Autofocus System Design

Started Aug 15, 2014 | Discussions thread
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Marianne Oelund Veteran Member • Posts: 6,581
Autofocus System Design

This thread will present the stepwise development of a phase-detect autofocus system, using basic optical concepts and ray diagrams. The intent is to lay a solid foundation for the reader, to understand concepts critical to autofocus optics and operation, at a level which is visual, intuitive and readily understandable. There will be some mention of mathematical concepts that apply, but a working knowledge of them is not required in order to follow the discussion and diagrams.

See the following posts for presentations of each step in the development. More posts will be added later, as I have time, and/or in response to questions. The initial posts cover the fundamental optics for the AF system, starting with a single lens, then adding more optics to complete the AF system optical model.

There are many misconceptions associated with AF system behavior, as it is not always intuitive. Some readers may have difficulty accepting the system characteristics described, and ask for supporting references. The best reference I can give, is an optical system that I have sitting on my table right now, configured as detailed in the first few posts: It functions exactly as specified in this thread. I will post some details of that system, and photos of its operation, at a later time (taking photos can be easier than constructing theoretical diagrams, anyhow).

Suffice it to say that this thread will present more than purely theoretical concepts. It is my hope that this will be both fun and educational.

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Qualities possessed by God in infinite proportion: Love, Grace, Power, Righteousness, Wisdom, . . .
Qualities possessed by humans in infinite proportion: Ignorance.
- Marianne

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