Photography Exposure and Metering 4 — Questions and Answers
Question 1: What is 'long exposure noise reduction' (LENR) and when is it most useful?
- It sharpens images blurred by camera shake during long exposures
- It captures a dark frame of equal duration after the exposure to subtract thermal noise patterns (Correct answer)
- It automatically increases ISO during nighttime photography
- It reduces file size on exposures longer than 1 second
Correct answer: It captures a dark frame of equal duration after the exposure to subtract thermal noise patterns
LENR takes a dark frame (same duration, shutter closed) immediately after the main exposure and subtracts its thermal noise pattern from the image.
Question 2: A photographer notices the histogram of their image has a large gap on the right side. What does this indicate?
- The image is overexposed with blown highlights
- The image is underexposed and could be brightened to use more of the dynamic range (Correct answer)
- The image has correct exposure with good highlight detail
- The image has too much contrast
Correct answer: The image is underexposed and could be brightened to use more of the dynamic range
A histogram with empty space on the right side means the image is underexposed — there are no bright tonal values being recorded and exposure could be increased.
Question 3: What is the reciprocity failure phenomenon, and for which type of photography is it most relevant?
- A lens aberration where focus shifts at different apertures; relevant to macro photography
- The breakdown of the linear relationship between exposure time and film density at very long exposures; most relevant to long-exposure film photography (Correct answer)
- When two cameras with different sensors produce different exposures; relevant to studio work
- A shutter speed error that appears only above 1/8000s; relevant to sports photography
Correct answer: The breakdown of the linear relationship between exposure time and film density at very long exposures; most relevant to long-exposure film photography
Reciprocity failure occurs in film when very long exposures (seconds to minutes) require additional exposure beyond what calculations predict because the film's response becomes nonlinear.
Question 4: A photographer sets shutter speed to 1/250s and aperture to f/8 at ISO 400. To maintain the same exposure while switching to f/4, which adjustment is needed?
- Change shutter speed to 1/1000s (Correct answer)
- Change shutter speed to 1/60s
- Raise ISO to 1600
- Raise ISO to 3200
Correct answer: Change shutter speed to 1/1000s
Going from f/8 to f/4 gains two stops of light, so the shutter speed must be increased by two stops (1/250s → 1/500s → 1/1000s) to compensate.
Question 5: What is 'exposure bracketing' and why do photographers use it?
- Shooting with multiple lenses simultaneously to cover different focal lengths
- Capturing a series of shots at different exposures to ensure at least one is correct or to merge into HDR (Correct answer)
- Using a bracket to stabilize the camera during long exposures
- Setting exposure using manual calculations rather than the meter
Correct answer: Capturing a series of shots at different exposures to ensure at least one is correct or to merge into HDR
Exposure bracketing shoots the same scene at several exposure values (e.g., -2, 0, +2 EV) to ensure an ideal exposure or to provide frames for HDR merging.
Question 6: What effect does shooting through a UV-absorbing haze filter have on exposure?
- It requires about 2 stops more exposure to compensate
- It has negligible effect on exposure because it is nearly optically clear in visible light (Correct answer)
- It reduces exposure by 1 full stop in bright sunlight
- It doubles the effective ISO required
Correct answer: It has negligible effect on exposure because it is nearly optically clear in visible light
UV filters transmit virtually all visible light, so they have no meaningful impact on metered exposure — unlike ND or polarizing filters.
Question 7: In what situation would a photographer MOST benefit from using exposure lock (AE-L)?
- When shooting a stationary portrait where the subject fills most of the frame
- When recomposing after metering a specific area that won't be centered in the final image (Correct answer)
- When using manual mode to eliminate all automatic adjustments
- When shooting video to maintain continuous autofocus
Correct answer: When recomposing after metering a specific area that won't be centered in the final image
AE-L locks the metered exposure value so the photographer can meter a specific subject or tone and then reframe without the camera recalculating exposure.
Photography Exposure and Metering 4
What is 'long exposure noise reduction' (LENR) and when is it most useful?