Sigma today started offering a free-upgrade service to users of their EO-ETTL II flashguns. This range of Sigma flashguns does not work with the Canon EOS 50D SLR camera: the autozoom function does not work properly and the exposure is not correct.
These include Sigmaâ€™s EF-530 DG SUPER EO-ETTL II, EF-530 DG ST EO-ETTL II, EM-140 DG EO-ETTL II, EF-500 DG SUPER EO-ETTL II and EF-500 DG ST EO-ETTL II.
If you own any of these and you use the Canon EOS 50D, Sigma advises you to get in touch with their nearest service center for a free upgrade. Sigma assures that all new products shipped after today already include the updated firmware.