Anna This is partially my opinion and partially common sense. The specs limit the magnification for detecting defects because at higher magnifications defects may be called out which are not there. The 100X with a 200X referee has been both industry and military standard for many years now. However when it comes to measuring, you should not get a different value no matter what magnification you use. If with your microscope set up it is easier to measure at 200X then that is what I would do. For example when I measure internal annular rings on a qualification, I use 50X because the entire distance would not be in my field of vision at 100X and to move stuff around is a real pain. Susan Mansilla Technical Director Robisan Laboratory ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################