Physics of lenses

I'm currently a university physics student - where can I find some in-depth details on the physics of how these lenses work? I'm doing an optics course and I'm really interested... math knowledge is not an issue, I'm fine with all the math - just need to work through the optics

It'd be nice to know how a prime / simple zoom lens works! I'm guessing changing the position of some of the elements increases the angular magnification through a bigger spacing between lens groups?

don't have anything to contribute, but I am seriously jealous that 1) you understand the information and 2) that you're really interested with it.

I just try to learn how to use my camera, I don't try to go that deep into how it works

1st, good luck with your studies. I majored in physics as well and generally found the studies fun. Of course was was a couple of decades ago...

2nd, look for the Canon publication Lens Work III - especially the last two sections (page 162 and up).

3rd, specific and modern information is likely to be found only in design software, although I did have bookmarked one paper from a student in Colorado.

lbridges wrote in post #7783175
2nd, look for the Canon publication Lens Work III - especially the last two sections (page 162 and up).

http://www.canon-europe.com …ools/ef_lens_wo​rk_iii.asp

Are you kidding? I learned how a prime lens worked in middle school. I'm surprised you wouldn't have covered at least that much yet in a first year college level physics class

motoroller wrote in post #7783016
I'm currently a university physics student - where can I find some in-depth details on the physics of how these lenses work? I'm doing an optics course and I'm really interested... math knowledge is not an issue, I'm fine with all the math - just need to work through the optics

It'd be nice to know how a prime / simple zoom lens works! I'm guessing changing the position of some of the elements increases the angular magnification through a bigger spacing between lens groups?

Tarzanman wrote in post #7783340
Are you kidding? I learned how a prime lens worked in middle school. I'm surprised you wouldn't have covered at least that much yet in a first year college level physics class

A prime lens consists of many different types of elements, some moving for focus etc. You would have learned the absolute basics for a point source or infinite source of a single bi-convex element in middle school.

Not really about lenses, but Edgerton Center at MIT has some really cool classes on high speed photography and you can get lectures notes online.

http://web.mit.edu/Edg​erton/
Course 6.163 lectures notes http://web.mit.edu/6.1​63/www/resources.html

Try the library at your university.

motoroller wrote in post #7783383
A prime lens consists of many different types of elements, some moving for focus etc. You would have learned the absolute basics for a point source or infinite source of a single bi-convex element in middle school.

There are both internal and external focusing in SLR lenses. More modern lenses, particularly zooms, will often focus internally, in which case some lens elements will move.
However, most prime lenses focus by moving all of the elements together in relation to the focal plane(film or sensor), so none of the internal elements move.

In a perfect world, we would only need one glass element for a perfect lens. However, because different colors of light have different dispersion characteristics through glass(they bend by different amounts), the same colors don't focus on exactly the same point. In order to compensate for this, two different types of glass are used: "Crown glass" for convex lens elements, and "Flint glass" for concave elements. These two different types of glass have a different refractive index and different dispersion. When used in combination in a lens, depending on the design, the red and blue light will focus more or less on the same point. This is called an achromatic doublet. In order to correct for green as well, one or more extra low dispersion lens elements can be used, which along with the other two different types of glass, are called apochromatic lenses. The aim is this case, is to focus red, blue AND green on the same point. However, because of the cost, most lenses don't have the low dispersion lenses.

Lens elements are also mostly ground to a spherical shape(the ideal is parabolic), so additional compensation must be designed to reduce this problem. In some cases, some aspherical lens elements are used.

The lens elements must also compensate for optical design. For example, in a EF mount Canon SLR, the distance from mount ot focal plane is more than 40mm. So how do you use a lens with a 20mm focal length, without hitting the mirror?? The lens must be designed to give the same field of view as a 20mm lens, while keeping the rear lens element around 40mm from the focal plane. This type of design is called "Retrofocal". And if you want a long focal length lens to be shorter than its required focal length (e.g. a 400mm lens shorter than 400mm), the you need to use an optical design called "telephoto".

Of course, it's even harder to design a zoom lens to compenstate for the different colors, plus the different optical designs. Telephoto zooms adjust the degree of telephoto optical design within the lens.

Good info

A good read is "The Optics of Photography and Photographic Lenses" by J Traill Taylor.....still available. I've got a few older tomes that are long out of print but may pop up in secondhand bookshops.

Bob

hands on learning

take one apart

SnlpeR wrote in post #7786987
hands on learning

take one apart

haha jk...
i have yet to put this thing back together...
waiting longer and ill forget how it goes back

Which lens is that?!

And how much for it? That'd be one great learning curve!

Actually, I found this on a page that someone posted - http://software.canon-europe.com …_Lens_Work_Book​_10_EN.pdf


It's great for the absolute basics. I'll look out for books and other more technical documents.

its a canon 24-85
it had some mildew on one of the elements
come to find out its the hell to get to the element because its in a group of elements thats stuck together

i had to scrape out the plastic holder and pull this lens out...
now i gotta JB Weld it back and reassemble the whole thing

but man its cool looking at how things work inside a lens