This is so much better than most videos about how lenses work. The other ones are frustrating because they just leave you with more questions.

@tingoyeh4903

Жыл бұрын

Well said. Even my high school physics text book tell me one single convex lens can make a perfect image everywhere, like if your object is 2f from lens then you will get a perfect image on 2f.

@combustivelsemimposto4710

Жыл бұрын

I agree!

There seems to be no limit to the number of technology fields that you are great at explaining/teaching. I would have loved to have you as a teacher/professor IMSAIGuy. Thank you for making these videos for us fine sir! Fred

Thank you for this. Just a historical note regarding the Cooke Triplet: it was designed and patented in 1893 (not the 1930's) by Dennis Taylor who was employed as chief engineer by T. Cooke & Sons of York, England. Its earlier provenance makes it the more remarkable.

@okaro6595

8 ай бұрын

Interestingly the Cooke Triplet was f/3.5. Still modern entry level DSLR lenses typically are f/3.5 (at the wide). Some traditions live long.

@tuunaes

13 сағат бұрын

Cooke Triplet is also basis for all zoom lenses: Moving center element in between outer elements changes its focal length. But also aberrations change and are harder to control and it took until 1930s to get first zoom lens into production.

Very cool. I've wondered about this, off and on, for decades and never got around to looking it up! One thing I *think* might be missing is that you can use materials with different indexes of refraction for each lens to tweak it even more.

@IMSAIGuy

11 ай бұрын

yes, glass with different dispersion, to correct for color aberrations. classically referred to as crowns and flints. I talk about it a little: kzread.info/dash/bejne/gqylyqNsZ8WxpKw.html

Incredibly educational. I'm new to the camera hobby. (3 years). And was curious to find an explanation. Thank you.

Thank you. Yet ANOTHER field of interest that I have always had great interest in. Your experience and expertise is seemingly endless. Thanks.

Really interesting. I've been a photographer for decades, and I'm a little ashamed to say that however mind-boggling I always found lens techniques to be, I know way too little about the 'glass' that I use. Thanks and thumbs up.

Fantastic explanation. Would love to see more!

Very interesting explanation. Always wondered what a field flattener does to light. Thanks for sharing.

All the years I did 35mm never thought about this. Did alot of macro shootings. Very interesting material. Thanks.

At 06:50 Yes, the use a lot of elements for a single lens. More so if you consider that they use a very narrow band UV light source. Chromatic aberration is therefore limited, EDIT: Good to see that you mention it also.

Fascinating... Well done. I really learned a great deal. Thanks for taking time to do this for us.

Thanks, Time has never been that fast. So enjoyable to watch and learn

Hey, just wanted to say thanks a ton for teaching in such an awesome way. You made those tough concepts a breeze to grasp.

@IMSAIGuy

11 ай бұрын

Great to hear!

I just came to check what the elements and groups mean in lenses... Ended up watching the whole video and learnt so much!

Fascinating. Thanks for sharing

Thank you very much for all the information and details, very well explained, it would be great to find more videos like this.

This is the best vedio on optical engineering. No one ever just gave this 15 min lecture...yiu are a god to me man

Wow! Very cool! Always wondered why so many lenses!

Thanks for your explanation!

This is absolutely amazing thank you! I am in awe

this explains pretty well tho why it took a (comparatively) long time for compact cameras to gain lenses that went wider than 35mm (equiv.) guess it's just that - harder and more expensive to make light bend around alot more at wider angles

VERY GOOD AND QUICK LENS EDUCATION !

Awesome explanation, thanks

this is phenomenal, thank you! Subscribed!

Coma is Vietnamese for vampire. When I was in Saigon in 1972, I went to a movie called Coma. Vampire. Except this vampire was a woman who wore white and played piano in the forest on her time off.

Super interesting, thanks for posting.

@IMSAIGuy

3 жыл бұрын

I like the aperture logo

That's really interesting how you explain how lenses is working, so most people can understand, or at least have an idea about it. I subscribe to your channel because you have a lot of good interesting content. Greetings from Kenneth (Denmark)

Amazing video! Would love to see a video about a curved image sensor would change this. Also about how the lens in our eye works.

Very Informative video, the kind of video I was looking for

Fascinating stuff! Thank you! I wish there were more videos on KZread about optics and optical design.

@IMSAIGuy

3 жыл бұрын

I could teach you how to do lens design and loose all my viewers. They only care about RF. In silicon valley I can count the lens designers on one hand. My buddy in San Diego designed one of the mars rover lenses. He is quite proud.

@wim2874

3 жыл бұрын

Fully agree that their should be more exellent youtoube video's like this about optics. Maybe a second channel for optic geeks only?

@luomoalto

Жыл бұрын

@@IMSAIGuy I’m one of those lens designers in Silicon Valley. There are more of us these days, but not that many good ones. 😁

This is so cool! Thanks for sharing. I believe the optical coating is also important, isn’t it to ensure the light entering the lens is within its comfortable zone (generally using thin film reflection to bounce back the other ones)

@IMSAIGuy

Жыл бұрын

coating does two things 1. increases the light transmission. 2. decreases stray light reflections

Very nice explanations :)

Thanks for the information!

Another trick they've been doing recently for mirrorless cameras is that since you've got to apply digital processing to the sensor image's anyway, some corrections can be done in software and the lens design can be optimized for other factors. If you squint this is a analogous to the curved film trick you mention in the video.

@IMSAIGuy

6 ай бұрын

I know they correct for distortion and cos4, not sure about focus

I really enjoyed this! Thank you very much :)

Great video, very interesting!

Thanks for the information. I'll pursue Omnivision. Optically, the setup is simple : a 20D lens is held in front of the eye being examined while a cell phone camera is positioned 30 mm or so away from the 20D lens to capture the aeriali image produced by the 20 D.. The cell phone illumination and auto focus do the job. Some people capture the image as video and look for the best frames. Thanks for your suggestions.

Wow ! Very interesting ! Thank you.

Ahh this is next level stuff !! Thank you good sir

Thanks, awesome content.

Very good! Thanks!

So interesting ! I am searching for the specs of a Canon FD 85mm 1.8 lens in order to manufacture the front element. Do you have any clue where to find it ? I would be so grateful

@IMSAIGuy

2 жыл бұрын

You will not find any specs. They are secret. Most large camera companies have front elements for sale. especially for expensive pro lenses. Having a single element made would cost more than the lens is worth.

I found this very informative and interesting, thank you. I recently did a BINDT CAT 1 IR thermography course, cat 1 being the starter level! I intended to dive deeper but are the lens makups very similar to photography lenses or is the thermal camera purely dependent on the sensor technology to achieve a desirable image? Guess I may need to do the Cat 2 course!!

@IMSAIGuy

5 ай бұрын

resolution of thermal cameras is low compared to film or CCD. so lenses are simple (one element). they are also made of exotic material (Germanium).

Nice, I just discovered this. Good video. Off the top of my head, two other famous cameras that use a curved film plane are Agfa Clack and Agfa Click. Of course these were just really cheap, essentially toy cameras with single element lenses (or at best an achromat) but pictures are sharp thanks to the curved plane. I still use my Click from time to time.

Now consider the trade offs for something like euv. Where they reduced the stack to just 7 reflexion lenses because it is so hard to refract the light without loss

Very interesting, thanks. That field flattener looks a bit like a Schmidt plate. Am I on the right track?

@IMSAIGuy

3 жыл бұрын

They look similar but are quite different. The Schmidt plate is at the aperture stop of the system. There is a Fourier transform from the aperture to the image. the image is in x-y space and the aperture is in angle space. The incoming wavefront will be phase corrected by the plate to correct for spherical abberation and I think astigmatism and coma. it is difficult to grind an aspheric mirror so the job is given to a thin piece of glass that can be warped, ground flat, and unwarped to result in the shape.

@MrBanzoid

3 жыл бұрын

@@IMSAIGuy Thanks for the explanation. I'ii have to try and find out a bit more about this topic.

Thanks for the clear explanation of why we need so many layers of lens in cameras. I have a stupid question, I am wondering why our eyes can do it so good with only one lens? Is the lens in our eyes any special?

@IMSAIGuy

2 жыл бұрын

kzread.info/dash/bejne/qY5lxsWrpdu_gpM.html

"The Cooke triplet is a photographic lens designed and patented in 1893 by Dennis Taylor who was employed as chief engineer by T. Cooke & Sons of York".

Ive watched this video a lot. There's some smart people in the world man

I have only one word for you sir "Genius"

@IMSAIGuy

4 ай бұрын

no genius, I did optics for 30 years.

Just wow Very impressive

Awesome, thanks!

This was so fascinating! Thanks for making this video. :) I could watch a whole series on lenses.

Hey there. It is my first time on your channel and I am quite interested in learning more. Namely, I am interested in the detailed process of how you reverse engineered this lens, what software do you use, and the like. I am currently trying to design simple LED lenses, which do not require image fidelity and only usually attempt to narrow the light beam from a beam of 120 degrees to a one of 30 degrees or so. I was experimenting with the aspheric lens equation and got somewhat stuck. I was using open source software and mathematical solvers like sage. If you find the time to talk more about lens design and, for example, what equations, curvatures, and different types of glass there is, I would love to watch this content. The field leveller glass, for example, trades width for depth to achieve the outcome but how does it do that and do the surface follow an equation. Are lens surfaces all mathematical and how are they obtained (I mean, how are the formulas obtained). At a minimum, I would like to know what computational tools and/or software you use. Thanks!

@IMSAIGuy

4 ай бұрын

I used ZEMAX, OSLO, Code V, LightTools. once in a while MATLAB or Octave for specialized calculations and color theory. OLSO may have a trial version, you can also try WinLens3D

I find your videos helpful, because I'm trying to design an eyepiece that magnifies the image of a camera viewfinder. I want to mount the eyepiece ontop of the viewfinder. A simple telescope doesn't do the job, because the aperture is too small and it cuts off some parts of the virtual image.

Taylor, Taylor & Hobson was the name (Cooke Triplets)

Awesome job. Can you share the prescription you recovered from that last sectioned lens?

@IMSAIGuy

Жыл бұрын

that was decades ago

@IMSAIGuy

Жыл бұрын

it is a type of Zeiss Sonnar

@INCYTER

Жыл бұрын

@@IMSAIGuy Thank you, Sir!

Thankyou! Could you suggest how one gets more coma in a simple cooke design?

@IMSAIGuy

Жыл бұрын

more off axis astigmatism

Good show great content

imsaiguy: Thank you for this informative video. I just have only a cursory interest in lens design. I have not heard "IMSAI" for many years, this was the beginnings of the micro-processing revolution started by Intel, Zilog etc. started in the mid-1970s.

Excellent video, I would love to learn more about how to go about designing lenses. I am currently working on a project that uses Kodak disposable camera lenses and adapts them to other cameras.

@IMSAIGuy

8 ай бұрын

get the book Modern Optical Engineering, by Warren Smith get the software 'Zemax' study for about 5-10 years

@andrewdavies2358

6 ай бұрын

You could try a program could OSLO. It's an old version of a program like Zemax. It lets you model up to 10 surfaces for free. So if you're doing it unprofessionally that would be a good starting point. I use Zemax and it's great, but the license is expensive.

@IMSAIGuy

6 ай бұрын

@@andrewdavies2358 my boss used OSLO and I used Zemax. we would both run optimizations to see if either has missed anything. Didn't know about the free 10 surfaces. that barely lets you design a triplet, but certainly would be useful for the astronomy crowd.

I think I found a new wormhole to dive into. Any advice on how to go about doing more studying of this type of stuff? Are there any companies that'd make the lens elements to order?

@IMSAIGuy

5 ай бұрын

I would get the book Modern Optical Engineering by Warren Smith if you are interested in lens design. Yes there are prototype houses for lens elements. It is way too expensive for DIY stuff. you can get some generic stuff at places like Edmund Optics

Now they can use software to correct images and use much simpler glass arrangements. Saves weight and complexity. It might work in practice, but does it work in theory?

11:45 they also use this for another effect, the fibers aren't actually straight thru, instead they're all twisted up to turn the image right side up.

I think something that's crazy about the lens design, is that you didn't even mention focussing/zooming yet

@IMSAIGuy

5 сағат бұрын

this was a very simplistic look and only really addressed one aberration (field flatness). Yes zoom lenses add way more complexity and lens elements.

Can you give the name of the optical design program? Would be fun to dabble in it

@IMSAIGuy

3 жыл бұрын

Zemax

6:22 i mean a RC mirror set is pretty great and it inly has 2 elements.

well explained! could SLR or DSLR lens designers use the cell phone field flattener lens type to make a minimalist sise lens for full frame cameras? too hard to grind complex shape in bigger lenses?

@IMSAIGuy

8 сағат бұрын

Field flatners have been used for 100 years

Do gasses between glass elements act as their own element as well? ie Would different gasses between glass elements change things?

@IMSAIGuy

Жыл бұрын

I have not heard of gases. I have seen liquid.

Looks like curved camera image sensors are going to be a thing in the next decade or so from the recent porotypes that were shown off. Wonder how that will change lens design.

this video was really great I have watched all your lens-related videos and really like them can you make one about UV lens protectors what effect do they have? thanks also, why do reversed lenses work so well for macro?

@IMSAIGuy

3 жыл бұрын

short answer is the lens is already happy having the lens close to the film. so turning is has lens close to subject.

@IMSAIGuy

3 жыл бұрын

what do you want to know about uv filters?

I would be interested in more videos like thsi, i have been trying to research building a triplet telescope for a while but i havnt found any triplet sets so the idea is to find out how to select individual elements, problem is nobody actually explains it well at all. Are there any open source tools for this? Or any actually useful resources?

@IMSAIGuy

12 сағат бұрын

I would get the book Modern Optical Engineering by Warren Smith if you are interested in lens design. CAD tools I've used: ZEMAX, OSLO, Code V, LightTools. once in a while MATLAB or Octave for specialized calculations and color theory. OLSO may have a trial version, you can also try WinLens3D

Great video! Has anyone explained how the focal lenght of a camera lens works? Like, where do you "fit" say 800mm of distance in a 800mm lens? Because most often, you cant, most lenses aren't even as long as their focal lenght. (Unless ofc there is some glass trickery involved)

Wow, that was great

Which the lens optical design software you used to reverse engineer the design.can u do a video on lens rehousing.there is not much material available about rehousing.or suggest books or online material you know about it.This was one great video.thx

@IMSAIGuy

Жыл бұрын

lens cad program: Zemax mechanical books: Opto-Mechanical Systems Design by Paul R. Yoder, Jr. Fundamentals of Optomechanics (Optical Sciences and Applications of Light) by Daniel Vukobratovich

@jetwayartisman

Жыл бұрын

@@IMSAIGuy Thanks you

Where do I start if I want to measure a lens and figure out its parameters? I have a huge aerial photography lens, the first element is nearly 6 inches in diameter, and aside from focal length and aperture, I'm a bit in the dark. The front and rear halves unscrew from the shutter (no adjustable aperture, just open-close). Taking a giant lens spanner to the front, it's just two elements. The rear has 3 elemens, one single and two glued together. Since it's fixed focus as well, I'm pondering how to make it adjustable focus - the easy answer might be to mount the lens on a rack / bellows type movement, but I've been testing it out on the kitchen counter using a sheet of paper to gauge the focus and a ruler to see how much movement is required, and for the range of distances I'd like to use it at, I need over a meter of travel. The bellows would be bigger than the camera and require some support to keep out of the optical path. Just for fun, I calculated the hyperfocal distance and its around a mile.

@IMSAIGuy

8 ай бұрын

that is a very complicated process. you need to measure the curvatures of each surface and the thicknesses and spaces, then you will need to know what glass type is used for each element (index and dispersion). these will all require special instruments. once you have these number they will not be accurate enough. you will need to put them in an optics design program to adjust them.

Please send links to (free or demo with limited capabilities) optical CAD programs you recommend to start playing with.

@IMSAIGuy

3 жыл бұрын

Zemax. I don't know if they have a demo version

Interesting! I know virtually nothing about optics besides what I vaguely remember from undergrad physics class. I suppose nowadays one can use computers to optimize lens design in ways that weren't possible in pre-computer days?? Must be even harder to design good zoom lenses then?

@IMSAIGuy

3 жыл бұрын

Before computers they used ladies with adding machines. The job title was 'computer'. Each lady would be given one ray to trace. Computers make it much easier to design (and poorly design). I've seen lots of 'kids' that get an optics cad program and think they can design lenses. It doesn't go well. Yes, zoom design is a real art.

could you recommend some books on how to design and calculate these lenses?

@IMSAIGuy

3 ай бұрын

I would get the book Modern Optical Engineering by Warren Smith if you are interested in lens design. CAD tools I've used: ZEMAX, OSLO, Code V, LightTools. once in a while MATLAB or Octave for specialized calculations and color theory. OLSO may have a trial version, you can also try WinLens3D

@king_james_official

3 ай бұрын

@@IMSAIGuythanks a lot!

I wish you had covered the Tessar lens.

@IMSAIGuy

4 ай бұрын

just a triplet with an achromat back element.

@gordonbrown5901

4 ай бұрын

But it’s a great lense.@@IMSAIGuy

This is cool. I've been writing a renderer (for fun) and want to add realistic camera models. This kind of reverse engineering would be an awesome starting point. And you could try different parameters in the model, and see what the effect is. I'm not modelling wave effects so much, and no quantum effects, but it would be fun to play with.

@IMSAIGuy

6 ай бұрын

the big boy lens design CAD packages allow you to render an image through a design. 2D only but it gives you some insight. 3D is possible for non-sequential ray tracing but will not have many of the aberrations included.

@tolkienfan1972

6 ай бұрын

@@IMSAIGuy the fun part for me is the learning and design/coding. :-) My code isn't intended for lens design. It's intended for rendering scenes (vfx). Being able to include a realistic lense helps match a simulated scene to a real one, and also adds aristic range

this is why I love youtube!

How eyes produce high resolution image with just cornea and one lens?

@IMSAIGuy

Ай бұрын

kzread.info/dash/bejne/qY5lxsWrpdu_gpM.htmlsi=zmnkN9-E5hmBH8wP

There are also physical limitations. DLRSs have the mirror s the lens is mounted typically at 45 mm from the sensor and the lens cannot go much deeper. Yet some lenses have focal lenghts as small as 10 mm. On telephoto the problem is the opposite. You want to keep the lens short, shorter than its focal length. Zoom lenses naturally add their complications.

I'm curious: Is that a mathematically accurate statement to say that a perfect lens doesn't exist? If that's the case, is it also true if you replace surfaces with a smoothly changing refractive index gradient?

@IMSAIGuy

Жыл бұрын

gradient index lenses have their own problems and are also not perfect.

@mikafoxx2717

4 ай бұрын

I think using mirror lenses could get more corrective thanks to lack of dispersion effects.

The Minox spy camera needed the curved film especially for copying documents.

Wow. Went a bit beyond Vi= Vo ÷ D. I'm interested in taking digital images of retinas with a cell phone. But security disallows cell phones. Where I work. Anyone know where I can obtain a 16 mp or better cellphone sans the radio?

@IMSAIGuy

3 жыл бұрын

Omnivision sells demo kit boards for their products. MIPI interface. you can put any MIPI camera module you like on it. www.arrow.com/en/manufacturers/omnivision-technologies/programmable-devices/evaluation-development-boards-and-kits

I wish this video was two hours

Current cheap plastic film cameras similar in build to disposable cameras also bend the film.

WA lenses has more complicated design mainly due to existenece of a mirror in SLRs which mimposes higher distance from lens to film/matrix. Extremly wide lens for large format or rangefinder camera is build of 6 to 8 lenses.

@IMSAIGuy

8 сағат бұрын

the SLR back focus requirements usually adds about or or two elements. of course the large format lens does not need as high of an MTF which helps. The Hasselblad HCD 24mm f/4.8 Lens still has 14 elements. and the Voigtlander Nokton 21mm rangefinder is 13 elements.

@marcinp.8108

7 сағат бұрын

@@IMSAIGuy my experiences with LF lenses are that theirs sharpness is on par with SLR (not only medium format lenses), while design is much simpler (6 or 7 lens Gauss design - Schneider Super Angulon). 35mm lenses are more complicated, probably due to the vignette canceling formula (LF WA lenses use a central gray filter).

Where I can bay the lens? is the question?

@IMSAIGuy

Жыл бұрын

lots here: www.edmundoptics.com/contact-support/catalogs/

@rolandocaraballo

Жыл бұрын

@@IMSAIGuy Thanks!

I'd sure be interested in reading your Bio or CV. Can you post it? Better yet, can you do it as a video?

@IMSAIGuy

3 жыл бұрын

I keep things to myself but here is quickly: degrees math physics silicon valley 1980 retired 2014 jobs: software, hardware, optics, physics, manager, director, consultant, expert witness 55 patents

@orbita1

3 жыл бұрын

@@IMSAIGuy wow, we're not worthy

What about making one for kicks.

Have you ever tried a magnifying lens? How many elements does it have? Does it work?

@IMSAIGuy

6 ай бұрын

kzread.info/dash/bejne/gqylyqNsZ8WxpKw.htmlsi=iujWGaIaTZHKHeYl

What I don't understand is the principle of zoom. How the inventor of zoom got the idea and who invented it first. I don't find really satisfying answers.

@IMSAIGuy

3 жыл бұрын

en.wikipedia.org/wiki/Zoom_lens#:~:text=The%20first%20true%20zoom%20lens,starring%20Clara%20Bow%2C%20from%201927. what is not satisfying?

9:05

Why is a Camera Lens so Complicated? Because light behaviour is complicated.

@mikafoxx2717

4 ай бұрын

Ask a quantum physicist what light is, and watch them sweat..

I was super interested like minute 9... Sorry, as much as I wanted to learn about lens theory, this just drove me to loose all interest! Thank you for this great explanation but I just realized I am just a consumer and purchasing any lens will give most of the world pretty good results. Again, I am just a consumer trying too get nice photos.

@IMSAIGuy

Жыл бұрын

visit Ken Rockwell

this video is sped-up and slightly uncomfortable to watch; you'll see what i mean if you slow the playback speed

@IMSAIGuy

7 ай бұрын

normal speed. what you are hearing is someone talking who did optics for 40 years.

@2o4II112II26o2

6 ай бұрын

Ok thank you very kindly for taking the time to reply; I apologise. Thank you for your contribution via your videos to our understanding of the topics you speak about .. David to @@IMSAIGuy