Astrophotography Quiz: Darks, Flats, Stacking & Tracking

Master the technical demands of photographing the night sky. This quiz covers calibration frames (darks, flats, bias), stacking mathematics, tracking accuracy, and the precision techniques that produce stunning astrophotos.

Quiz 41: Astrophotography Precision: Sampling, Tracking, and Calibration Frames

"Dark frames" are used to:

Correct lens distortion

Subtract thermal noise/hot pixels pattern

Improve focus

Increase exposure

"Flat frames" are used to:

Correct vignetting and dust shadows

Reduce rolling shutter

Fix color casts

Increase sharpness

"Bias frames" are used to:

Measure readout bias pattern

Measure WB

Remove motion blur

Increase dynamic range

Dithering helps reduce:

Focus shift

Fixed pattern noise when stacking

Lens flare

Color gamut clipping

Tracking accuracy is limited by:

White balance

Polar alignment and mount quality

JPEG compression

Aperture blades

Seeing conditions affect:

Star size and detail due to atmospheric turbulence

ISO invariance

Lens distortion

Flash sync

Proper focus is often achieved using:

Auto focus on stars

Bahtinov mask or magnified live view on bright star

f/22 only

HDR merge

Aliasing in stars can occur when:

Oversampling massively

Undersampling (pixels too large relative to image scale)

Using RAW

Using flat frames

Stacking improves SNR by approximately:

N times

Square root of N

1/N

If you double the number of stacked frames, SNR improves by:

1.41x

0.5x

Light pollution primarily:

Improves contrast

Raises background level reducing contrast

Increases sharpness

Fixes WB

Narrowband filters are used to:

Increase ISO

Isolate emission lines and reduce light pollution impact

Improve autofocus

Reduce diffraction

Star trailing in tracked shots often indicates:

Perfect alignment

Poor polar alignment or guiding errors

Too low ISO

Too wide lens

Calibration frames must be:

Random

Shot at same settings/conditions (as applicable)

JPEG only

Different lens each time

Advanced astro workflow relies on:

One exposure only

Calibration, tracking, stacking, careful processing

Auto mode

HSS

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