New review tool: X-Rite i1Pro Spectrophotometer

Introduction

I've wanted a spectrophotometer for quite some time. A spectro-what, you say? A photometer or luxmeter measures the brightness of all the visible light hitting it. A spectrophotometer measures the brightness of each of many small slices of the spectrum hitting it, allowing precise characterization of the light. Its major application in the flashlight world is measuring color temperature, tint, and color rendering index.

Pictures of the instrument itself aren't very interesting; you're probably here for the flashlight measurements.

Glossary

• CCT - a representation of how blue or yellow/orange a light source looks. Higher is more blue; an incandescent light bulb is about 2700K and midday sunlight is about 5000K. The abbreviation means Correlated Color Temperature and represents how hot an object would have to be to glow the same shade of white.
• Duv - a measure of red/green balance. Positive is green, and negative is red. Zero is pure white. These numbers are very small, with anything over 0.006 in either direction falling outside the ANSI standard for white light.
• Ra - This is the most commonly used and quated measure of color quality in lighting. Often simply referred to as CRI, this is the average color rendering index over eight color samples.
• R9 - an extension to CRI not included in the standard average representing accuracy of a deep red sample. LEDs tend to perform poorly here.
• R12 - another extension to CRI with a deep blue sample. LEDs also tend to perform poorly here.

I have marked unusually bad and unusually good numbers.

Measurements

All measurements were taken on a reasonable medium mode in the center of the beam, diffused with DC Fix diffusion film.