This is a large survey carried out using the Canada-France-Hawaii Telescope, completed in 2008. The total area is about 140 square degrees, which have been imaged in ugriz, allowing for photometric redshifts for the sources to be derieved. The survey will provide the best constraints on a number of cosmological parameters, including the dark energy equation of state, from weak lensing. It also serves as a pathfinder for much larger projects.

The analysis of the data requires a large team of astronomers, most of them shown in the picture below. The CFHT Lensing Survey (CFHTLenS) team has been busy developing and testing all the tools needed to extract the tiny cosmic shear signal from this great data set. More information can be found at the team website.