Proper-motion diagrams of stars in the field of view of NGC 1783 in five F438W magnitude intervals (left). The m_F438W vs. m_F438W − m_F814W CMD for stars in the left panels is plotted on the middle. Stars within the black circles plotted in the proper-motion diagrams are considered probable cluster members and are colored black, whereas field stars are represented with aqua crosses. The right panel shows the m_F438W vs. m_F275W − m_F438W CMD for probable cluster members, while the inset represents the Hess diagram of the CMD region around the upper MS.