Correction to the Field of View for the High Altitude Observatory Mark-Iii K Coronameter

The field of view widely in use for representation of the coronal data collected with the Mark III K-coronameter at Mauna Loa is incorrect. Analysis of the observations of a partial solar eclipse in August 1980 and of observations of high eruptive prominences seen both with the K-coronameter and the occulted Hα chromospheric telescope at Mauna Loa indicate that the field of view actually begins 0.09 R_☉ higher than thought; the pixel-to-pixel separation is as originally published. We describe the analysis which leads to the description of the image scale and discuss both the qualitative and quantitative effects of this new information on published results.