Whether performing routine tensile testing, measuring Poisson’s ratio, or conducting full-field strain analysis, correct sample marking is essential for reliable, repeatable strain data. This article provides a comprehensive guide to sample marking for video extensometers, explains how digital image correlation (DIC) works, and outlines best practices for achieving high-quality strain measurements across a wide range of materials.

If you’re trying to choose between a video (non-contact) extensometer and a clip-on (contact) extensometer, the best answer depends on what you test, how often you change specimen types, your accuracy needs, your risk tolerance for damaging samples, and—very often—budget.

Learn when to use an extensometer and why it is important for tensile testing on a universal testing machine.