Rolleiflex 3003 Brochure:

‘A mirror lens with supreme optical correction. No focal change needed for infrared photography. Twenty times the image size compared with standard focal lengths. Recommended for long-range photography, wildlife photography and reportage photography from very great distances using a tripod. Three individual grey filters can be swung in to reduce the incident light to aperture 5.6, 8 and 11.’  

 

5 elements in 5 groups
f5.6/8/11 grey filter
Angle of view: 2.5^o
Close focus distance:  12m
Filter size: Filter slide.