F110W,  (y − F110W) CMD for a metal-poor – M 92 (left) – and a metal-rich – 47 Tuc (right) – globular. The green and red solid lines display cluster isochrones. The adopted chemical compositions, age, true distance modulus and reddening are labeled. Tracks were computed by assuming α-enhanced chemical mixtures (PI06) and transformed into the observational plane by adopting atmosphere models with the same α-enhancement.