DIGITAL PHOTOGRAPHY #101: APERTURE Part 2 of 2
(The fun begins!)
Life is a series of moments that leaves us with memories, both splintered and whole.
If you are just joining us, the PRELUDE & SYLLABUS section is the logical starting point for the series..
Welcome to Digital Photography #101,
by Virtual Studio Photography (VSPHO)
In part 2, we will start using our new knowledge of the aperture to create different visual effects with our pictures.
We left off in APERTURE Part 1 with the range of aperture settings:
The standard f-stops are 1.4, 2.0, 2.8, 4.0, 5.6, 8, 11, 16, 22 and 32.
To be clear, the f-stop of 1.4 means: That for every millimeter of diameter of the aperture, the focal length is 1.4 millimeters long. The actual aperture opening equals 35.7 mm in diameter on a 50mm lens.
The f-stop of 32 means: That for every millimeter of diameter of the aperture, the focal length is 32 millimeters long. The ratio of aperture diameter to focal length is 1:32. The actual aperture opening equals a tiny 1.56 mm in diameter on a 50mm lens.
We've already discussed (in Part 1) that each f-stop represents either twice as much light, or half the light of the pervious f-stop. So most digital cameras also offer the availability of 1/3 or 1/2 f-stop steps in between each full f-stop for additional light control.
Although most lenses will not have this full of a range of f-stops (1.4 to 32), the functionality of the available f-stops will work the same on all lenses. Note that many variable "zoom" lenses only start at f-stop 3.5. We will discuss more in the lens section.
This Nikon/Nikkor 300mm lens starts at f-stop 2.8 becasue of the large front lens. You can get a better/larger view of this lens by clicking twice on the image at the top right of the article.
So we now know that the f-stop regulates the amount of light allowed onto the photo sensor for the exposure.
The second parameter the f-stop regulates is the "Depth of Field."
The "Depth of Field" is the ratio of distances that will be in focus with any given f-stop.
We will explain the logic in another section. But all you need understand is the basics for now.
Don't worry, I'll give you a few examples.
With a large aperture, say 1.4, you will have a very SHORT/SHALLOW Depth of Field. With the 50mm lens, if you are shooting a person at 10 feet away, the depth that would be in focus would only be less than a foot (.68 feet). That is, if your person held their hand in front of themselves with a flower, the flower would be Out of Focus.
In the same picture, if we adjusted all the other settings (we'll cover later) to allow the f-stop of say 22, then the same person at 10 feet away would have a "buffer" of focused area in front and behind of 15 feet, not .68 feet.
The RATIO of the "Depth of Field" distance in front of the subject is about 33% in focus, and the distance behind the subject is the remaining 67% will be in focus.
Let's go with another example, the same shot but at 50 feet away, not 10 feet.
At 50 feet with our 50 mm lens and the f-stop at 1.4, the Depth of Field will increase from the previous .68 feet to approx 18 feet. That's 6 feet in front of your subject that will still be in focus and 12 feet behind your subject that will still be in focus.
On the other end of the f-stop spectrum, with our 50 mm lens and now the f-stop at 22, our Depth of Field goes to approx. 13 feet in front of your subject to infinity in focus behind your subject.
Do not worry about this ratio for now, just be aware that the f-stop affects what is in focus, the Depth of Field.
So one would ask: "Why not always use the smallest aperture (largest number) possible all the time?
I would say that if you are on vacation and want as much as possible in focus all the time, use the smallest aperture (largest number) all the time. Around f-stop 8, is a good aperture to keep most things in focus. Of course, f-stop 11 and 16 are even better. Disposable cameras have an f-stop of 8 or smaller (11 or 16) for that very reason.
But if light is limited, the larger aperture (smaller number) compensates for the low light, but less will be in focus.
Let us also mention, there is real artistic value at times with a very short Depth of Field.
For example, you wish to shoot a beautiful flower from the perfect position, but in the background is a parking lot. If you set the aperture to as large as possible (smallest number), you can turn the parking lot into a beautiful, blurred background while the flower is now a piece of art.
Hold the CNTL key and hit + or - to control the image size.
Click HERE to Enlarge: Then hit the "back arrow" at top left of page to return. If the picture comes up BLANK, just hit the screen REFRESH key, Round Arrow upper left of screen.
We will cover the other settings in relation to the aperture in PHOTOGRAPHY #101: PRELUDE
For now, on your digital camera, set the MODE to the "A" position. That is the Aperture Priority position on your camera. You can now set the camera to stay on any given f-stop. The camera will now automatically set the shutter speed based on the ISO setting that we will cover in the next section.
Just play with getting creative with the aperture!
Take the same picture a few times with changing the aperture between each shot.
We will cover doing this automatically with "bracketing" in a future section.
But next comes the SHUTTER SPEED.
Virtual Studio Photography (VSPHO)
Tags: PHOTOGRAPHY , DIGITAL PHOTOGRAPHY
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