In one exemplary embodiment, a method for calibrating an instrument is provided. The instrument includes an optical system capable of imaging florescence emission from a plurality of reaction sites. The method includes performing a region-of-interest (ROI) calibration to determine reaction site positions in an image. The method further includes performing a pure dye calibration to determine the contribution of a fluorescent dye used in each reaction site by comparing a raw spectrum of the fluorescent dye to a pure spectrum calibration data of the fluorescent dye. The method further includes performing an instrument normalization calibration to determine a filter normalization factor. The method includes performing an RNase P validation to validate the instrument is capable of distinguishing between two different quantities of sample.