The spectral lines of resolution will be equal to half the number of images collected in the recording. If the "Duration Type" is set to "Number of Frames" it will be based on the  number you entered. If the "Duration Type" is set to "Time(sec)", it will be as shown in the lower left corner under the "Calculated Values" heading.

The Number of Frames entry under the "Recording Properties" when recording in Frames:


The Number of Frames as found under the "Calculated Values" heading when acquiring for a specified time: