SINGLE LENS REFLEX CAMERA PROTECTOR

FIELD OF THE INVENTION

This invention relates to the protection of the sensor or film from dust and other foreign objects in single-lens reflex cameras.

BACKGROUND TO THE INVENTION

All cameras which utilises a facility to change lenses suffer from the possibility that dust or foreign objects may enter the camera body and end up on the sensor or film.

The objects enter the body while the lens is exchanged and the body is open and also when the zoom functions of the lens is utilised. The zoom lens operates as a type of a pump, when the lens is moved from the two extreme positions, air is sucked in and displaced and this could contain dust that could end up in the camera body.

In digital cameras the accumulation of the dust and foreign particles produce negative effects in the higher f-stop ranges and could show up as blobs and the like in photos. This problem is less pronounced in film cameras as the accumulation effect is smaller and the body could be cleaned without the receptive material (film) in the camera.

The problem of accumulated dust and foreign particles in a digital SLR camera is overcome by cleaning the sensor. Many products are available on the market and they all use basically the following:

1 . De-dusting: Utilising a blower of some kind to remove the loose particles; and

2. Cleaning the Sensor: Utilising a solvent of some kind, which do not leave any marks after drying, to clean the sensor with a swab that would not leave any particles behind.

Apart from the above, camera manufacturers utilise all sorts of mechanisms to reduce the effect. Some of these include coating the sensor with antistatic coatings, and installing vibrating mechanisms to vibrate and thus shake off the dust from the sensor.

A further problem with cameras with removable lenses is differing lens mounts used by different manufacturers. Incompatible lens mounts means cameras from certain

manufacturers may only be fitted with lenses from the same manufacturer or specialised third party lenses.

OBJECT OF THE INVENTION

It is an object of the invention to provide a protector for a single-lens reflex camera to at least partly overcome the above problems.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a protector for a single reflex camera, the protector comprising a body having at one side attachment means complementarily configured to the lens mount on the camera and on the opposite side a lens mount complementarily configured to a predetermined lens type, and located within the body a shield configured to isolate the interior of the camera from its surroundings and allow light to travel through the protector, and preferably for the shield to comprise a lens configuration to correct the focus point of light received in the camera for the increased path length of light traveling though the protector.

There is further provided for the lens mount on the camera side of the protector and lens mount on the lens side of the protector to preferably be configured for devices for the same camera manufacturer, alternatively for lens mounts of devices for different manufacturers.

There is further provided for the protector to include communication means configured to relay electrical or electronic signals between the camera and the lens.

A still further feature of the invention provides for the protector to include filters, erg. a UV, polarizer, neutral density or any other suitable filter for an occasion.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic cross section of a typical SLR camera, showing the lens, camera body inside and the view finder parts of the camera. It also indicates ray trace information;

Figure 2 is a diagrammatic cross section of a typical SLR camera, showing the lens, camera body inside and the view finder parts of the camera as well as a protector, showing the focus point movement after installation of the protector with only a flat optical element being the dust barrier, with no correction;

Figure 3 is a cross section of a protector, showing optical element/s which corrects the focus point shift and creating the dust barrier; and

Figure 4 is a cross section of a protector, showing optical element/s, as in figure 3, with the addition of a replaceable filter, which would protect the optical elements and which could be used for photographic purposes.

Figure 5 is a diagrammatic cross section of a typical SLR camera, showing the lens, camera body inside and the view finder parts of the camera. It also indicates ray trace information and a dust barrier designed inside the camera body.

DETAILED DESCRIPTION OF THE INVENTION

Any Single-Lens Reflex (SLR) camera is prone to dust getting inside the camera body. Figure 1 shows a diagrammatic cross section of a typical SLR camera (1 ). Three distinct areas are highlighted in Figure 1 : the view finder part (2) is at the top of the camera (1 ), the lens area (3) is to the left and the optical area (4) is inside the body (5) of the camera (1 ).

Light (6) travels through the lens (3) onto the mirror (7) and is reflected through the penta prism (8) to the view finder eye piece (9). The camera operator uses this view to change settings on the camera (1 ) and also make the composition of the picture. When the camera operator takes the picture the mirror (7) swivels upwards which allows the light (6) to impact directly onto the optical sensor (10), which could be film or a digital sensor.

The big advantage of SLR cameras (1 ) is their ability to utilise a vast range of different lenses to capture the light (6) on the sensors in the optimum way.

With this advantage comes the disadvantage of opening the camera (1 ) to the ingress of dust and foreign particles, which reduces the efficiency of the optical receiver (10) (film or sensor).

In dusty or moist conditions the removal of a lens may result in small particles being blown into the camera body (5). To remove the foreign particles is costly if done by a professional

and risky with the potential of costly damage if done by a less than properly skilled camera operator.

This invention provides for the installation of a protector (1 1 ) which acts as a barrier between the lens (3) and the inside of the camera (1 ).

Figure 2 shows a cross sectional view similar to that of Figure 1 with the protector (1 1 ) in position on the camera (1 ). The protector (1 1 ) is not removed during lens changes and keeps the inside of the camera (1 ) protected. If a pure filter element (12) is included as shown, the focus points (13) would be moved and the camera (1 ) would loose the ability to focus at infinity.

A cross sectional view of the camera and protector of Figure 2 is shown in Figure 3. Optical elements are shown in Figure 3 to compensate for the shift in the focus point (13) due to the thickness of the dust protector, which increases the path length light travels to the optical sensor (10). This will prevent loss of focus when focusing on objects at infinity.

The design of the optical elements (14) is dependent on the change in focal length and would be designed to meet the requirements of each camera/lens mount type. In the most basic form the protector (1 1 ) would only have corrective optical elements.

Figure 4 shows an embodiment of a protector (20) which includes a removable filter (21 ). This would protect the optical elements against damage and would also benefit the photography.

Figure 5 shows an embodiment of a protector (22) which is part of the camera design and incorporated within the camera body (5). In future, camera designs could include this optical protective barrier in the camera. If enough space exists in the camera, there would be no change in focus point (13). If additional space needs to be created for such a barrier, a lens arrangement would be required to correct for the change in focus points (13).

In this embodiment of the invention the flat optical element could also be specialised filters which is exchangeable.

Improvements to the basic system 1 . Camera Mounts

The protector could be made for any camera mount type, but would also be able to mix mount types. For example, on the camera side a Canon EF™ mount can be used while the other side may offer the possibility to utilise Nikon™ lenses of the Al mount type. This protector could thus be a dust problem solver as well as providing a lens interchanging utility. Signal conditioning would be needed when non-specific lenses are used and this would need to be included in the dust protector.

2. Software and Lens interchange ability

As with item 1 , different lenses could be utilised and this opens up the opportunity for software upgrades in the cameras to utilise the different lenses. Compatibility issues could thus be overcome.

3. Inclusion of filters

In the basic form, the clear Optical flat' could be replaced by a filter element. A UV, polarizer or neutral density filter or any other suitable filter could be implemented. The optical corrected protector (20) could also feature filter elements to protect and enhance the overall system. As shown in Figure 4, a screw type filter (21 ) of the protector (20) could easily be removed and replaced with another filter suitable for the next shot. Other arrangements could also be possible like a spring loaded filter system that can be changed from the top etc. This filter arrangement would greatly reduce the cost of filters as they would be of a single size and would eliminate the requirement of a filter for each size lens.

It will be appreciated that with a protector according to the invention secured to a camera, the sensor or film of a camera would require cleaning much less often and dust accumulation inside the body of the camera may never be a problem at all.

It would be possible to clean the dust protector with normal lens cleaning equipment usually used by photographers and no special requirement would be needed to clean the system. The dust protector thus provides a very cost effective way of keeping the sensor of a camera clean.

If dust is detected on photographs, the lens can be removed and the front optical elements cleaned. In contrast, if the sensor is dirty no quick fix exists and a very clean environment would be required to clean the sensor (this often done by professional in controlled

conditions). The presence of such dust may thus at least reduce the quality of photographs taken.

The dust protector makes provision for the inclusion of filters in the system. This inclusion of filters would mean that specific filters would not be required for each lens as it would form part of the dust protector. Thus a single size filter of comparative small size is required for the use with all the lenses of a photographer. The photographer would thus be able to buy a higher grade filter due to the fact that he only requires one for all his lenses.

The design of the dust protector is not limited to the inclusion of only one removable filter but might include the option for multiple filters as required by the photographer.

The design of the filter system is also not limited to a screw type filter, which would require that the filter could only be changed when the lens is removed, but could include any type of filter arrangement to change the filters from the outside as well. For example, one or more slots could be provided in the dust protector to slide filter elements in and out of the dust protector, without removing any lenses. These slots would be covered by a dust cover to ensure that the system is dust proof when in operation. The filter/s will preferable be on the lens side to ensure that the optical elements would still protect the camera from any dust ingress.

3. Optical Elements

The main objective of the optical elements is to correct the focal length. However, a further objective could also be achieved.

The optical elements could also function as a converter to change the effective focal length of the attached lens. This type of converter is named differently by various manufacturers for example: Tele-converters, Extenders, Multipliers etc. For the sake of this specification this will be referred to as a converter.