Collection area at zenith angle of 10° for gamma rays at wobble offset of 0.4° for different stages of analysis: events triggered by both MAGIC telescopes (blue), events with at least two images surviving cleaning (orange), stereoscopic reconstruction with at least two images with intensity above 50 p.e. (green), cut in consistency of reconstructed arrival direction from different images (red), cut in angular distance between the true and reconstructed shower direction (violet). The bottom plot shows the ratio of the collection area at different stages to the MAGIC one at trigger level, with the band width reporting the statistical uncertainty.