The same picture
Set up an A/B photograph comparison in which the result can be attributed to the variable you meant to test.
GUIDED LESSONStart here
Use this lesson before comparing cameras, lenses or edits. It helps you spot a changed viewpoint, exposure or processing setting that would otherwise make the result misleading.
By the end: Write a comparison question, choose one variable and record the conditions that must stay fixed.
What you need: One original raw file for an edit comparison, or a supported camera and stationary scene for a capture comparison.
Before you begin: A camera or phone and a stationary scene. Read Viewfinder before comparing focal lengths.
How to work through this lesson
- Write one question, such as “What does this white-balance change do?” Duplicate one raw file so capture conditions cannot change between versions.
- Change only the setting being tested. View both versions at equal size and display brightness, with other processing kept the same.
- Describe the visible difference and the limit of the test. For camera comparisons, also record position, lens, framing, exposure and processing.
Design a fair A/B comparison
An A/B comparison answers one question. First name the variable you intend to change, then list what must stay fixed. A different camera position, light level or edit can overwhelm the effect you wanted to inspect.
Compare at the intended output size as well as at high magnification. A difference visible only in a tiny crop may matter for a large print but not for a phone display. Neither view alone defines which picture is more useful.
Worked example
Original protocol: compare two white-balance settings on the same raw photograph. Duplicate the file, change only white balance and display both at equal size and brightness. Record which neutral area shifts and whether a warm subject remains plausibly warm. This isolates an edit parameter more cleanly than two photographs made hours apart.
Try it yourself
Write your answer before opening the explanation. Use the worked example if you get stuck.
Question 1
Two cameras photograph a building from different sidewalks using different lenses. One seems to have a larger background tower. Can this establish which sensor has better perspective rendering?
Show answer and reasoning
No. Perspective depends on viewpoint. Repeat from the same marked position and match the angle of view before discussing the rendering. Then compare the output under a stated size and processing policy.
Watch for: Automatic enhancement, sharpening, HDR and lens switching are experimental variables. Record or disable them when possible; do not conceal differences in the pipeline.
Summary + next step
Write a comparison question, choose one variable and record the conditions that must stay fixed.
Keep the result: Keep the paired files, original, exact settings and one sentence explaining the result.
Sources and further reading
Read these references for the concepts used in the lesson.
Lesson updated 2026-09-14 · Guidance updated 2026-10-22
Coverage and further development
Write a comparison question, choose one variable and record the conditions that must stay fixed.
Further development: Uploaded matched pairs and an interactive comparison slider.