you can also become an advance viewer.) So, 24 frames per seconds, fast enough so that you see fluid motion, but most be faster to avoid flicker. A possible solution is to shot at a faster frame rate, says 72 frames per second, but then you have to use more film and the mechanisms in the projector must wove faster. More film is a negative: its is expensive, large rolls in cameras and sent to theatres; faster mechanism more difficult to engineer than a slower one. It would wear more quickly, use more energy, etc. So, the better ENGINEERING solution is to just take the shutter and split it up into three parts. Your questions "why not shorten shutter" is partly answered by this: faster mechanism, more trouble. (Not impossible, but you want to make a mass manufactured object as cheaply as possible. )The second issue is that is seems the shutter MUST be symmetric or the human eye will detect something. In preparing this video we asked ourselves that same question: why not just a sliver of shutter. As we dug into the literature is seems that a shutter must be symmetric ....
***** Ah, thanks for answering.
Kombaiyashii Also, the brain prefers uniformity over 'more on time' -- that 24hz flicker is just as bad when you have 66 or 75% duty cycle. The only solution is to increase the flicker speed and uniformly at that.
***** I think the issue here (that I had too) is that it's not about "show it as much as possible" it's about uniformity (as said below) of the flicker rate... it's counterintuitive but adding more screen flashing over the same image *improves* the perception of the image. My gut is telling me that this would make it worse, but my brain is having an argument. ;) Thank you for another great video. I thought I knew a lot about the topic, but you're making me really think about it. :D Cheers!
Scott Lawrence I had the same intuition! I find it fascinating that by chopping up the image more you improve it.
Why did they make the original "advance film" shutter blade so big if 1/3 would have been enough?
Stefan Zijlstra See my answer to Kombaiyashii ....
***** A thx, i get it
Stefan Zijlstra One thing to consider is that initially the mechanism moved slower (which was easier to build). So originally it did need the full 1/2 blade. When they moved to the triple shutter then it necessitated that the shuttle move faster so it could move down during a 1/6 blade movement.
Awesome video!!!!
This is my only CZcams subscription that I get REALLY excited about.
Only 25 dislikes. Wow
may be they dont' know what films are OR not allowed to watch a flick
This was so cool, but I don't get how the photo sensor transforms the light from the film to electrical current and how that produces accurate sounds.
But... how is it "translated?"
+Xmus Jaxon Flaxon-Waxon III So how does it become current?
Oh right. Light is already part of the electromagnetic spectrum. So it's kind of just playing it, right?
So I guess the next question is, how were the sounds recorded optically? Was a diaphragm used, like the ones in phonographs?
Also how are multiple kind of sounds accurately recorded simultaneously? The Engineerguy said it the film's length and width determined the loudness and pitch of the audio, but aren't there some sounds that are at the same pitch but are still distinctly different?
BTW: Sorry about all the questions and thanks for all the answers you've already given.
+Xmus Jaxon Flaxon-Waxon III You are talking magnetic sound tracks and few 16mm and even 35mm projectors were equipped with them. The standard is optical sound, and if you take a fotocell, and hook it up to an amplifier you point a bright light at it, and run a dark piece of cardboard up and down between the light, and cell you will hear a popping sound on your system speed it up and down you will understand. actually invented in 1904, and not by Edison.
A year later, but hey this is when I read it.
For recording, the sound is converted by the microphones to an electrical signal which would be used to power something that functions much like an ordinary speaker, except that instead of moving a cone to project sound, it moves tiny pieces of metal that act like a shutter. Light is projected through the gap between those two pieces of metal onto film. Develop the film and you have the audio track. This method is the variable density method.
The variable area method which looks more like a wave form, is much the same as the above method, but instead of the speaker like device, it uses a mirror galvanometer to reflect light in such a way as to increase or decrease the width of the beam of light projected through a narrow slit onto film.
For stereo soundtracks you would project left and right onto separate areas of the film.
Playback uses a photocell which responds to varying intensity of light with a voltage. Amplify this voltage and send it to some speakers and you have sound.
As always, Beautiful presentation!
Such a clear and well explained video - so enjoyable to watch and learn
i'm 42 and i had the chance to have an aunt whose uncle had a movie theater in a small city in the countryside here in brazil. i used to go to the projection booth and to the basement under it to fiddle with things when it was closed (i'd always find a way to sneak into the building), and to watch the projectionist do stuff when working. it was still carbon arc, rca projectors. very old ones, but looked good as far as i can remember. the movie theater had a little over 900 seats, two floors, and there was a beautiful and thick red curtain that would open and close. a nice movie theater for a small city in a developing country.
fascinated by how the sound system worked, i would build a thing just to extract the audio from a 35mm doc i had. i used cardboard paper and a flashlight lamp and a light thingy to convert light to energy and connect it to the mic imput of my mom's stereo. fun stuff. there was a movie theater in another city i lived that had a problem of frame misalignment in one projector that would show part of the optical track, and during a ninja turtles session i still remember how cool it was to see the waves being shown while 'go ninja, go' was playing. the song has basically two frequencies of bass, and one bass would look like waves going up and the other like waves going down, and there was all the crazy mids and treble.
later, when i was 15, i got a chance to work for three months at a movie theater that was part of a cultural complex run by the state. the complex was built with german technology and they donated a planetarium. the movie theater had unique seats, and the screen could lift up and be hidden for orchestra presentations. the screen was a little smaller than the screen at my uncle's, but still a standard size, and there was no curtains. the building desing was quite different.
aside from the regular 35mm projectors, they had eiki 16mm and bauer super 8 projectos, and a room filled with a lot of 16mm and super 8 documentaries. there was a week that they had an event showing movies and docs from across brazil and from other countries, little known movies, with most attendees being people from the cinema industry ,and enthuasiasts and stuff.
the projectionists who took turns let me work alone for three days! they'd be there in the beginning only, and i'd close it. it was all illegal. my age for working there, and they letting me work alone having such a responsibility, but they were fed up of it all, little salary, little attention and care from the administration, etc, and they didn't want to miss the opportunity of take the time off and leave me there. well, i loved it! i was showing movies and docs to artists, directors, and other people of sort. one day there was a problem with the audio and i fixed it! it was awesome for a 15 year old!
i had two 16mm projectors and would invite a couple friend of mine to come to my home and watch documentaries. i stopped using and owing this kind of stuff in my late 20's.
Can’t express how helpful and engaging this video was👏🏼
I can't tell you how many times I've seen a graphic animation showing a screw or propeller turning contrary to its motion through the medium, which enrages me to no end. From a shade tree engineer to a real engineer, I graciously thank you for taking the time in that last animation to make sure that the gear ratio between the sprockets and shutter shaft was correct, in addition to the shutter and shuttle timing being impeccable.
Thanks for this fantastic presentation.
Fantastic video! You explained it so simply.
Impeccable. Thank you Bill!
Fantastic presentation, thank you!
Very well explained. Thank you Mr Engineerguy.
What a bloody good explanation video. Thanks!
Bill, this is an excellent presentation. The slowed down close-up of the feed mechanism, as well as the animations, are priceless in helping to understand the workings of this awesome invention. And it goes without saying that your explanation of what we are seeing is perfect. Thank you for sharing this.
I could watch this during all the day. It's so well explained and the graphics helps us to understand in a easy way. Thanks for that!!
Very nice and smooth explanation. Thank you.
Great explanation. Thanks for making these videos.
Excellent job on the final edit.
This is such a super series of videos.
What a clever mechanism, precise and efficient. Always a delight to watch these videos, good work.
As always, pure awesomeness! I admire how you can find mind boggling stuff in seemingly common and boring objects.
Now that was really well done and interesting. Thank you!
I'm always so happy to see new videos of yours in my feed. Thank you for the wonderful videos. Thanks for the information.
Awesome :) I love the way you take some complex ideas and simplify them enough for pretty much anybody to grasp how they work. Can't wait to see what you explain next!
Wow. Another great video. I don't think there is a much better or concise way to explain film projectors with so much clarity. Thank you for your efforts on this video, I learned a lot.
This is fantastic! I worked in a theatre with 35 mm and 70 mm projectors, and you still showed me stuff I didn’t know. Your videos are great!
Thank you Bill for the informative presentation. The amount of ingenuity that goes into design of everyday things never ceases to amaze me.
Brilliant Video with very clear explanation. So pleased I found this. Many thanks.
Well presented, made so simple!
This stuff is just amazing! I always wondered how people came up with the ideas to create these complex mechanisms.
amazing. so incredibly perfectly woven together
This might be your best video yet! I've seen so many of them and this was my favorite!
Wow, the production value of this video (and all your videos) is astonishing
Great video! Very well explained.
Wow what a great guy to listen to and easy to understand
Amazing video. So well explained. Great graphics. Science made simple.
Just discovered your channel. All your content is amazingly pedagogical and well made. Thank You!