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Photo U – A Journey into Photography Session 2: Understanding ExposureAlex Santiago
Agenda
What is exposure
Elements of Exposure
Exposure Triangle
Depth Of Field (DOF) Explained
What is Exposure?
Exposure is the process of capturing light in a single shutter cycle to produce an image
Exposure that achieves the effect the photographer intended is “correct” exposure
Exposure is Filling a Bucket…
Think of exposure as filling a bucket with water
Things to consider: Water flow Time to fill the bucket Size of hose (wide/thin) Size of bucket (S/L)
Elements of Exposure
Four Elements of Exposure: Light Aperture Shutter Speed ISO
Each element is crucial in the process to create a photograph
Each element may be used in creative ways
Elements of Exposure: Light
The most important of the elements
Light creates shadows, highlights, textures, accents, moods, emotions, and other enhancing effects on a scene/photo
Finding good light is a skill that comes with experience and a LOT of trial and error
Elements of Exposure: Aperture
Controls the amount of light allowed into the lens
Adjustable and may be made to be larger or smaller
Controls depth of field (DOF)
Elements of Exposure: Aperture – How it works…
Elements of Exposure: Aperture – How it works…
Elements of Exposure: Aperture – How it works…
Elements of Exposure: Shutter Speed
The shutter is a curtain inside the camera that opens for a specified duration of time to expose the sensor/film to light
That duration of time is Shutter Speed
Shutter Speed can be used for effects creation in photographs
Elements of Exposure: Shutter Speed
Shutter speed is used for the following reasons: Determine safe hand
hold speed Stopping action (fast
shutter) Blurring action (slow
shutter)
Elements of Exposure: Shutter Speed – How it works…
Safe hand hold shutter speed to prevent blurry images: Rule of thumb is to
always use a shutter speed equal to the focal length Example:
Lens = 50mmSS: 1/50 sLens: 100mmSS: 1/125mm
Elements of Exposure: Shutter Speed – How it works…
Shutter Speed at 2 seconds
Elements of Exposure: Shutter Speed – How it works…
Shutter Speed at 1 second
Elements of Exposure: Shutter Speed – How it works…
Elements of Exposure: ISO
ISO is the speed with which your digital camera sensor responds to light
Lower ISO setting will require longer exposure time to create an image
Higher ISO setting will capture the same scene with a shorter exposure time
Elements of Exposure: ISO – How it works…
Elements of Exposure: ISO – How it works…
Elements of Exposure: ISO – How it works…
The Exposure Triangle
The Exposure Triangle is a visual representation of the three ingredients needed for a properly exposed image
The relationship between shutter speed, aperture, and ISO is at the heart of all photography
Understanding the exposure triangle will assist you in creating a properly exposed image
Exposure Triangle: Understanding Stops
Aperture, Shutter Speed, and ISO are adjustable
Shutter speed adjustments are done in seconds or fraction of a second
Aperture adjustments are done in f/stops which translate to the size of the lens divided by the aperture Lens size/fstop=aperture
size
ISO Stop Chart f/stops Chart Shutter Speed100 1 1/8000200 1.4 1/4000400 2 1/2000800 2.8 1/10001600 4 1/5003200 5.6 1/2506400 8 1/125
12800 11 1/6016 1/3022 1/1532 1/8
1/41/21"2"4"8"15"30"
Sensitiv
ity
Apertu
re S
ize
smallest
Largest
Fast
Slow
Shutte
r Speed
in S
eco
nds
Slow
Fast
Full Stops Chart
Exposure Triangle: Balancing the Elements of Exposure
When we choose an appropriate combination of shutter speed and aperture size that works, it will not be the only combination
There are multiple correct exposure combination for any scene
The best combination is that which provide the effect intended for the image
Exposure Triangle: Balancing the Elements of Exposure
Let’s look at an example: Aperture: f/11 Shutter Speed: 1/250” ISO: 100
There are several reasons not to use this settings
Determine the rest of the correct exposure values
Hands on Exercise
Depth Of Field (DOF) Explained – What is DOF?
A camera can only focus its lens at a single point
The area in front and behind the focus point that appears to be sharp is the DOF
DOF has an aesthetic and technical impact on an image
DOF enables you to direct viewers to the focal point of an image
Depth Of Field (DOF) Explained – Shallow DOF
Shallow DOF will help you isolate your subject in an image
The objective is to have the subject in focus while having the foreground/background out of focus
Depth Of Field (DOF) Explained – Ingredients for Shallow DOF
Ingredients for shallow DOF Large Aperture Size
(depending on the lens 3.5, 2.8, etc.)
Long Focal Length (70-200 mm, 300mm, etc.)
Lens closer to your subject
Depth Of Field (DOF) Explained – Deep DOF
Deep DOF brings a majority (if not all) of your photograph into sharp focus
Crucial for beautiful landscape images
Require longer exposure time
Depth Of Field (DOF) Explained – Ingredients for Deep DOF
Ingredients for Deep DOF Smaller Aperture Size
(depending on the lens 8,11, 16, etc.)
Short Focal Length (10-24mm, 16-24mm, etc.)
Lens further away from your subject
Questions?