For the long-focal length lens,a method that can test the lens′ wavefront and focal length at the same time is presented by using a concave spherical mirror.The test error of this method is analyzed.Then,the influence of measuring error and alignment error on the test result is analyzed in detail,and the relative sensitive degrees of freedom needed to be controlled in the test process are determined.The result shows that,the lens with F/#≥50 can be tested with this method with a relative error f...