The ISO 12233 standard for digital camera resolution includes two methods for the evaluation of camera performance in terms of a Spatial Frequency Response (SFR). In many cases, the measured SFR can be taken as a measurement of the camera-system Modulation Transfer Function (MTF), used in optical design. In this paper, we investigate how the ISO 12233 method for slantededge analysis can be applied to such an optical design. Recent improvements to the ISO method aid in the computing of both sagittal and tangential MTF, as commonly specified for optical systems. From computed optical simulations of actual designs, we apply the slanted-edge analysis over the image field. The simulations include the influence of optical aberrations, and these can present challenges to the ISO methods. We find, however, that when the slanted-edge methods are applied with care, consistent results can be obtained.