GB2396021A

GB2396021A - External Viewfinder for a camera

Info

Publication number: GB2396021A
Application number: GB0228154A
Authority: GB
Inventors: Allan Charles Waite
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-12-03
Filing date: 2002-12-03
Publication date: 2004-06-09
Also published as: GB0228154D0

Abstract

An external viewfinder on which a camera (18) can be mounted comprises an extension arm (10), a viewing frame (11), a camera mount (12), a securing bolt (13) and a locating ridge (14). The viewfinder is constructed in such a manner that when the camera is attached, the view (19) within the viewing frame when placed on or close to the subject to be photographed will be a precise match to the photograph taken. The viewfinder also has studs for attaching a cross-sight. The frame is hinged to the arm to allow it to be folded flat.

Description

a' A. 1 239602 1

EXTERNAL VIEWFINDER FOR A CAMERA

This invention relates to an external viewfinder for a camera.

Most modern 35mm and digital cameras are small compact and easy to use, however unless they are of the Single Lens Reflex type photographers have to allow for parallax. This is because the cameras lens is offset from the cameras viewfinder by about an inch and a quarter. Parallax is not a problem when photographing subjects at a distance of three feet plus - a one-inch offset in three feet is proportionately slight.

But at closer distances the offset can mean that the photographers view is significantly different from that of the camera, hence any photograph taken will not be as viewed by the photographer. Compact 35mm cameras do not usually fit or have alternative lenses with a focal length of less than three feet because of this problem. However digital cameras now have 'macro' lenses with a focal length of about six inches, and at this sort of distance are greatly affected by parallax.

Unless expensive equipment is purchased even the more complex Single Lens Reflex Camera can have two problems when taking close up photographs. 1. Access in a confined space where the photographer is unable to look through the cameras viewfinder. 2. The ability of a second party - who may be commissioning the photograph to guide the photographer to capture the exact image they want.

According to the present invention there is an external viewfinder that can be attached to the tripod mounting fitted to most modern cameras. This external viewfinder when attached to the camera it is specifically designed for will provide a rectangular viewing frame set at a predetermined focal length. The aperture of this viewng frame will be fractionally larger than the field of view of the camera lens. The viewing

frame will be aligned on a plane that is horizontally and vertically parallel to the lens, and the centre of vision of the lens will pass through the centre-point of the viewing frame. A centre-point that can be defined if needed by cross-sights strung across studs at the corner of the frame.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows in perspective the viewfinder Figure 2 shows in perspective the viewfinder with camera attached and lines of vision from the camera lens to the inside corners of the viewing frame.

Figure 3 shows a line drawing illustrating an example of relative positions of the photographer's line of vision, camera and viewfinder, when taking a photograph on a level plane.

Figure 4 shows a line drawing illustrating an example of the relative positions of the photographer's line of vision, observer's vision, camera and viewfinder when taking a photograph on a vertical plane with access to the internal viewfinder restricted.

Referring to the drawing the external viewfinder comprises of an extension arm 10 a viewing frame 11 a camera mount 12, a securing bolt 13 locating ridge 14. Studs 15 and cross-sight 16. If desired a hinge and securing catch could be provided at 17 to allow the viewfinder to fold flat.

Figure 2 shows the camera 18 attached accurately to the camera mount 12 (Figl) of the external viewfinder by means the locating ridge 14(Figl) and of a bolt 13 (Figl) screwed into the camera tripod mounting thread. The surface of the camera mount 12 is set at an angle so as to allow an uninterrupted field of vision to the aperture within

the viewing frame 11. This field of vision being defined by lines 19. The angles where

the viewing frame 11 is fixed to the extension armlO are designed at an angle that keeps viewing frame 11 and camera 17 parallel in both planes. The frame 11 is also attached to extension arm 10 so that the line of central vision 21 of the camera lens 22 passes through centre point 20 of the viewing frames 11 aperture.

Figure 3 shows a photographer's point of vision 23 and his field of vision 24

uninterrupted by the camera 18 taking a photograph with the aid of the external viewfinder. Fig 4 shows a situation were the conventional site 26 of an internal viewfinder gives a photographer difficult or impossible access if that viewfinder had to be used. It also shows a second viewer 25 can observe the area of object 27 being photographed if an external viewfinder is used.

With the camera attached (Fig 2) the photographer can if desired attach a cross-sight 16 of say cotton wound round studs 15. With adjustments particularly with regard to focal length made to the camera 17. The photographer (Fig4) then lightly places the frame on the surface to be photographed with the exact area to be photographed and presses the shutter realise. 21

Claims

1. An external viewfinder for a camera comprising of an extension arm, a viewing frame with studs to attach a cross-sight, a camera mount with securing bolt and locating ridge, and a hinge to allow the viewfinder to fold flat. The viewfinder being constructed in such a manner that when a camera is attached to it the area defined by the aperture formed by the viewing frame will accurately depict the photograph taken by that camera on a plane level with that frame.

2. A viewfinder as described in Claim 1 will allow for parallax inherent in a camera.

3. A viewfinder as described in Claim 1 that will have known distances between the plane of the viewing frame and the camera lens.

4. A viewing frame as described in Claim 1 that can be placed on the subject to be photographed, the resulting area framed being in easy view of the photographer from various distances and angles.

5. A viewing frame as described in Claim 1 that a second party can also look at the area to be photographed.

6. A viewing frame as described in Claim 1 will when placed on a stable surface on which the subject is lying or placed will provide a camera steady.

7. A viewing frame as described in Claim 1 will in the case of restricted accessibility possibly allow accurate photographs to be taken where movement of the subject might involve legal, medical, forensic or religious issues, or might result in the damage of that subject.

8. A viewing frame as described in Claim 1 can by its ability to be placed accurately at a future date, can, with referral to a previous photograph be used in time lapse photography.

9. A viewing frame as described in Claim 1 that can be compact and portable.