One of these can be pinhole or single-lens reflex
Both of these cameras used M42 screw thread lenses 
as did the Pentax... [DOC] [TLE] Digital single-lens reflex camera - Wikipedia [PAR] A digital single-lens reflex camera is a digital camera that combines the optics 
and the ... By using only one lens, the viewfinder of a DSLR presents an image 
that will ...