---
title: 2.7 Tips for a Good Capture
description: "Regardless of capture mode, the following practices produce the best analysis results: ****Lighting**** - Use diffuse, even illumination — the built-in iriscope LED ring is ideal. - Avoid harsh shadows across the iris. - Avoid reflections from overhead lights on…"
url: "https://cnri.edu/docs/2-7-tips-for-a-good-capture/"
updated: "2026-03-24"
category: Capturing Eye Images
---

# 2.7 Tips for a Good Capture

Regardless of capture mode, the following practices produce the best analysis results:

****Lighting****

- Use diffuse, even illumination — the built-in iriscope LED ring is ideal.

- Avoid harsh shadows across the iris.

- Avoid reflections from overhead lights on the cornea; slight repositioning eliminates most reflections.

****Distance & framing****

- The iris should fill at least 50% of the frame width.

- Keep the iris centred; a pupil near the edge of the frame reduces decentration accuracy.

- For the Dino-Lite, the optimal focal distance is approximately 2–3 cm from the eye.

****Stability****

- Rest the device or brace your hand to eliminate motion blur.

- Ask the patient to fixate on a distant point to minimise involuntary eye movement.

- Capture during natural blinking pauses — the image quality gate automatically rejects frames taken during a blink.

****Grade guide****

After analysis, each eye receives a quality grade:

| Grade | Meaning |

|-------|---------|

| ****A**** | High confidence — all metrics within optimal range |

| ****B**** | Good confidence — minor limitations, results reliable |

| ****C**** | Reduced confidence — consider recapture if possible |

| ****D**** | Low confidence — recapture recommended before clinical use |