#755 Why is a Camera Lens so Complicated?

Episode 755
A camera lens has many lens elements (pieces of glass). Why? There are many reasons. I try to give some insight by explaining one, field curvature.
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[daltonsimmerman]

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.

[cameraprepper]

Yes, Lenses can be very complicated to design, on one of my many visits to the old Hasselblad Factory, I was told that the Zeiss Biogon 38mm 4.5 took a long time to design and calculate, the amount of A4 papers used for calculation was a stack of one meter high ! I had the Zeiss Mutar 2x teleconverter, after I told the folks at Hasselblad how good it was on the Zeiss Planar 110mm 2.0, they got very interested and wanted to learn more, later I was told that Hasselblad had bought a computer from Canada to calculate Lenses. Today all Lens makers use computer software to calculate Lenses, and Lenses today outperform all older Lenses.

[AntPDC]

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.

[electronicengineer]

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

[ImageNation]

Clicked on the video thinking that this is the start to my journey of making the most compact 1.4 primes to be ever made. I’m just gonna stop while I’m behind.

[PowderMill]

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

[sacundim]

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.

[billpowell]

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

[segercliffhanger]

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.

[jdmccorful]

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

[marcinp.]

"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".

[Malmsteen]

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

[perraudindenis]

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

[danielalt]

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

[healinghub]

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

[eengeeoo]

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

[ronjones]

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

[akashpatra]

Great work Sir ! there is so much to learn. Gone through your channel, quite inspirational, started really loving what you're doing. Thank you so much.

[gerryhardman]

Enjoy this video because I’ve always been fascinated by optics. And it is definitely a mathematical situation. Zeiss took the triplet and turned it into the Tessar, which has certainly stood the test of time as well. Thank you for sharing your thoughts here because it is truly a fascinating video. I look forward to seeing more of these and sharing your knowledge with us layman. In order to get a flat image the curvature of one lens has to be similar to the other to cancel out the curvature of the other lens. That’s why lenses became symmetrical to cancel the curvature of the other lenses. The hologon lens by Zeiss is a good example of this like two opposing marbles cut in half. The Japanese did the same as you, cut the old lenses in half and reverse engineered them and actually eventually made improvements on the Planar and Zenitar designs which many of their lenses (Nikon) are designed after.Regards Gerry

[lmamakos]

I have an Astro-Physics apochromatic triplet, with the 3 lens elements in contact with each other and oil spaced to reduce internal reflections, and improve transmission. I love this thing! For as much as it costs, the field flattener accessory comes with quite a breathtaking price tag; but it was intended for medium format film photography at the focal plane. Fortunately, at the time I acquired it, only APS-C sized CCD devices were practical (affordable!) and the part of the focal plane I was using was "flat enough".

Later I move to using a Riccardi-Honders astrograph, an f/3.8 optical system and quite a novel design. You might mistake it for a Schmidt-Cassagrain but it's actually more like a folded refractor with a rear silvered lens, and more importantly, I believe all spherical lens figures. And a nice, large and wide flat focal plane! Only suitable for astrophotography, but that's the problem I had. Never had an eyepiece in it. I asked the designer of that telescope why he didn't use carbon fiber or some other material with low coefficient of expansion due to temperature for the tube assembly, rather than aluminum? That was a deliberate choice, the dimensional change of the tube due to temperature offset the changes in the optical elements as they also cooled down. There is quite a bit of "art" to go along with the science. Difference between theory and practice and all that stuff you learn the hard way.

Optics are cool! Really nice optics are very cool and expensive! And definitely one of those fields where there's no single "best" tool/design. It's always a tradeoff over a bunch of factors, including $$$ it seems.