Coupled rangefinder/parallax 4×5 camera

#The invention relates to an interface for changing the film format of cameras and the modification of a 3¼″×4¼″ format camera into a 4″×5″ format camera utilizing such interface. In particular, the interface is a modification of a Polaroid CB 103 film magazine, which is designed for 3¼″×4¼″ film format, to accept films in the 4″×5″ film format.

#Different film formats exist for still photography to accommodate the needs and demands in the art of still photography. The most common small film format is the 35 mm used in common point and shoot camera. The medium film format is between 35 mm and 6 cm in height, which includes 6 cm×9 cm and 3¼″×4¼″, which is commonly referred to as 3¼×4¼. The large film format is greater than 6 cm in height, which includes 4″×5″, commonly referred to as 4×5, and 8″×10″, commonly referred to as 8×10.

#Larger film sizes provide better quality and more detail images. The largest practical format for a production hand held camera is the 4×5 format because of the limitation on the portability and maneuverability of the camera. An 8×10 format camera is heavy and cannot be used as a hand held camera.

#FIGS. 1A-1D show different views of a Polaroid Model CB 103 film magazine, in the open and closed position, FIG. 1E shows the closing latch of the Model CB 103 film magazine; and FIGS. 1F and 1G shows different views of the pack film holder of the Model CB 103 film magazine.

#FIG. 2 is a CB 103 interface modified from a CB 103 film magazine in accordance with the present invention.

#FIGS. 3A-3F show the steps of modifying a CB 103 film magazine into a CB 103 interface and then into a 4×5 adaptor in accordance with the present invention.

#CB 103 Interface

#With reference to the drawing wherein the same reference number illustrates the same element throughout, FIGS. 1A-1D show a Polaroid CB 103 film magazine 1 for the 3¼×4¼ format pack film, which is to be modified to become a CB 103 interface 10. FIGS. 1A and 1B show the front and rear, respectively, of the CB 103 film magazine 1 in the closed position and FIGS. 1C and 1D show the front and rear, respectively, of the CB 103 film magazine 1 in the open position. The CB 103 film magazine 1 has a frame 2, which is pivotally connected to a rear door 4 on one end and to a closing latch 6 on the opposite end. FIG. 1E shows the closing latch 6 separated from the frame 2. As shown in FIGS. 1A and 1B, the rear door 4 rests on the frame 2 with the closing latch 6 latching over the rear door to keep the CB 103 film magazine 1 in the closed position. Mounted on the frame 2 at the pivoting point between the frame 2 and rear door 4 is a pack film holder 8. As shown in FIGS. 1F and 1G, pack film holder 8 has a pressure spring 12 for retaining a pack film (not shown), which is inserted into the pack film holder 8 when the CB 103 film magazine 1 is in the open position as shown in FIG. 1C. Upon closing the CB 103 film magazine 1, the pack film (not shown) rest against another pressure spring 14 mounted on the rear door 4. Also mounted on the rear door 4 adjacent the end opposite from the frame 2 is a pair of film development rollers 16. When in use, after photographing an image on a pack film, a photograph exits the CB 103 film magazine 1 through the film development rollers 16 and an exiting slot (not shown) on the side of the rear door 4.

#The modification of the CB 103 film magazine 1 shown in FIGS. 1A-1D, to a CB 103 interface 10, as shown in FIG. 2, requires the removal of the film development rollers 16 and milling an opening 18 in the rear door 4. The CB 103 interface 10 interfaces a camera that accepts a CB 103 film magazine 1 and another camera back having a different film format, such as a film holder a film holder receiving apparatus or a 4×5 frame. Additionally, the CB 103 interface 10 acts as a spacer to advantageously increase the distance between the lens and the film plane. The milled opening 18 is preferably centered on the rear door 4 such that when CB 103 interface 10 is mounted onto a camera (not shown), the projected image will properly travel through the milled opening 18 onto the film while maintaining and respecting the functions of the parallax system of the camera with the increased distance between the lens and the film plane. Depending on the focal distance of the lens and the size of the film being used on the camera, the thickness or depth of the CB 103 interface 10 may be increased from the distance between the lens and the film plane for proper function of the parallax system on the camera and the proper image size for the specific format film. CB 103 interface 10 as shown in FIG. 2 has a milled opening 18 of approximately 4″×5″ for adapting to a 4×5 format. Different sized opening 18 may be milled for different purposes, e.g. 35 mm, 6 cm×9 cm, 5×7, etc.