Photograph of an iris diaphragm by Shieldforyoureyes Dave Fischer
Diaphragm. What are the meanings of this word? Is it a name of a vital organ? Or is it the name of a structure in the lens of a camera that allows light to pass through? It just happens to be both. Some of us may be more familiar with just one meaning of the word “diaphragm.” For me, “diaphragm” has only generated images of the sheet of internal muscle I once saw in a dissection. However, through research and the power of Internet, I have discovered the diaphragm of photography. It is simply a thin structure on the lens of a camera that controls the amount of exposure by adjusting the aperture (opening) at its center. Comprised of six or seven metal blades, the diaphragm adjusts to allow the appropriate amount of light to pass through. Needless to say, the diaphragm is a key component in photography just like the diaphragm in our bodies is a vital part of the human anatomy. In most modern cameras, the adjustable diaphragm is known as an iris diaphragm (photography is full of anatomy terms), which I think is appropriately named for the iris in an eye performs the function. After reading all these articles on photography, I feel pleasantly satisfied with my new knowledge. Now, when someone mentions diaphragm to me, I can picture a cleverly designed mechanism instead of innards. I am very grateful for that thought. Hopefully, the next time you pick up a camera and someone comments on the diaphragm inside the lens, you will know exactly what that person is referring to (and it is not an organ).
For further reading:
http://en.wikipedia.org/wiki/Diaphragm_(optics)
http://www.mir.com.my/rb/photography/glossary/terms_d.htm
