[en] In order to have a good statistics, fast neutron capture measurements are usually performed with a pretty big sample. However, corrections for finite geometry, for neutron and γ-ray absorption and for neutron multiple scattering can be very important and, consequently, have to be calculated accurately. Depending on the size of the sample, simple and fast analytical expressions or more accurate but time consuming Monte-Carlo techniques must be used. We show that for angular distribution measurements, especially for small asymmetry factors, the Day approximation cannot be used the but Monte-Carlo technique instead. These techniques are applied to the ¹⁹⁷Au(n,γ) total and ²⁰⁸Pb(n,γ₀) partial cross section measurements