End of the ninetees, I had a chance to take pictures with this prototype "dream lens" APO Teletessar T* 4/600mm + 1,5x doubler = 5,6/840mm! At the "analogue time", I was shooting with an Fuji Sensia 100 slide film. The results were absolutely incredible!!! Only three prototype lenses of this APO 4/600mm have been build.