As the industry standard for interferometer frequency response specifications, ITF has historically been calculated using expensive phase targets to capture interference-based phase information. Recent work in transfer function characterization of interferometers has produced a more accessible technique with the ability to predict a system's ITF utilizing a modified amplitude edge response. This technique does not require a phase measurement and demonstrates correlation between the ITF and an amplitude edge response for coherent systems, even in the presence of significant defocus. Defocused instruments exhibit modulation dropout in their transfer functions, now shown to be related to the Talbot Effect, exhibited here by imaging both phase and amplitude single frequency, square wave targets. This presentation outlines the modified amplitude edge response technique, utilization, and results for focused and defocused system characterization.