View Full Version : what happens in a lens


John M. McCloskey
August 29th, 2007, 09:26 AM
Hope its oK to ask this question here. I am looking for some educational video or 3D model or photographs of what is happening inside of a video lens. Would really like to find a moving animation showing what an image goes through from entering lens and everything it goes through up to it being embedded to the tape or disk. Thanks for any help.

Tom Hardwick
August 29th, 2007, 09:41 AM
There's really no such thing as a 'video lens' John. All lenses bring parallel rays at infinity to a focus point at the focal plane. You've held up a simple magnifying glass to focus the sun's rays onto a piece of paper and watched it smoulder - there, you know how a lens works.

Such a simple single element brings with it many distortions, so prime (i e non zoom) lenses are multi-element affairs. A diaphragm is built in so that light levels can be cut down, and elements can move so that images at different distances (not just at infinity as the sun is) can be focused.

Look here for a simple demonstration of optical image stabilisation at work:

http://www.canon.com/bctv/faq/optis.html

tom.

Chris Barcellos
August 29th, 2007, 09:44 AM
Hope its oK to ask this question here. I am looking for some educational video or 3D model or photographs of what is happening inside of a video lens. Would really like to find a moving animation showing what an image goes through from entering lens and everything it goes through up to it being embedded to the tape or disk. Thanks for any help.

Wikipedia is always a good place to start on something like this:

http://en.wikipedia.org/wiki/Camcorders

Also, check out this:

http://electronics.howstuffworks.com/camcorder.htm

John M. McCloskey
August 29th, 2007, 09:51 AM
Thanks for the link Tom. I have tons of articles explaing lens dynamics, I am really trying to find some visual educational tools to better explain what happens in a lens. Looking for a basic 101 of what an image interacts with on its way to being embeded on film, tape, or any other media. THX for the reply

Stelios Christofides
August 29th, 2007, 02:57 PM
John

I think what you want in not what happens to the lens but what happens after the lens.
http://en.wikipedia.org/wiki/Camcorder

Stelios

Steve House
August 29th, 2007, 03:06 PM
Hope its oK to ask this question here. I am looking for some educational video or 3D model or photographs of what is happening inside of a video lens. Would really like to find a moving animation showing what an image goes through from entering lens and everything it goes through up to it being embedded to the tape or disk. Thanks for any help.

I can't think of a specific title but have you checked through AV materials on physics and optics offered by publishers of textbooks and educational courseware? Such video or animations are common fare in high school and college level courses.

John M. McCloskey
August 29th, 2007, 03:29 PM
This link is very similar to what I am looking for

http://members.tripod.com/~Camera_Dave/lens-theory-2.htm

Thanks for all the input, should make explaining much more entertaining. THX