Influence of the ε parameter (fraction of magnetic energy used for the acceleration of non-thermal particles) on the spectral and structural properties of our M 87 simulations for a black hole with spin a_⋆ = 0.9375. The left column corresponds to a MAD model, and the right column shows a SANE model. Top panels: broad-band spectrum averaged for 2000 M for thermal and five different values of ε (colour-coded) while keeping R_low = 1, R_high = 160, and σ_cut = 1.0 fixed. The middle image shows the ray-traced 86 GHz images for different ε values. Bottom panels: jet diameter and opening angles profiles using the same colour-coding as for the spectrum.