ask tyler: a is for aperture

See what I did there in the title?  Kind of like A is for Apple?  Little play on words?  Not funny? OK Moving On.

Remember when like a year ago, Wendy stated that I was going to start answering a photo question a week and than I was hit with a total mental block every time a contemplated answering a question?  Yah, that was rad.

Well, sorry about that.  I decided to start at the beginning (it is a very good place to start- so what if I was raised on musicals?)

Photography is, at its core, about capturing a moment of light.  You start with a light proof box of one sort or another.  You then allow light to enter onto the sensor, or the film, for a moment to make the exposure.  

There are three main ingredients to this recipe.  Shutter Speed, ISO and Aperture.  But, only one begins with “A” and would permit me my stupid introductory pun.

The aperture is, as it sounds like, the opening.

Dslr lenses have blades that open and close to adjust the aperture.  An f-stop is a measurement of how wide the aperture is.  As the F-stop gets a higher number the aperture, non-intuitively, gets smaller.  (That is because the f-stop is a fraction, but let's not get too geeky right off.)  So moving from F/1.4 to F/2 to F/2.8 to F/4 to F/5.6 to F/8 is really a decrease in the size of the aperture.  

Moving down one full f-stop doubles the amount of light that the lens lets in.   So, F/1.4 lets in twice as much light as F/2 and four times as much light as F/2.8.  You will sometimes hear a lens with a large maximum aperture referred to as "fast".  This is because it lets in more light at its maximum aperture, which allows a faster shutter speed to be used.

If you want to shoot pictures at an indoor gym and freeze motion, a fast lens is very handy.  If you shoot with an f/4 lens and the available light allows for a 1/30th of a second shutter speed, then an F/1.4 lens would allow you to shoot at 1/250th of a second for the same exposure which will make it a lot easier to freeze motion.  

But this is not why I love fast lenses.  The main reason that I love my 50mm 1.2 lens is another byproduct of a wide aperture.  That is that it reduces the depth of field.  (It is not the only factor, but more on that later in another post*). The depth of field is the area that appears to be in focus in a picture.  A deep depth of field makes everything appear in focus.  A shallow depth of field makes almost nothing appear in focus.  And that is what I love.

*unless someone really wants a post on depth of field, i am planning on sweeping this promise under the rug.

The following photos were shot wide open at 1.2

20091211-IMG_3542.jpg
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BLUE LILY | Lifestyle Photographer | Salt Lake City, Utah