Hypercentric optics: A camera lens that can see behind objects
Telecentric and hypercentric optics are very different from our eyes or normal camera lenses. They have "negative" perspective or no perspective, respectively, leading to very unusual images. In this video I show how to use a common fresnel lens in the creation of your own telecentric optical system.
Fresnel lens, 300mm dia. 200mm FL is sold out... www.amazon.com/gp/product/B07...
$5 projection lens on eBay: www.ebay.com/itm/Delta-108-Pr...
Good practical discussion of telecentric optics: www.lockhaven.edu/~dsimanek/s...
www.mii.cz/art?id=626&lang=40...
Idea to use macro tubes for telecentric conversion of normal lenses came from here: www.4photos.de/camera-diy/Tele...
In-depth info on telecentric lenses: schneiderkreuznach.com/applic...
Commercial hypercentric and telecentric lens maker: lw4u.com/
Paper on making telecentric lenses with fresnel front elements: sci-hub.tw/10.1117/12.455256
/ appliedscience
Scanning electron microscope : check XRay imaging system : check Waterjet cutting gear : check Ruler for drawing straight lines : over budget
Don't forget the DeLorean, the cryocooler, the turbomolecular pump, the mass spectrometer and the $20000 Tektronix 5 Series oscilloscope! And surely I'm also forgetting something...
Sputtering setup
The ruler is currently attached to an obscure experiment 😂
this paper have square lines, he dont even try :D
And the ruby laser. He has a tektronix scope? I've used them with my job but the one we have cost as much as the house I grew up in.
"Lens sees around objects... by being so big, it is around the object." ;)
You know how much I don't like clickbait, but I gotta clickbait...
Yeah only works for objects smaller than the lens itself I would think 🤔
@@MLGJuggernautgaming only if you want to look around it from all sides, as long as part of the lens looks past an object even on just one side, it can look "around" it on that side.
I can do the same thing much easier with a cardboard box and two mirrors.
Give me a big enough lens I can see around the world
The "zooooom" sound created by sliding the armature adds to the effect.
It's more of a shooooooooooof really.
its more of a shwoooooooooooooohf really
I thought he was putting that effect in at first 😄. Not his style to add silly effects I thought to myself.
YES!
Funnily enough, the term 'zoom' comes from the sound that the first variable magnification system made when zooming.
Now I really want to see a scene in a horror movie, where in camera, using a MASSIVE one of these lenses, we get to see the killer is behind the person in shot, by adjusting the camera like this. Can you imagine how freaky it would be, at they seem to appear and then grow to loom over them, out of nowhere? 😱
That sounds like an awesome piece of cinematography right there!
@@brenebon6980 AWESOME IDEA
Nevir202 I was actually just thinking a lens like that could be used for a really great sci-fi "mind-bending" effect, where things get all warped and weird. Like a teleportation thing.
Patchwork Productions Damn, that could be awesome too. Use it such that something which appears to be a background, shrinks down behind the subject, and then when it expands back out, it’s different?
This is absolute genius. Or use it to portray a mental illness or great confusion or something. SO MANY GREAT POSSIBILITIES
This broke my brain. In drafting classes, you learn to think in parallel projections, but I had never considered that you could capture images that way. Lots of 3D CAD packages will allow you to switch between perspective and parallel views. It's necessary to produce accurate drawings, but it's really disorienting to navigate a 3D structure without distance cues.
You haven't played enough isometric games :p
Literally the first thought that came to my mind
Seriously though, look into chrome-ball photography. It is even crazier.
I'm always flipping between perspective and ortho views in Blender while 3D modeling. Like at the end of the video, you need parallel projection to compare details on near and far ends of something, and perspective for those vital spatial size and shape cues. BTW, drafting was my favorite class in high school! (Don't tell my physics teacher.)
Went from there to emitter-receiver inside-outside holographic projection-drawing. Still grinding the mental gears.
In a darkened room I pointed a 10" telescope toward closed venetian blinds on a bright sunlit day. I was able to focus an image of the stairway *outside* the closed blinds. The tiny amount of light leaking through the blinds' cord slots was enough to form the perfect image. X-Ray vision! Weird.
This is how they combine the light in a telescope array to produce a single sharper image. They don't need to capture all the light in a giant circle, just specific spots.
If I'm not mistaken that's called a pinhole camera. My curtains in my bedroom as a child did this and would project what was happening on the front lawn onto my ceiling so I could see when the mail man was arriving.
oo I might have to get out my telescope and give this a go I wonder if bird watchers could use it to see through camouflage
@@pchris “Camera Obscura”
@@pectenmaximus231 the game?
The 'dolly zoom' type effect you can get with this is really interesting. I wonder if anyone has actually used a lens like this in film-making
yay, good seeing you here! :D
@@DonnieX6 It's not the DJ... 😂
I was honestly wondering how I could use it in a music video
This thing already works very similarly to how they normaly do a dolly zoom. If you wanted to scale it up, you would need a massive lense.
@@Alex-lc1bv didn't he say that it won't look good beyond 1 meter?
In a parallel universe this is a video explaining these weird effects known as "perspective" and "depth of field" to creatures with hypercentric eyes.
How dare you put the image of humans with 10" eyes in my head.
@@mrmeatman9948 don't Giant Squids have eyes that big?
@mr meat man anime
I find this lens much more agreeable than many things in life with its "negative perspective".
Lol
Lol
I use to use a similar lens for creating orthographic snapshots of objects for CAD use.
That's awesome! This was the first thing that came to my mind when he demonstrated this effect.
Actual 5Head 🍷 Holy shit
That's actually so cool!
@@AppleGameification yes, but the lens is as big as your frame. I mean, maybe there's some moving-lens thing for cars and other large objects? I assume it would be possible.
Me too, actually without even knowing it was called "telecentric"! Just a big magnifier glass with camera/eye attached right at the focal point.
“You know how much I hate clickbait” - And that is one of the reasons that I love your channel.
Yeah, I find myself hardly ever watching channels that upload multiple times a week. Quality over quantity.
The click bait is "Applied Science". I don't even read the title when I see that name.
Well that's a neat looking project. I get some weird enough looks when I cart out a small large format camera in public, so I'm on the fence for whether or not I want to play with something like that... But this does remind me of what was always my favourite demonstration of neat properties of optics: Using a wide open lens to 'focus through' something like a wire mesh screen or chain link fence.
I bring my camera up to the chain link fence and shoot through the rhombus shaped hole ;)
Yeah that's a neat trick. Steve Mould demonstrated it when he was figuring out how to film inside a microwave: kzhead.info/sun/a8aRmNeNql-lm68/bejne.html
A good source for truly huge Fresnel lenses with low magnification is some older TV sets where they are used over the screen. Mainly old-style enclosed projection sets.
Afaik lcd screens have some too, so a trashed large screen tv should work fine.
I had heard of telecentric lenses, and knew a little about geometric optics, but you put it all together. I always learn a ton from your videos.
Honestly never seen anything like this before. I love how you introduce me to, and then explain, all kinds of new and interesting things! Once I get my maker shop set up, I may play with this one. It's easy, straightforward, and would be fascinating!
That bittersweet feeling of a seeing a new Applied Science video but knowing that there probably won't be any more for the next month
You forgot about the Corona lockdown... There might be!!
Aperture Science. We do what we must, because, we can.
the cake is a lie
Okay. The test is over now. You win. Go back to the recovery annex. For your cake
For the good of everyone, except for those who are dead.
Cave Johnson!
For there's no use crying over every mistake, We just keep on trying 'till we run out of cake.
The sound the camera slider makes is a cool sound effect to accompany the change in focus.
This channel always blows my friggin mind!
Really cool, as always! I'm glad this effect is rather easy to reproduce, no electronic microscope or other crazy gear needed :p
The first law of physics: There are no free lunches
One of the few channels that can have a clickbaity title yet still undersell the contents of the video.
Very interesting, I liked how at the very end you included what real world examples it would have. Very interesting
I really want to see someone mix tele- and hypercentric optics into one of those VR games/demos that make use of hyperbolic space. The combination of the two seems like it could produce a very interesting result.
Hyperbolica now has a release trailer. 😄
Fascinating, I had never heard of anything like this. Thanks.
I remember having an idea similar to this back in high school.. I thought on how mirrors could reflect things we could not directly see with our eyes and quickly learned the advantage of angles. The fact that the lens is so large is helping get those light rays into the camera's sensor. I've never thought of making a lens out of the idea. I truly enjoy the video and the explanation on how it works and how it can be built. Great stuff!!
Reminds me of Vision Mantis 3D microscopes. Basically moving your head side to side or up / down will allow you to see around the object you're looking at. Very neat, very useful when working with tiny components on PCBs
Didn't even notice the clickbait title. I never need to read the title of your videos to click on them XD
If you've heard of lenses that can see behind themselves (Nikon 6mm), it's not hard to guess what this would be about.
Is it really clickbait tho?
yeah, I'm sold at the Applied Science part
@@KahruSuomiPerkele yeah, but "video with slightly misleading title" is so much more of a mouthful. Lol.
Good, now I can use this lens at the poker table.
knowing the limitations to a system and the failures that came with a project help a lot in learning. Quality content time and time again.
Hey I want you to know we absolutely love your work and also understand your channel is highly underappreciated for what it is worth. Hope you keep making these informative videos out here. Thank you for being awesome. Love.
“Negative perspective” reminds me of a lens my friend had that had a minimum f-stop of less than 1. I always wondered how that was possible.
I think that the f-stop of less than 1 isn't related to telecentricity, as Leica makes an f0.95 50mm lens that has normal perspective.
The maximum focal ratio is determined by the distance of the lens to the sensor/film divided by the diameter of the lens. This is effectively the flange distance divided by the throat of the mount. A camera with a flange distance of 50mm and a throat of 25mm will permit a maximum focal ratio of f2, while a camera with a flange of 25mm and a throat of 50mm will permit a focal ratio of f0.5. It isn't uncommon for lenses to protrude inwards and past the throat of the mount. This is less common on SLR cameras due to the mirror requiring clearance to move, and more common on mirrorless/rangefinder cameras because of the lack of a mirror. You typically don't see lenses with such high focal ratios because of the increased amount of correctional elements required to produce a quality image.
@edo The theoretical maximum if we want to have well corrected lens and have the usual f# to light gathering relation is NA = 1, f/0.5 lens without going into immersive setups.
So it's like orthographic projection in real life, sort of?
Orthographic projection = telecentric optics capture light in parallel so you can only see things the size of the lens and smaller. Hypercentric optics like in this video require even bigger lenses for the same object, in order to capture light that comes from behind it.
I am amazed this is the first time I am hearing about all this. It is such a fascinating concept it deserved to be widely known.
Extraordinary content! Can never expect the topic of the next video but it is always fascinating!
Thank God! An interesting KZhead video!
Albeit a short one. I'll take it anyway.
You could actually look behind the moon if you had a Fresnel lens with a diameter approx the size of the Earth...
We'll call that a stretch goal.
Could gravity lensing caused by massive stars be used in this way?
Cool stuf! I appreciate the variety of things you work on. Your explanations are great.
excellent work once again, I love the detailed and straightforward explanations
Really interesting! A while ago I made some reverse perspective images with a parabolic mirror, but the images had a bit of distortion and the mirror got scratched. I wonder if it's possible to make better images with an accurately positioned mirror.
that is good idea! how about fresnel lens not straight but with curve, like attach it to horizontal material with hole, pour in hot water to make sift plastic for fresnel lens and then let it cool and it must stay in shape
This reminds me of chrome-ball photography, where it technically sees 360 degrees, so long as you process it and have enough resolution.
really good and big fish-eye lenses do take in a view of 180 degrees...
That was utterly brilliant, particularly all the fabrication and practical details at the end. Thanks.
Wow the way you elegantly explained how an aperture functions. Wish I saw this video years ago
The “nothing lens” has focal point at infinity :)
Idk, are we actually Euclidian?
just glass has focal point at infinity. I am searching now for lens with imaginary focal point (i)
Before watching the video: Me: "Sweet. Now I'll be able to spot invaders hiding behind my back yard fence." After watching the video: Me: "Sweet. Now I'll be able to spot invaders hiding behind a very thin pole that's less than a foot away from me."
Useful for watching out for Creed.
@@dakel20 That guy from the office with the mung bean sprouts?
Just build a tower in your backyard with... uhm a lens that has a larger diameter than your backyard (not sure how to work this out practically) and then you could! I guess you'd have a better chance to let people living around you install pan tilt zoom cameras on their terrain, and even that's a long shot.
Sorted. I don't have any very thin poles in my yard.
Thank you for showing the subject of the video right away, instead of making us wait (or skip) to see what we clicked for.
For anyone searching the terms: what you're describing when you talk about a telecentric lens system is a *front*-telecentric lens system (it accepts rays that are parallel in object space, and it "sees" in an orthographic projection). Camera and instrument manufacturers also take an interest in *rear*-telecentric lens systems, which have normal perspective but have the convenient property of making the rays parallel at the focal plane.
I wonder if you could use a couple cameras to make some sort of crazy 3D scanner.
You could, but it would be crap compared to just using a single camera that moves around the object (or rotating the object itself while the camera stands still).
@@RFC3514 using more cameras is better if you have the budget, since you can locate each camera precisely, and extract coordinates more easily. Another great thing is that you can scan objects in movement with such a setup. But only a pair will make for a somewhat poor scanner, if you only take a single shot, though it would divide by 2 the number of shots required.
@manaquri - You don't need to "locate the camera", the photogrammetry software does that for you. It's far more important to have lenses with as little deformation as possible (or at least a _known_ deformation, that can be compensated in software). Scanning moving objects with CMOS cameras (i.e., 90% of the cameras used nowadays) is just masochism (and not just because of rolling shutter artefacts; there are other issues, especially if you need to combine data from multiple cameras). If you have a decent budget, use LIDAR-style scanners. If you're using visible spectrum consumer / "prosumer" cameras, then the image geometry (lens deformation and resolution), the lighting, and the number of images, are the most important factors in getting an accurate photogrammetric model.
light field camera next?
I always appreciate your videos. Thanks for the hard work!
You always make videos about things I’ve always wondered about but couldn’t figure out how to ask. Like, why is their perspective and why can’t we image things without it? And blam. You answered all these questions. Thank you.
OK, one last time. These cows are small… but the ones out there are far away. Small… far away…
My first thought. Guess it turns out Dougal was right after all...
Burger
I find it odd it has the same effect of moving your head to one side to see whats behind the object, i mean, just look behind it..
I find optics really interesting because it seems daunting at first, but concepts are pretty easy to comprehend. Just from the thin lens equation you can calculate a lot.
Very nice demonstration. We have indeed used telecentric lenses with machine vision for inspecting wedge wire filters screens.
Father Ted reference!
Sans any cute Moo Cows. LOL.
kzhead.info/sun/gLGie92em2iedGg/bejne.html
How big smartphone cameras will be in 5 years
*_Samsung_*_ wants to know your location._
imagine thinking we won't be eating the dead in 5 years.
You don't attach a telephoto lense to a camera... you attach the camera to the telephoto lens...
@@Cole-ek7fh we do already. Tons of dead animals everyday
Nah they'll just have 200 small lenses
Finally got a use for those old overhead projector condenser lenses then. Seen this with having them up close, but till now never knew what it was, and the applications.
This is so fantastic!! Thank you for bending our mind - every time you create a video!! :)
Loved the video! Sadly, a very large percentage of videos on YT that get the most views, are the type of videos that dumb people down, or don't help/educate others. You deserve way more views, like many other YT channels, including myself.
That was a very nice comment, right up to the last few words
I almost agreed til you stroked your ego at the end, guy. Get over yourself.
Can it see behind my girlfriend's motives?
Seems as if there are a lot of guys that have the same concerns that I do.
@@BoffinGrusky Perhaps it is all the same woman?
easiest way to see behind her motives... ignore her.
This thread says a lot. Sad they are all so stereotypical that they've evolved the ability to universally deceive and manipulate us. Its almost like 63% of women lean hard left in politics... oh wait, they do.
@@Baigle1 still. Ignore them. They'll come around. If all do at the same time they'll come around faster instead of chasing the white knight
Great video!! Thanks Ben. I believe this is very similar to how 3d light-field photography works too. Brilliant stuff. Very cool.
Hey, In machine vision we often use telecentric (no perspective) lenses quite often for inspection and measurement. They are fabulous to work with, but usually the overall size is the constraint we face!
Do not watch this video drunk, your carpet will thank you
Was anybody else distracted by the fact that the word "fresnel" was actually pronounced correctly in this video?
It wasn't though. He didn't say the S.
In my environment it's always pronounced correctly, I don't know any other way. So no, I'm more distracted by your comment. ;)
Simon Tay it’s French, the ‘s’ is not pronounced
@@Davvg oh, ok. I didn't know it was a french word. Must've been invented by a french person named fresnel.
I was a little stressed out that maybe something was wrong. So glad youre still here doing these!
I work in industrial automation and we use telecentric lenses all the time. really magical for machine vision, inspecting anything that has to be parallel or non distorted. looking at piston ring grooves for example and taking precise measurements. or looking down any type of tube for defects, we use telecentrics all the way from a few millimeter fov up to a few hundred millimeter.
Ok I'm tired with awesome shit! Make a micro thorium molten salt reactor! Yes in your garage! You're that smart!
LOL the lens is larger than the object its observing, of course it can see around it
TheZenbudda right? "You know how much I hate clickbait" proceeds to clickbait..
How is this clickbait? What were you guys expecting? The only other way to see what's behind a solid object is to bend space-time. Not even all of the combined power of every power plant on Earth can come close to performing that feat.
This would be a great practical effect for a character that can read others' minds.
Someone should make a game demo that gives the player "hypercentric vision". I think it'd be interesting to be able to freely position and explore with a hypercentric lens. We'd also get the benefit of seeing what kind of images a "perfect" hypercentric lens would produce (i.e. One with an arbitrarily large diameter and without chromatic aberration).
Should be possible with raytracing. Would require programming the camera a bit differently than usual, though. Raytracers usually treat the camera's location as the focal point and point of origin for the camera rays and the rays passing through the image plane as they spread out, with field of view determined by how far the image plane is from the point of origin. That would not work for a parallel projection or a hypercentric one. Instead of treating the focal point as the point of origin, you'd need to use the pixel's location in the image plane, and allow the image plane to be scaled instead of always being normalised. From there, parallel projection is easy: just make all the rays point in the same direction. Perspective projection seems like it would be a matter of changing signs in the usual equations to get the same directions as the usual approach. Hypercentric projection might be a case of pointing the rays toward a point in front of the camera, so they converge on it. Like perspective projection in reverse. It almost seems like it could be possible to have one set of equations that could cover all three cases. Except... parallel projection is the limit of perspective projection as the distance between image plane and focal point goes to infinity. So, there's that hope dashed.
I didn't know about hypercentric, but this is the clearer explanation of telecentric lenses that I know of.
2:49 What a beautiful explanation for aperture! Thanks man. Never thought of a lens aperture this way!
Implications of snells law, a huge lens, and small objects. Nice video. Very intuitive demonstrations.
Thank you so much for making these videos. I hope you continue to do it. It is really inspirational to those of us who think critically and outside the box.
Another GREAT video, TNX 4 upload !!!
I know theocentric and hypocentric from working for production line. But I never thought the theory is actually this simple with the aperture. Thank you for showing this
Thanks for cool demonstration and very clear great explanation!
Gah! Brilliantly simple description with those hand drawn diagrams of how an aperture selects certain light rays. Well done!
Very cool. It's funny that you mention metrology since alot of optical metrology systems I've been looking at recently use telecentrics optics. The manufacturers make it out as if though it's some crazy new technology when in fact we've know all this for many many years.
Oh... this would make a great demonstration for teaching orthographic perspective in a drafting class... I'll have to make a note of this. Thanks for the ideas!
You NEED to get an optics channel to make you a really good lens like this but a real one that can preserve lines like the special wide angle lenses can. I would absolutely love to see these demos with less distortion and aberration
Thanks for this video. Was thinking it would be cool to have a telecentric lens for longer distance microphotography and now I understand a little better why that isn't necessarily possible.
A very interesting and surprising topic as usual. Thank you :)
Such a beautiful effect
Amazing as always.
thank you for showing it quick to prevent the clickbaityness. youre a good person
very cool thanx for sharing lots of potential for new applications
HOW DID I NOT SEE THIS VIDEO WHEN IT CAME OUT? I was actually looking into this exact same thing, making a lot of drawings and simulations on how to construct such objectives. Now this
yet again we see the amazing utility of the concrete mold for diy projects
The materials make a neat sound effect too!
The protection TV lens came from a single tube CRT projector. Tri-bean (RGB) sets do not have a diffraction grating behind the tube face since it each color is a single beam. They do not emit x-rays. The warning means there was a grating in the tube that lens mounted to.
Very cool. This is one of the techniques used in reading and etching holographic data into a medium. Next you try what polarizing can do with this setup
I love your videos!! Long time watcher. Please make more greatness!
Oh neat, I've seen this in action to an extent when I wore glasses. My glasses could slightly bend light sources like LEDs and traffic lights so the glowing light was displaced, so much so with higher frequency light that I could see the part that was supposed to be lit unlit. Very noticable with say the LED on a TV box. Rather hard to describe in words, and blew my mind
I'm just glad you correctly described aperture. So many people believe it squishes and stretches the light.
This was a very cool video. Again something I didn't know I was interested in until you brought it up!
There is NO other channel where I would watch a video with this title.
Okay this is really cool and I'd love to see filmmakers take advantage of this effect. I could totally see it working as a disorientation effect.