Hi Harang, Did you open multiple models? If you did, then it sounds like those models are so far away from each others that when camera zooms so much back that all fits in view, nothing is visible. Select a model from the Models panel and then hit space in keyboard. That should zoom to the selection. Some times selecting the model does not work as the model as some objects far away from each other, in this case open Objects tab and select on object and hit space again to zoom to that. Does that help? Best regards, Marko Myllymaa