DIS Image Acquisition & Capture 3 — Questions and Answers
Question 1: In a RAW file workflow, which step converts linear light data captured by the sensor into a perceptually uniform image?
- Demosaicing
- Gamma encoding / tone curve application (Correct answer)
- Noise reduction
- Sharpening
Correct answer: Gamma encoding / tone curve application
Gamma encoding (e.g., applying a gamma of ~2.2) redistributes linear sensor data so that midtone gradations appear visually smooth to human perception.
Question 2: A lens's 'maximum magnification ratio' of 1:1 means:
- The subject appears half its actual size on the sensor
- The subject is reproduced at life-size on the sensor (Correct answer)
- The lens doubles the apparent focal length
- The depth of field is maximized
Correct answer: The subject is reproduced at life-size on the sensor
A 1:1 magnification ratio means the image of the subject projected onto the sensor is the same physical size as the subject itself.
Question 3: What is 'pixel binning' used for in digital cameras?
- Deleting unwanted pixels from an image
- Combining adjacent pixels to improve low-light sensitivity at reduced resolution (Correct answer)
- Sharpening fine details by isolating individual pixels
- Sorting pixels by color during demosaicing
Correct answer: Combining adjacent pixels to improve low-light sensitivity at reduced resolution
Pixel binning groups neighboring photosites and sums or averages their signals, boosting effective sensitivity while reducing resolution and noise.
Question 4: When using a polarizing filter for outdoor photography, maximum polarization effect is achieved when the camera is pointed:
- Directly toward the sun
- At a 90-degree angle to the sun (Correct answer)
- Away from the sun (backlit scene)
- At a 45-degree angle to the sun
Correct answer: At a 90-degree angle to the sun
A linear or circular polarizing filter has maximum effect when the subject is at approximately 90° to the sun, cutting reflected glare and deepening sky blues.
Question 5: HDR (High Dynamic Range) image capture typically involves:
- Using a single long exposure at a fixed ISO
- Merging multiple exposures taken at different shutter speeds or exposure values (Correct answer)
- Increasing contrast in post-processing using a single image
- Shooting at maximum ISO to capture shadow detail
Correct answer: Merging multiple exposures taken at different shutter speeds or exposure values
HDR merges bracketed exposures—typically 3 to 7 frames at different EVs—to retain detail in both shadows and highlights beyond a single exposure's range.
Question 6: Which sensor characteristic is most directly responsible for the appearance of color fringing (purple or green) along high-contrast edges?
- Thermal noise
- Chromatic aberration and lateral CA in the lens (Correct answer)
- ISO amplification
- Bayer pattern interpolation errors
Correct answer: Chromatic aberration and lateral CA in the lens
Chromatic aberration—particularly lateral (transverse) CA—causes different wavelengths of light to focus at slightly different points, producing color fringing at edges.
Question 7: What is the primary advantage of a leaf shutter over a focal-plane shutter for flash sync?
- Leaf shutters allow any shutter speed to sync with flash, not just below a maximum sync speed (Correct answer)
- Leaf shutters are faster, achieving 1/8000s flash sync
- Leaf shutters eliminate motion blur entirely
- Leaf shutters increase flash output by reflecting light
Correct answer: Leaf shutters allow any shutter speed to sync with flash, not just below a maximum sync speed
Because the leaf shutter opens and closes within the lens, the entire sensor is exposed simultaneously at any speed, allowing full flash sync at all shutter speeds.
DIS Image Acquisition & Capture 3
In a RAW file workflow, which step converts linear light data captured by the sensor into a perceptually uniform image?