For known gravitational lens systems the redshift distribution of the lenses is compared with theoretical expectations for about ten thousand Friedmann-Lemaître cosmological models, which more than cover the range of possible cases. The comparison is used for assigning a relative probability to each of the models. The entire procedure is repeated for different values of the inhomogeneity parameter eta as well as H_0 and the limiting spectroscopic magnitude, which are important for selection effects. The dependence on these three parameters is examined in more detail for lambda=0 and k=0.
The previous result of other authors that this method is a good probe for lambda_0 is confirmed, but it appears that the low probability of models with large lambda_0 values reported by these authors may be due to a selection effect. The power of this method to discriminate between cosmological models can be improved dramatically if more gravitational lens systems are found.