ROLL-FILM CAMERA INTO A DIGITAL CAMERA

Since digital cameras became the dominant platform in the photography marketplace, several attempts have been made to introduce a commercial solution to convert existing film cameras into digital cameras. In these attempts, the electronic circuits required for the conversion were successfully miniaturized to fit into the film chamber of standard cameras. However the overall solutions failed in performance because of the difficulty in synchronizing the original mechanical shutter with the new digital circuitry. Noise made by the mechanical shutter when opening and closing, and light falling on the image sensor when the shutter is open were the two methods used to trigger digital capturing of the image. Such solutions are complicated to implement and rely on the precision of the original mechanical shutter in the camera, which is not always reliable.

According to a first aspect of the invention, there is provided a method for converting a film camera into a digital camera as defined in claim 1.

According to a second aspect of the invention, there is provided a converted film camera as defined in claim 13.

The inventor has developed a new solution for film to digital conversion by disabling the original mechanical shutter at a fixed open position and introducing a live digital optical sensor with a new electronic shutter which allows recording of images. The digital solution of the invention can be used in viewfinder, rangefinder, single lens reflex (SLR) and twin lens reflex (TLR) film cameras that operate in manual mode.

The invention addresses two problems related to mechanical shutters and conversion of film cameras into digital. First, the need for synchronizing the mechanical shutter with the electronic image capture is negated (which also allows recording of video). And second, the common problem of mechanical shutter malfunction in vintage film cameras is bypassed. Embodiments of the present invention will now be described by way of further example only and with reference to the accompanying drawings, in which:

Fig. 1 shows a horizontal cross-section of a converted camera according to an embodiment of the invention; and

Fig. 2 shows a rear view of a converted camera according to an embodiment of the invention.

As shown in Figs. 1 and 2, a film camera converted into a digital camera 100 using a method according to the invention features a lens 2 and a camera body 4. On the back 16 of the camera body 4 is mounted a shutter base 6. The shutter base 6 has an electronic shutter button 8 and a micro-USB port 10. Within a film chamber inside the camera body 4, an electronic image sensor 12 is provided. The image sensor is located in a film mounting area where the film would be in the original film camera, so that the image of an external subject formed by the lens 2 is formed at the image sensor 12.

The image sensor 12 is connected to digital circuitry 14 including a CPU and memory, and preferably also a wireless communication device. The digital circuitry 14 operates to drive the image sensor and store the images captured by the image sensor in the memory. The digital circuitry 14 is located in the film chamber where the cylindrical film container would normally fit in the original film camera.

The digital circuitry 14 is also connected to the electronic shutter base 6. By operating the electronic shutter button 8, a user can control the digital circuitry 14 to operate an electronic shutter for the image sensor 12. Furthermore, the battery of the digital circuitry 14 can be charged via a charging cable attached to the micro-USB port 10 of the shutter base 6. The micro-USB port 10 can also be used to download images from the memory to an external storage device. The camera has an original mechanical shutter button 22, which is disabled in the converted camera 100. The camera also has an optical viewfinder 18, which is still usable in converted manual viewfinder and rangefinder cameras. However, the optical viewfinder 18 is not usable in converted SLRs since the mirror of the SLR is fixed so as to direct light onto the image sensor 12 rather than to the optical viewfinder 18.

An electronic viewfinder 20 is optionally also provided on the converted camera. The electronic viewfinder 20 is connected to the micro-USB port 10. The live image captured by the image sensor 12 is relayed to the electronic viewfinder 20 via the digital circuitry 14 and the electronic shutter base 6, and is displayed on a screen of the electronic viewfinder 20.

In the conversion method of this embodiment, the digital circuitry 14 (CPU, memory and wireless boards) and the battery are placed into a cylindrical enclosure that fits into the original film chamber. The image sensor 12 is precision fixed into its film replacement position using the film rails and is connected to the digital circuitry 14 by a cable. The film pressure plate is removed to provide room for the sensor 12 when the camera back cover 16 is closed.

The original mechanical shutter is disabled and fixed at an open position (in case of an SLR, the mirror is fixed at the position where the image is directed on to the sensor and not to the eyepiece). In this setting, the digital image sensor 12 can "see" a constant live image through the lens. The aperture is set manually using the original dials on the camera or lens 2. Once the aperture is set, light metering and exposure are controlled automatically by the live image sensor 12 and the new digital circuitry 14. This is in effect like shooting in "aperture priority" mode with an automatic digital camera. Because the mechanical shutter is disabled, noise related to the mechanical opening and closure of the shutter apparatus is also avoided improving the image quality.

To operate the electronic shutter, a hole is drilled in the back cover of the camera 100 under the right thumb of a user in the normal grip position and a new shutter button 8 and its base 6 are placed across this hole. The new shutter button base 6 is also connected with a cable internally to the digital circuitry 14. On the outside surface, in addition to the electronic shutter release 8, the base houses a micro USB port 10 and a second switch (not shown) to override and increase or decrease the automatically set exposure. The electronic shutter release button 8 also operates as on/off switch when pushed and held. Multifunctional micro USB port 10 is used for recharging the internal battery, uploading software, downloading image and video files onto another computer, connecting to an external monitor for viewing images or video in memory, and connecting to an electronic viewfinder accessory.

In a converted camera according to the invention, focusing is done by the original systems and dials of the film camera 100. In manual viewfinder cameras, framing is done by the optical viewfinder 18 and the correct focus is set by guessing the distance to the subject as in the original camera. In manual rangefinder cameras, framing and focusing is done by the range finding apparatus within the optical viewfinder 18. Since the conversion renders the original viewfinder of SLRs nonfunctional, a new electronic viewfinder accessory 20 needs to be attached to the converted SLRs. Framing and manual focusing is then done through this add-on electronic viewfinder 20. The electronic viewfinder 20 is connected to the internal electronics 14 and image sensor 12 by a micro USB cable through the base 6 of the new electronic shutter. The electronic viewfinder accessory 20 is also very useful in viewfinder and rangefinder cameras to improve precision of manual focusing and where the rangefinder apparatus is faulty.

Recorded images and video are stored on a memory card within the internal digital circuitry 14 and by wirelessly transferring and recording on to a smartphone, tablet or other computer where a wireless communication device is provided in the digital circuitry 14. Those images and video can be reviewed on the screen of the smartphone or via the electronic viewfinder accessory 20. A dedicated software application on the smartphone or tablet computer manages the image and video files and is also used to adjust certain parameters of the digital circuitry 14 within the camera 100 such as sensitivity (film speed) and other digital calibrations that are needed. The foregoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention.