To provide a film unit with a lens adequate for photographing in a room and at night, and a method for preparing a printed picture.

As to this film unit with the lens; a stop value A by a diaphragm plate 41, the shutter speed T of a shutter device, and the ISO sensitivity S of a photographic film 26b are decided so as to satisfy the condition of the expressions of -6≤2 log2 (A)+log2 (1/T)-log2 (0.3.S)≤5. The guide number of a stroboscopic device 23 is decided to be 0.1 to 8. When the photographing is performed in such a dark place as the inside of the room, the printed picture in which a main object and a back ground are adequately described can be prepared. A straight line part is extended to the foot part of the characteristic curve of the film 26b and tone correction is performed by digital image processing, so that the printed picture having good tone reproduction can be prepared from an underexposed photographic film.