Multiple images of quasars formed by gravitational lensing are typically seen through the lensing galaxy. The granulation of the galaxy in stars or other compact objects induces local (`microscopic') but strong fluctuations in the gravitational potential that subdivide each image in several micro-images changing the expected flux of the image (flux

We present the results of a long M87 monitoring campaign in very high energy $gamma$-rays with the MAGIC-I Cherenkov telescope. A total of 150 hours of data was gathered between 2005 and 2007. No flaring activity was found during that time. Nevertheless, we have found an apparently steady and weak signal at the level of $7sigma$. We present the

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