Global performance comparison between multimode and singlemode interferometry, all sources of noise considered. Top: error of the phase in multimode (dotted lines) and singlemode (solid lines) as the function of the number of detected photoevents (per time unit) and K-band magnitude. For both cases, we can see the three regimes: the detector noise (in 1/N), then (shortly) the photon noise (in ) and finally the speckle noise (saturation). Bottom: ratio of multimode vs. singlemode phase error. Plots are shown for several levels of correction (Strehl ratios). The fixed parameters are σ_det = 4e ⁻ / pix,  |Vij |  = 1, N_pix = 4. Two turbulence strengths are considered D/r₀ = 8 (left) and D/r₀ = 2 (right) that correspond to the average turbulence conditions of the VLTI with UTs (D = 8 m) and ATs (D = 1.8 m) respectively. For the conversion between detected photoevents and magnitude scale, we have considered a total transmission coefficient of 15%, a detector quantum efficiency of 50%, an integration time of 30 ms and a spectral resolution of 35 with 2 pixels by spectral channel.