Abstract: In a color television receiver having an in-line electron beam kinescope and deflection yoke, a correction apparatus comprises a pair of magnetically permeable field formers located on opposite sides of the yoke. A first portion of each field former lies within the external field of the vertical deflection coils and channels flux from the external field into the field formers. A second portion of each field former is configured to form a pair of feet located above and below the longitudinal axis of the kinescope. Flux channelled into the field formers is directed by the feed to form a pincushion-shaped field within the kinescope neck to correct vertical coma errors. A third portion of each field former lies forward of the feet and directs the channelled flux to form a barrel-shaped field within the kinescope neck to correct any misconvergence of the outer electron beams caused by the coma correcting field.