We have observed two blank fields of approximately 30 by 23 arcminutes using the William Herschel Telescope .
The fields have been studied as part of the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey ( CNOC2 ) , and spectroscopic redshifts are available for 1125 galaxies in the two fields .
We measured the lensing signal caused by large scale structure , and found that the result is consistent with current , more accurate measurements .

We study the galaxy-galaxy lensing signal of three overlapping samples of lenses ( one with and two without redshift information ) , and detect a significant signal in all cases .
The estimates for the velocity dispersion of an { L } ^ { * } _ { B } ( z = 0 ) = 5.6 \times 10 ^ { 9 } ~ { } h ^ { -2 } { L } _ { B \odot } ~ { } galaxy agree well for the various samples .
The best fit singular isothermal sphere model to the ensemble averaged tangential distortion around the galaxies with redshifts yields a velocity dispersion of \sigma _ { * } = 130 ^ { +15 } _ { -17 } km/s , or a circular velocity of V _ { c } ^ { * } = 184 ^ { +22 } _ { -25 } km/s for an { L } ^ { * } _ { B } galaxy , in good agreement with other studies .

We use a maximum likelihood analysis , where a parameterized mass model is compared to the data , to study the extent of galaxy dark matter halos .
Making use of all available data , we find \sigma _ { * } = 111 \pm 12 km/s ( 68.3 % confidence , marginalised over the truncation parameter s ) for a truncated isothermal sphere model in which all galaxies have the same mass-to-light ratio .
The value of the truncation parameter s is not constrained that well , and we find s _ { * } = 260 ^ { +124 } _ { -73 } ~ { } h ^ { -1 } kpc ( 68.3 % confidence , marginalised over \sigma _ { * } ) , with a 99.7 % confidence lower limit of 80 ~ { } h ^ { -1 } kpc .
Interestingly , our results provide a 95 % confidence upper limit of 556 ~ { } h ^ { -1 } kpc .
The galaxy-galaxy lensing analysis allows us to estimate the average mass-to-light ratio of the field , which can be used to estimate \Omega _ { m } .
The current result , however , depends strongly on the assumed scaling relation for s .

Subject headings : cosmology : observations - dark matter - gravitational lensing