Some questions about lens design diagrams and a type of element

bdery · 05-23-2019, 10:18 AM - **1 Like**

Originally posted by Ropuchy

If the element is two parts, is it only counted as a single element because it forms a biconvex element?

If it's the same material, but simply manufactured in two parts then glued together, from an optical point of view it's one element. If it was me, I'd draw it like on your image. If it was a doublet (a group made of two types of glass sharing an interface) I'd draw the two elements separately.

Ropuchy · 05-23-2019, 12:57 PM

Originally posted by bdery

If it's the same material, but simply manufactured in two parts then glued together, from an optical point of view it's one element. If it was me, I'd draw it like on your image. If it was a doublet (a group made of two types of glass sharing an interface) I'd draw the two elements separately.

Alright, thanks for clarifying!

**Bob 256** · 05-23-2019, 03:36 PM - **1 Like**

I've seen some lens designs where there's a section of "tubing" with a lens element tacked on each end. That's another possibility for that circled "element" - could be a couple of air spaced elements.

There are a lot of good introductory lens design books available. Check Amazon and search for "lens design", "optical lenses", and "amateur lens making" (Google also). Most lens design falls under physics, so you might check your public library if it's a large one, in the physics section. Wikipedia is another source (see below), and companies that make lenses like Edmunds.

https://en.wikipedia.org/wiki/Optical_lens_design

https://en.wikipedia.org/wiki/Photographic_lens_design

https://www.edmundoptics.com/resources/application-notes/optics/understandin...ens-geometries

https://www.sciencedirect.com/book/9780123743015/lens-design-fundamentals

bdery · 05-24-2019, 04:48 AM - **1 Like**

Originally posted by Bob 256

could be a couple of air spaced elements

In that case, if it was me I'd definitely draw the elements as separate

Originally posted by Bob 256

There are a lot of good introductory lens design books available. Check Amazon and search for "lens design", "optical lenses", and "amateur lens making" (Google also). Most lens design falls under physics, so you might check your public library if it's a large one, in the physics section. Wikipedia is another source (see below), and companies that make lenses like Edmunds.

Learning about optical design in broad terms can be done with some success via wikipedia et al. If someone wants to go deeper, there are some introductory physics books, however they all require some ease with maths. The book "Optics" by Hecht is far from the best, but it's a good one for introductions, with minimal maths and a lot of text.

**Bob 256** · 05-24-2019, 08:56 AM - **1 Like**

Originally posted by bdery

In that case, if it was me I'd definitely draw the elements as separate

.

Totally agree, but some lensmakers (Pentax) take shortcuts or sometimes don't want to give away all the secrets. I believe, the lens I referred to showed a similar abbreviated "lens element" on the box it came in. Not a full-blown lens diagram, but good enough for the sales department

Ropuchy · 05-24-2019, 11:18 AM

Originally posted by Bob 256

I've seen some lens designs where there's a section of "tubing" with a lens element tacked on each end. That's another possibility for that circled "element" - could be a couple of air spaced elements.

There are a lot of good introductory lens design books available. Check Amazon and search for "lens design", "optical lenses", and "amateur lens making" (Google also). Most lens design falls under physics, so you might check your public library if it's a large one, in the physics section. Wikipedia is another source (see below), and companies that make lenses like Edmunds.

Optical lens design - Wikipedia

https://en.wikipedia.org/wiki/Photographic_lens_designhttp://

https://www.edmundoptics.com/resources/application-notes/optics/understandin...etries/http://

Lens Design Fundamentals | ScienceDirect

Thanks for the links! I'll look into them when I've got some time, the Edmunds one looks interesting.

Also, it looks like 'http://' was added onto the ends of the two middle links, so they won't work correctly when you click on them.

---------- Post added 05-24-19 at 11:22 AM ----------

Originally posted by bdery

In that case, if it was me I'd definitely draw the elements as separate

Learning about optical design in broad terms can be done with some success via wikipedia et al. If someone wants to go deeper, there are some introductory physics books, however they all require some ease with maths. The book "Optics" by Hecht is far from the best, but it's a good one for introductions, with minimal maths and a lot of text.

I actually like maths, just not the stuff they teach in school unfortunately. Do you know of any more technical and to-the-point sorts of books with less reading, or would 'Optics' by Hecht still be a good place to start?

**Bob 256** · 05-25-2019, 12:53 PM - **1 Like**

Originally posted by Ropuchy

Thanks for the links! I'll look into them when I've got some time, the Edmunds one looks interesting.

Also, it looks like 'http://' was added onto the ends of the two middle links, so they won't work correctly when you click on them.[COLOR="Silver"]

That's really strange - I fixed those in my original posting so they should work now. Not sure how that happened.

bdery · 05-27-2019, 05:08 AM - **1 Like**

Originally posted by Ropuchy

I actually like maths, just not the stuff they teach in school unfortunately. Do you know of any more technical and to-the-point sorts of books with less reading, or would 'Optics' by Hecht still be a good place to start?

Depends on your math level... Liking math and having completed college-level math classes are two different things. If you want to understand the math underlying the physics, you need to be comfortable with differential equations, solving special functions like Bessel functions (that one is more for fiber optics, but still), using matrices, calculus, etc. Not saying you can't, I really have no idea, but I do know that for a lot of people, what I just wrote is gibberish.

Hecht strikes a good balance. There's an older book, probably called "optics" also, by Mueller. fcuses on matrices a lot (Jones matrices, in fact) so might be easier for some. Introduction to optical design is pretty good, but quite technical, I wouldn't use it as a starting point. There's also the user guide to the Oslo optical design software, it's VERY technical but that user guide is in fact an optical design textbook. A college-level introduction to optics might be "Field and wave electromagnetic" by Cheng, quite good, gives you what you need to know to start learning bout optical design, but of course quite a lot of math.

Ropuchy · 05-27-2019, 06:23 PM

Originally posted by Bob 256

That's really strange - I fixed those in my original posting so they should work now. Not sure how that happened.

No worries, I was still able to get them to work. Thanks for fixing them!

---------- Post added 05-27-19 at 06:29 PM ----------

Originally posted by bdery

Depends on your math level... Liking math and having completed college-level math classes are two different things. If you want to understand the math underlying the physics, you need to be comfortable with differential equations, solving special functions like Bessel functions (that one is more for fiber optics, but still), using matrices, calculus, etc. Not saying you can't, I really have no idea, but I do know that for a lot of people, what I just wrote is gibberish.

Hecht strikes a good balance. There's an older book, probably called "optics" also, by Mueller. fcuses on matrices a lot (Jones matrices, in fact) so might be easier for some. Introduction to optical design is pretty good, but quite technical, I wouldn't use it as a starting point. There's also the user guide to the Oslo optical design software, it's VERY technical but that user guide is in fact an optical design textbook. A college-level introduction to optics might be "Field and wave electromagnetic" by Cheng, quite good, gives you what you need to know to start learning bout optical design, but of course quite a lot of math.

Well, I haven't gone to college yet, so that doesn't bode well.
I'll have to look at your suggestions and see what suits me. Thank you for all the input and suggestions!

**Bob 256** · 05-28-2019, 12:53 PM - **1 Like**

Originally posted by Ropuchy

No worries, I was still able to get them to work. Thanks for fixing them!

---------- Post added 05-27-19 at 06:29 PM ----------

Well, I haven't gone to college yet, so that doesn't bode well.
I'll have to look at your suggestions and see what suits me. Thank you for all the input and suggestions!

Most lens work deals with trigonometry so hope you picked that up somewhere along the way. You'll see a lot of sines, cosines, and tangents popping up in formulas that describe how lenses bend light. Also, there are a number of programs that deal with lens design which do a lot of the number crunching work, and you might be interested in getting something simple there to help you see what's going on (they show light paths on-screen). I think there are a few on-line sites that are interactive that way but I can't remember where I came across them.

Ropuchy · 05-28-2019, 02:59 PM

Originally posted by Bob 256

Most lens work deals with trigonometry so hope you picked that up somewhere along the way. You'll see a lot of sines, cosines, and tangents popping up in formulas that describe how lenses bend light. Also, there are a number of programs that deal with lens design which do a lot of the number crunching work, and you might be interested in getting something simple there to help you see what's going on (they show light paths on-screen). I think there are a few on-line sites that are interactive that way but I can't remember where I came across them.

Yep, at least I know how to do trigonometry.
I'll look into the lens design programs, and see if I can find a site similar to what you describe. Thanks!

**Bob 256** · 05-28-2019, 07:56 PM

Originally posted by Ropuchy

Yep, at least I know how to do trigonometry.
I'll look into the lens design programs, and see if I can find a site similar to what you describe. Thanks!

Here's one site I found that's a lot of fun. You can set up simple optical systems and see how they affect light rays while you make adjustments to the various parameters.

https://ricktu288.github.io/ray-optics/simulator/

It fairly intuitive to use and is better than buying expensive software until you get to that really serious point.

Ropuchy · 05-28-2019, 08:17 PM

Originally posted by Bob 256

Here's one site I found that's a lot of fun. You can set up simple optical systems and see how they affect light rays while you make adjustments to the various parameters.

Ray Optics Simulation

It fairly intuitive to use and is better than buying expensive software until you get to that really serious point.

Thank you for tracking that down for me!
I'll mess around with it a bit, maybe try to recreate some of my lenses.

05-23-2019, 03:36 PM - 1 Like	#18
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	I've seen some lens designs where there's a section of "tubing" with a lens element tacked on each end. That's another possibility for that circled "element" - could be a couple of air spaced elements. There are a lot of good introductory lens design books available. Check Amazon and search for "lens design", "optical lenses", and "amateur lens making" (Google also). Most lens design falls under physics, so you might check your public library if it's a large one, in the physics section. Wikipedia is another source (see below), and companies that make lenses like Edmunds. https://en.wikipedia.org/wiki/Optical_lens_design https://en.wikipedia.org/wiki/Photographic_lens_design https://www.edmundoptics.com/resources/application-notes/optics/understandin...ens-geometries https://www.sciencedirect.com/book/9780123743015/lens-design-fundamentals Last edited by Bob 256; 05-25-2019 at 12:52 PM.

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05-23-2019, 10:18 AM - 1 Like	#16
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,357	Originally posted by Ropuchy If the element is two parts, is it only counted as a single element because it forms a biconvex element? If it's the same material, but simply manufactured in two parts then glued together, from an optical point of view it's one element. If it was me, I'd draw it like on your image. If it was a doublet (a group made of two types of glass sharing an interface) I'd draw the two elements separately.

05-23-2019, 12:57 PM	#17
Ropuchy Senior Member Join Date: Jul 2018 Photos: Albums Posts: 207 Original Poster	Originally posted by bdery If it's the same material, but simply manufactured in two parts then glued together, from an optical point of view it's one element. If it was me, I'd draw it like on your image. If it was a doublet (a group made of two types of glass sharing an interface) I'd draw the two elements separately. Alright, thanks for clarifying!

05-24-2019, 04:48 AM - 1 Like	#19
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,357	Originally posted by Bob 256 could be a couple of air spaced elements In that case, if it was me I'd definitely draw the elements as separate Originally posted by Bob 256 There are a lot of good introductory lens design books available. Check Amazon and search for "lens design", "optical lenses", and "amateur lens making" (Google also). Most lens design falls under physics, so you might check your public library if it's a large one, in the physics section. Wikipedia is another source (see below), and companies that make lenses like Edmunds. Learning about optical design in broad terms can be done with some success via wikipedia et al. If someone wants to go deeper, there are some introductory physics books, however they all require some ease with maths. The book "Optics" by Hecht is far from the best, but it's a good one for introductions, with minimal maths and a lot of text.

05-24-2019, 08:56 AM - 1 Like	#20
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	Originally posted by bdery In that case, if it was me I'd definitely draw the elements as separate . Totally agree, but some lensmakers (Pentax) take shortcuts or sometimes don't want to give away all the secrets. I believe, the lens I referred to showed a similar abbreviated "lens element" on the box it came in. Not a full-blown lens diagram, but good enough for the sales department

05-24-2019, 11:18 AM	#21
Ropuchy Senior Member Join Date: Jul 2018 Photos: Albums Posts: 207 Original Poster	Originally posted by Bob 256 I've seen some lens designs where there's a section of "tubing" with a lens element tacked on each end. That's another possibility for that circled "element" - could be a couple of air spaced elements. There are a lot of good introductory lens design books available. Check Amazon and search for "lens design", "optical lenses", and "amateur lens making" (Google also). Most lens design falls under physics, so you might check your public library if it's a large one, in the physics section. Wikipedia is another source (see below), and companies that make lenses like Edmunds. Optical lens design - Wikipedia https://en.wikipedia.org/wiki/Photographic_lens_designhttp:// https://www.edmundoptics.com/resources/application-notes/optics/understandin...etries/http:// Lens Design Fundamentals \| ScienceDirect Thanks for the links! I'll look into them when I've got some time, the Edmunds one looks interesting. Also, it looks like 'http://' was added onto the ends of the two middle links, so they won't work correctly when you click on them. ---------- Post added 05-24-19 at 11:22 AM ---------- Originally posted by bdery In that case, if it was me I'd definitely draw the elements as separate Learning about optical design in broad terms can be done with some success via wikipedia et al. If someone wants to go deeper, there are some introductory physics books, however they all require some ease with maths. The book "Optics" by Hecht is far from the best, but it's a good one for introductions, with minimal maths and a lot of text. I actually like maths, just not the stuff they teach in school unfortunately. Do you know of any more technical and to-the-point sorts of books with less reading, or would 'Optics' by Hecht still be a good place to start?

05-25-2019, 12:53 PM - 1 Like	#22
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	Originally posted by Ropuchy Thanks for the links! I'll look into them when I've got some time, the Edmunds one looks interesting. Also, it looks like 'http://' was added onto the ends of the two middle links, so they won't work correctly when you click on them.[COLOR="Silver"] That's really strange - I fixed those in my original posting so they should work now. Not sure how that happened.

05-27-2019, 05:08 AM - 1 Like	#23
bdery Pentaxian Join Date: Mar 2008 Location: Quebec city, Canada Photos: Gallery Posts: 9,357	Originally posted by Ropuchy I actually like maths, just not the stuff they teach in school unfortunately. Do you know of any more technical and to-the-point sorts of books with less reading, or would 'Optics' by Hecht still be a good place to start? Depends on your math level... Liking math and having completed college-level math classes are two different things. If you want to understand the math underlying the physics, you need to be comfortable with differential equations, solving special functions like Bessel functions (that one is more for fiber optics, but still), using matrices, calculus, etc. Not saying you can't, I really have no idea, but I do know that for a lot of people, what I just wrote is gibberish. Hecht strikes a good balance. There's an older book, probably called "optics" also, by Mueller. fcuses on matrices a lot (Jones matrices, in fact) so might be easier for some. Introduction to optical design is pretty good, but quite technical, I wouldn't use it as a starting point. There's also the user guide to the Oslo optical design software, it's VERY technical but that user guide is in fact an optical design textbook. A college-level introduction to optics might be "Field and wave electromagnetic" by Cheng, quite good, gives you what you need to know to start learning bout optical design, but of course quite a lot of math.

05-27-2019, 06:23 PM	#24
Ropuchy Senior Member Join Date: Jul 2018 Photos: Albums Posts: 207 Original Poster	Originally posted by Bob 256 That's really strange - I fixed those in my original posting so they should work now. Not sure how that happened. No worries, I was still able to get them to work. Thanks for fixing them! ---------- Post added 05-27-19 at 06:29 PM ---------- Originally posted by bdery Depends on your math level... Liking math and having completed college-level math classes are two different things. If you want to understand the math underlying the physics, you need to be comfortable with differential equations, solving special functions like Bessel functions (that one is more for fiber optics, but still), using matrices, calculus, etc. Not saying you can't, I really have no idea, but I do know that for a lot of people, what I just wrote is gibberish. Hecht strikes a good balance. There's an older book, probably called "optics" also, by Mueller. fcuses on matrices a lot (Jones matrices, in fact) so might be easier for some. Introduction to optical design is pretty good, but quite technical, I wouldn't use it as a starting point. There's also the user guide to the Oslo optical design software, it's VERY technical but that user guide is in fact an optical design textbook. A college-level introduction to optics might be "Field and wave electromagnetic" by Cheng, quite good, gives you what you need to know to start learning bout optical design, but of course quite a lot of math. Well, I haven't gone to college yet, so that doesn't bode well. I'll have to look at your suggestions and see what suits me. Thank you for all the input and suggestions!

05-28-2019, 12:53 PM - 1 Like	#25
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	Originally posted by Ropuchy No worries, I was still able to get them to work. Thanks for fixing them! ---------- Post added 05-27-19 at 06:29 PM ---------- Well, I haven't gone to college yet, so that doesn't bode well. I'll have to look at your suggestions and see what suits me. Thank you for all the input and suggestions! Most lens work deals with trigonometry so hope you picked that up somewhere along the way. You'll see a lot of sines, cosines, and tangents popping up in formulas that describe how lenses bend light. Also, there are a number of programs that deal with lens design which do a lot of the number crunching work, and you might be interested in getting something simple there to help you see what's going on (they show light paths on-screen). I think there are a few on-line sites that are interactive that way but I can't remember where I came across them.

05-28-2019, 02:59 PM	#26
Ropuchy Senior Member Join Date: Jul 2018 Photos: Albums Posts: 207 Original Poster	Originally posted by Bob 256 Most lens work deals with trigonometry so hope you picked that up somewhere along the way. You'll see a lot of sines, cosines, and tangents popping up in formulas that describe how lenses bend light. Also, there are a number of programs that deal with lens design which do a lot of the number crunching work, and you might be interested in getting something simple there to help you see what's going on (they show light paths on-screen). I think there are a few on-line sites that are interactive that way but I can't remember where I came across them. Yep, at least I know how to do trigonometry. I'll look into the lens design programs, and see if I can find a site similar to what you describe. Thanks!

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05-28-2019, 07:56 PM	#27
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,375	Originally posted by Ropuchy Yep, at least I know how to do trigonometry. I'll look into the lens design programs, and see if I can find a site similar to what you describe. Thanks! Here's one site I found that's a lot of fun. You can set up simple optical systems and see how they affect light rays while you make adjustments to the various parameters. https://ricktu288.github.io/ray-optics/simulator/ It fairly intuitive to use and is better than buying expensive software until you get to that really serious point.

05-28-2019, 08:17 PM	#28
Ropuchy Senior Member Join Date: Jul 2018 Photos: Albums Posts: 207 Original Poster	Originally posted by Bob 256 Here's one site I found that's a lot of fun. You can set up simple optical systems and see how they affect light rays while you make adjustments to the various parameters. Ray Optics Simulation It fairly intuitive to use and is better than buying expensive software until you get to that really serious point. Thank you for tracking that down for me! I'll mess around with it a bit, maybe try to recreate some of my lenses.