У адобы есть такой коммент по 50D: "Using the 50D in Windows, images can fail to come into the computer if the compact flash card is inserted or removed during the session."Настройки для работы:http://help.adobe.com/en_US/lightroom/using/WS67a9e0c3a11b14966badab91285ff688ee-8000.htmlНу и решение проблем с tethered mode:http://helpx.adobe.com/lightroom/kb/troubleshoot-tethered-capture-lightroom-4.html