AYWMC: Part 1 Technical, Lesson 5: The Exposure Triangle

This post is part of a series entitled A Year With My Camera.  

 

Lesson 1.5 in my own words:

• Review
• On the auto modes (auto, program, aperture, and shutter priority), the camera determines exposure.
• The camera chooses the aperture, shutter speed, and ISO to produce an equivalent to an 18% mid-tone gray image.
• The camera isn't programmed for creative effects, and therefore never chooses extremes in aperture, shutter speed, and ISO.
• The exposure triangle
• Aperture, shutter speed, and ISO are the three corners of the triangle.
• If one goes up, the other two must go down to compensate and correct exposure.
• The camera does the compensating in any of the auto modes.
• Manual mode gives the photographer complete control of the camera.
• Understanding Stops
• Stops are measurements of the amount of light the camera lets in via aperture, shutter speed, and ISO. 
• Each stop lets in the same amount of light. Example: 1 stop on the aperture scale corresponds to 1 stop on the shutter speed scale.
• Each change in stop doubles or halves the amount of light.
• The photographer can choose full, half, or third stops.
• Applying stops to the exposure triangle 
• Example - If aperture is increased by two stops, then either shutter speed or ISO must be decreased by two stops. Or, both must be decreased by one stop each.

This week's project:

• Practice adjusting exposure settings but keep the overall exposure the same by applying the principles of the exposure triangle.
• Start with aperture priority mode.
• Choose a mid-range full aperture stop and take a photo
• Write down the three settings
• The aperture stop you chose
• The shutter speed and ISO the camera chose
• Change to manual mode
• Dial in the three settings you copied from the first photo
• Change the aperture stop to the next full wider aperture stop.
• Change the shutter speed one stop in the opposite direction (faster).
• Take a second photo. Both photos should have the same exposure.

Av mode: I chose f/8.0. Camera chose 1/60th sec. and ISO 100

Manual mode: f/7.1, 1/80th sec, ISO 100

• Try the same exercise with shutter speed.
• Change your camera to shutter priority.
• Choose a shutter speed between 1/60 & 1/250, and take a photo
• Write down the three settings
• The shutter speed you chose
• The aperture and ISO the camera chose
• Change to manual mode
• Dial in the three settings you copied from the photo.
• Change the shutter speed two full stops.
• Change aperture and ISO one stop each in the opposite direction.
• Take a second photo. Both photos should have the same exposure.

Tv mode: I chose 1/100th sec. Camera chose f/16 and ISO 100.

Manual mode: 1/160th, f/18, and ISO 200.

What I learned:

• That this was hard! Because:
• None of the numbers are intuitive yet, so "opposite" stumped me, as does "higher" and "lower.
• I haven't memorized full versus half or third stops, so I wasn't sure I was following the assignment by simply turning the dial.
• (I'm not entirely sure I adjusted the settings correctly.)
• But I did learn some things:
• How to adjust aperture, shutter speed, and ISO on manual mode
• How the exposure triangle works. (In other words, I got the lesson!)
• I'm also learning that I need a lot more practice with each lesson, so that I'm not having to stop and think for every adjustment.