Isochrone fitting results of NGC 6611. Top-left: best-fit isochrone with A_V = 2.0 ± 0.1 mag and age of 7.5 ± 0.4 Myr shown with the solid cyan line to the early type stars and the blue group (with and without spectral type). An open symbol represents a known spectral type, while a closed symbol does not. The uncertainty on the age for A_V = 2.0 mag is shown with the cyan shaded region. The stars with known spectral type are corrected for extinction according to the best-fit A_V with R_V = 3.56 (Kumar et al. 2004). Bottom-left: log-likelihood for each isochrone in the searched A_V-age grid for the stars indicated in the top-left figure. Each point in the grid is coloured according to its (unnormalised) likelihood value. The log-likelihood gives the quality of the fit, with smaller negative values (in lighter grey) representing better fits. The cyan cross and circle indicate the best-fit A_V and age with 1σ uncertainty range. Top-right: similar to the top-left figure, but now for the early type stars and the red group (with and without spectral type). The solid cyan line gives the best-fit isochrone with A_V = 3.5 ± 0.1 mag and age of 1.3 ± 0.2 Myr. The uncertainty on the age for A_V = 3.5 mag is shown with the cyan shaded region. Bottom-right: similar to the bottom-left figure, but now for the top-right figure.