Monday, January 17, 2022

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

Lesson 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.

Sunday, January 9, 2022

AYWMC: Part 1 Technical, Lesson 4: ISO

Lesson 4 in my own words:
  • ISO (International Standards Organisation) - a measure of sensitivity to light
    • 1 of 3 options (along with aperture and shutter speed) to control the amount of light hitting the camera's sensor.
    • Technical aspect: increasing ISO makes it easy to take photos in low light.
    • Creative aspect: none
    • Potential negative aspect: high ISO can degrade the quality of the photo.
  • Changing ISO
    • Auto ISO - lets the camera choose
    • Manual ISO - check camera manual for instructions
  • When to change ISO
    • On manual shutter speed 
      • long shutter speed may require a lower ISO to darken the exposure
      • fast shutter speed may require a higher ISO to lighten the exposure
    • On manual aperture settings 
      • as depth of field increases (due to smaller aperture), more light is needed for proper exposure.
      • increasing ISO is an alternative to lengthening shutter speed, which increases the risk of camera shake.

This week's project:
  • Step 1
    • Learn how to change your ISO manually. 
    • Find out if you have Auto ISO and in which modes it works.
  • Step 2
    • Choose either the aperture or shutter speed exercise from lessons 2 or 3, and experiment with the ISO for each.
    • Don't worry about the quality of the photo (graininess/noise). The purpose of the exercise is to begin to understand ISO through experience.
I decided to try the homework on both aperture and shutter speed. I took these photos at the largest resolution my camera offers (6000 pixels by 4000 pixels), which is way too large to display on this blog. So I resized them to 500 pixels by 333 pixels, to display the entire image. To get a closer look at image quality, I also cropped a 500x333 selection from the original photo.

I started with aperture.

Large aperture (f/5.0) and low ISO (100)

Same photo, clip from original size

Large aperture (f/5.0) and high ISO (25,600)

Same photo, clip from original size

Small aperture (f/32.0) and low ISO (100)

Same photo, clip from original size

Small aperture (f/32.0) and high ISO (25,600)

Same photo, clip from original size

Then I took a second set with different shutter speeds.

Short shutter speed (1/40 sec) and low ISO (100)

Same photo, clip from original size


Short shutter speed (1/40 sec) and high ISO (25600)

Same photo, clip from original size

Long shutter speed (1/4 sec) and low ISO (100)

Same photo, clip from original size

Long shutter speed (1/4 sec) and high ISO (25600)

Same photo, clip from original size

What I learned:
  • I could definitely see the point of the lesson, that photo quality degrades with higher ISOs. 
  • Since I manually controlled only two of the three things that affect exposure (aperture, shutter speed, and ISO), and the camera compensated by automatically adjusting the other one. 
  • That correct exposure is a complex task and will take a lot of practice to master (or at least get half-way decent at.)
  • That my camera does a really good job compensating. (So, I'm not sure I got all the subpoints of the lesson).
    • I won't have to worry much about ISO for any photo I publish on the internet. Graininess can't be seen after resizing them for online use, unless I crop like I did for this exercise.
    • For print photos, I'll have to take more care to avoid grainy pictures.

Thursday, December 30, 2021

AYWMC: Part 1 Technical, Lesson 3: Shutter Speed

Lesson 3 in my own words:

  • Shutter speed - the speed at which the camera's shutter opens and closes.
    • The technical aspect of shutter speed is controlling the amount of light entering the camera and hitting the sensor.
      • slower speed = more light
      • faster speed = less light
    • The creative aspect of shutter speed is controlling the amount of blur in the image.
  • Blur versus camera shake
    • Blur occurs when the subject is moving.
    • Camera shake occurs when the camera is moving.
    • Both indicate a need for a faster shutter speed.
  • If shutter speed is faster than the subject is moving, you can freeze the action.

This week's project:

On shutter priority mode (Tv or time value), in a well lit place (preferably outside), take 2 photos of the same moving subject, one with a short shutter speed and one with a longer shutter speed.

Duck walking, short shutter speed (1/1000 sec.)

Duck walking, longer shutter speed (1/4 sec.)

What I learned:

This was a more challenging lesson than the one on aperture because changing shutter speed changed other things too. 
  1. When adjusting shutter speed on my camera, it affected brightness or darkness (you can see the difference in the above two photos). The longer the shutter speed, the brighter it got. Faster made it darker. I could preview this on the camera's LCD screen. "What you see is what you get" was one of the selling points of a mirrorless camera. Now, I'm curious whether the same is true with a DSLR.
  2. On Tv mode, I chose the shutter speed and the camera chose the aperture and ISO.
  3. I learned first hand about camera shake. With a slow shutter speed, it's difficult to hold the camera still (why a tripod would be useful!) For this lesson's photos, I judged shake vs. blur by the background. If the background was blurred as well as the subject, then I knew it was shake. Contrast the photo below with the photo above to see the difference.
Duck walking, long shutter speed (1/8 sec), and camera shake.

I realize that with just these few lessons, I'm looking at photographs differently. I now look at a photo and think about aperture and shutter speed. Not sure that's a good thing, but it is what it is.

Saturday, December 25, 2021

AYWMC: Part 1 Technical, Lesson 2: Aperture

Lesson 2 in my own words:
  • Aperture - adjustable opening of the camera lens that can be made larger or smaller. 
    • One of three ways the camera controls the amount of light entering the camera and hitting the sensor
    • The technical aspect of aperture is controlling the amount of light
      • larger opening = more light
      • smaller opening = less light
    • The creative aspect of aperture is controlling the depth of field
  • Depth of field - how much of the image is acceptably sharp to the eye
    • a large depth of field needs a small aperture
    • a small depth of field needs a large aperture (eg. a sharp object with blurred background)
  • In the auto and program modes, the camera chooses aperture.
  • In the aperture priority mode (Av or aperture value), the photographer chooses aperture, and the camera chooses the shutter speed.
  • Aperture + shutter speed + ISO create the exposure to take the photograph.
  • Aperture settings are called f-numbers or f-stops.
    • smallest number = largest size
    • largest number = smallest size

This week's project:

1. Find and write down the name of your lens: 15-45mm
2. Find and write down the highest and lowest aperture for your lens: 
  • at 15mm: f3.5 & f22
  • at 45mm: f6.3 & f40
3. Take 2 photos which are exactly the same except for the aperture. Take one photo with your camera's largest aperture, and one with the camera's smallest aperture.

largest aperture

smallest aperture

What I learned:

I now have a basic working knowledge of what aperture is and what it does. What's a little confusing is that the largest aperture has the smallest f-number; kind of counterintuitive. Hmm, how to remember? Well, a completely open aperture looks like a big O (oh) or 0 (zero). So, the f-numbers closest to zero indicate the larger openings. As the aperture gets smaller, the numbers move further away from zero. That may not make sense to anyone else, but it works for me!

Sunday, December 19, 2021

AYWMC: Part 1: Technical, Lesson 1: Intro. to Exposure

Lesson 1 in my own words: 
  • Exposure - the amount of light in a photograph. Overexposed photos appear too light; underexposed photos appear too dark.
  • 3 things control exposure: aperture, shutter speed, and ISO
  • In auto or program mode, the camera is programmed to adjust exposure to an approximate overall tone of 18% gray. This may or may not be correct (or what the photographer wants).
  • Overall tone - the average of all the tones in an image. To assess this, the camera is programmed to interpret color in black and white. From this, it automatically adjusts exposure to equate 18% gray.

This week's project: 

With the camera in auto or program mode, take two photos. For one, fill the camera frame with solid black (paper). For the other, fill the entire camera frame with solid white. Aim for the same lighting for each, with no shadows, highlights, or reflections. 

photo of black posterboard

photo of white posterboard

What I learned: 

The project illustrates the lesson! That the camera will default to a mid-tone gray when dealing with color. Interesting.