A video signal combining apparatus comprising: a video signal processing unit which is adapted to combine an output video image stream from first and second input image streams by dividing an image area of an image of said output video image stream into two regions (15, 16) and applying to said first region image information extracted from said first video image stream and applying to said second region image information extracted from said second input video image stream, and a first video camera having an image sensor that transmits said first input image stream to the video signal processing unit and a second video camera that transmits said second input image stream to the video signal processing unit, each camera having a viewfinder for displaying at least one of said input and output video image streams, and wherein the video signal processing unit is adapted to generate the combined output video image stream in an intermediate phase of a wipe procedure, at the beginning of which the output video image stream is identical to one of said input video image streams and at the end of which it is identical to the other one of said input video image streams, characterized in that the viewfinder of one of the first and second video cameras (1,2) is adapted to display a moving border between said first and second regions (15, 16) superimposed upon an image which is currently being taken by the respective video camera at a time prior to the wipe procedure to estimate the effect of the wipe procedure and to return to the image that is currently being taken by the respective video camera when the moving border has moved across the entire viewfinder screen. a video signal processing unit which is adapted to combine an output video image stream from first and second input image streams by dividing an image area of an image of said output video image stream into two regions (15, 16) and applying to said first region image information extracted from said first video image stream and applying to said second region image information extracted from said second input video image stream, and a first video camera having an image sensor that transmits said first input image stream to the video signal processing unit and a second video camera that transmits said second input image stream to the video signal processing unit, each camera having a viewfinder for displaying at least one of said input and output video image streams, and wherein the video signal processing unit is adapted to generate the combined output video image stream in an intermediate phase of a wipe procedure, at the beginning of which the output video image stream is identical to one of said input video image streams and at the end of which it is identical to the other one of said input video image streams, characterized in that the viewfinder of one of the first and second video cameras (1,2) is adapted to display a moving border between said first and second regions (15, 16) superimposed upon an image which is currently being taken by the respective video camera at a time prior to the wipe procedure to estimate the effect of the wipe procedure and to return to the image that is currently being taken by the respective video camera when the moving border has moved across the entire viewfinder screen.