We have carried out photometry of stellar images from plates taken with a Kron electrographic camera and measured with a PDS 1010 microdensitometer. Attention has been given to significant sources of error in measurement and reduction of the stellar images and in photometric calibrations of the electrographic camera. These include: sky background noise crowding plate defects detector areal response color transformations linearity mjcrodensitometer errors. Each has been investigated in isolation in order to minimize its contribution to the photometric uncertainty of a stellar measure. As in conventional photoelectric photometry some sources of error are difficult to reduce below the one percent level. For well exposed stellar images the photometric uncertainty deduced from comparisons with photoelectric calibrations is less than 3 percent for a single measure. Although the techniques described were developed using electrographic camera plates measured on a PDS microdensitometer, the general principles are applicable to photometry with any type of panoramic detector.