- The classical method for determining target acquisition probabilities has always focused on the maximum spatial frequency (frmax) discernible in the image. On the other hand, it is known that the atmosphere degrades all the spatial frequencies as determined by the atmospheric modulation transfer function (MTF). The question arises: do the 'other' frequencies below frmax affect the target acquisition probability. We will present two experimental approaches to this question. In the first, we consider different atmospheric MTFs with the same value of frmax but with different MTF shapes. In the second, we consider a novel Wiener filter which restores all the frequencies to their value prior to the atmospheric blur. Laboratory measurements of observer response time when performing target acquisition will be presented for these case. The results will allow us to check the degree that the entire MTF should enter the target acquisition model, rather than frmax only.