WO2007006241A2

WO2007006241A2 - Circular flashlight extension

Info

Publication number: WO2007006241A2
Application number: PCT/CZ2005/000060
Authority: WO
Inventors: Dalibor Zyka
Original assignee: Short Images S.R.O.
Priority date: 2005-07-13
Filing date: 2005-08-10
Publication date: 2007-01-18
Also published as: WO2007006241A3; CZ2005448A3

Abstract

The circular extension (1) to diffuse flashlight consists of a double hollow cylinder with the inlet opening (5) in the back wall (3) to mount the head (6) of an external flashlight (15) on a camera (16) in the direction of the central axis (7) of the extension (1). Opposite to the inlet opening (5) there are at least two reflecting surfaces (9, 10) reflecting the light into the extension (1) on both sides of the inlet opening (5). The light goes through the diffuser (4) outside. A light-guiding ring (11) inside the extension (1) improves the transmission of light. A size adaptor (20) on the inlet opening (5) enables its universal use for various flashlights (15).

Description

Circular Flashlight Extension

Background and summary of the invention

This invention concerns the circular extension to diffuse flashlight when taking photographs.

Circular camera flashlights, i.e. flashlights with a circular discharge tube, to achieve the so-called soft light illumination, i.e. illumination without marked shadows, have been known for long. The disadvantages of these special devices consists in the fact that circular discharge tubes are relatively expensive, little resistant against crash and they usually use higher voltage then available from the grid and therefore they require separate generators or adapters. This makes a classical circular flashlight an awkward, bulky, fragile and expensive device.

According to the Czech author's certificate No. 221 782 titled ..Reflecting ring to diffuse discharge from a classical flashlight into a circular area around the camera lens " (by MUDr. Petr Cuban, application date 22 July 1981, PV 5566-81") a circular flashlight extension has been known in form of a double hollow cylinder made up of an outer and inner jacket of the same height, with the back wall of the hollow cylinder formed by a flat annular ring. The inner surface of the extension is provided with reflecting layers, mutually passing into one another.

The outer jacket of the double hollow cylinder is in the upper part of the perimeter provided with an opening for a flashlight discharge tube, covered with a rectangular transparent cap, and with a detachable socket with fasteners to hold (an external) flashlight. The extension also contains a threaded collar to attach it to a camera. The front annular section of the double hollow cylinder consists of a front transparent cap (diffuser). The described circular extension serves as an adapter to the classical external flashlight, commonly used in the past, and it diffuses its point light into a circular area. The flashlight is attached to the extension perimeter tangentially and the extension itself is mounted concentrically on the camera lens. The flashlight discharged into the opening in the outer jacket, perpendicularly to the extension axis, lights up the ballotini glass grains of the reflecting layers. Ballotini grains influence one another with light induction and the entire reflecting surface lights up evenly as a result. This multiple reflected and diffused light is directed by the arrangement of reflecting layers in parallel with the optical axis of the camera lens.

Disadvantages of the described circular extension consist in the fact that its efficiency is very low as multiple reflection, refraction and diffusion of light on the individual ballotine grains extremely reduce the outlet intensity of light, so it would be necessary to use very powerful flashlights for common photographic purposes, e.g. studio photography. Moreover, the chromatic spectrum of the used light sources changes as a result of multiple refraction, which is an undesirable phenomenon. The application of the described extension is limited to the so-called macrophotography taken from a very close distance and to external flashlights separated from a camera which may be mounted tangentially on the circular extension.

The device cannot be use for the current, mostly digital cameras, with external flashlights on the camera which are in parallel with the lens and thus cannot be mounted tangentially on the circular extension. The device also in no way eliminates the issue of flashlight different sizes.

A similar solution of the circular extension for macrophotography is described in the German patent application DE 10146158. A circular acrylate extension is arranged concentrically around the lens, the light from a built-in flashlight enters axially through an opening which overlays the discharge tube of the built-in flashlight and reflects on the slanted lateral surface inside the double hollow cylinder, where it again uses reflecting layers to emit light around the lens. The described solution partly addresses some disadvantages of the extension mentioned above, particularly when it comes to attaching to a camera with a built-in flash, but its emission efficiency is still insufficient for common studio photography. The low efficiency is -J-

caused by the lateral slanted reflecting surface, which insufficiently reflects light inside the annular space.

The purpose of the invention is to find a circular extension which would create a circular soft flashlight of sufficient intensity, not only for macrophotography, but particularly for amateur and professional photography of large objects, both indoors and outdoors, and which could be directly used on cameras provided with an external flashlight on the camera body, and adapted for mounting on flashlights of various sizes.

The mentioned disadvantages are completely eliminated by the circular flashlight extension under this invention. The extension consists of the previously known double hollow cylinder with a front diffuser made of transparent material, and an outer jacket, inner jacket and back wall made of non-transparent material, preferably provided with a reflecting layer inside. The back wall of the extension is provided with an inlet opening for the flashlight in the central axis direction. The subject matter of the invention consists in the fact that opposite to the inlet opening, whose shape is adapted to tightly mount the flashlight head, the extension is inside provided with at least two reflecting surfaces forming a closed angle between each other. The angle apex is situated in the projection of the extension central axis at the inlet opening and the angle legs open toward the front diffuser so that each reflecting surface is slanted against the extension interior on both sides of the inlet opening.

In one advantageous realization of the invention the reflecting surfaces form a reflecting body whose width is equal or smaller than the width of the inlet opening.

Advantages of the solution under this invention consist particularly in the fact that the circular extension can be mounted on cameras with an attached external flashlight, whose head is parallel to the camera lens, and particularly in the fact that the arrangement of reflecting surfaces enables optimized distribution of light into the extension and its emission through a diffuser with minimum losses and so the extension can be used even for flashlights of usual power to take photographs of large objects, both indoors and outdoors.

Another advantageous realization features a ring made of light-guiding material inside the extension, interrupted in the sections of reflecting surfaces, with the ring ends in the interruption area oriented opposite to the reflecting surfaces. This realization further supports light transmission into the extension with the light emitted by the ring inside the extension.

Another advantageous realization features the ring made of a non-circular profile, containing at least one emission surface oriented towards the diffuser. This realization means a greater ratio between the light emitted by the ring towards the diffuser and the light emitted to other parts of the extension. It is advantageous to make the ring of acrylate and to grind and polish surfaces of its ends and emission surface in order to achieve the optimum inlet and outlet of light beams without refraction and losses.

It is also advantageous to provide the circular flashlight extension under this invention with a size adapter at the inlet opening side, which exceeds the outer wall perimeter and enables to mount flashlights with large-size heads. The adapter includes at least one reflecting surface, which forms a closed angle with the central axis of the extension and is situated above reflecting surfaces of the extension in order to transmit light from the upper part of the head into the extension. To improve the transmission it is advantageous for the contact line of the reflecting surfaces in the extension to form a closed angle with the extension central axis as well.

Finally, it is advantageous for the size adapter to be attached to the extension in a dismountable manner and thus to become an accessory to any external flashlight. The circular flashlight extension under this invention enables fast and universal use of soft flashlight illumination when taking photographs indoors and outdoors, by simply mounting the extension on the flashlight head. The light losses resulting from transmission and emission through the transparent diffuser are minimum and may be adjusted by setting up the camera corrections, so that with such compensation exposure meters built-in the camera can be commonly used even when taking photographs with the circular extension.

The design of the circular extension is simple, easy to manufacture, lightweight and financially affordable for most professional and amateur photographers.

Brief description of the Drawings

The invention will be explained in detail with drawings; Fig. No. 1 is a view in the central axis direction of the extension back wall with an attached flashlight head on the camera, Fig. 2 is a ground projection of the extension under Fig. 1, Fig. 3 is a cross-section of the same extension in the A-A plane without the flashlight and camera, Fig. 4 is a view of a back wall of the extension with a ring made of light- guiding material, Fig. 5 is a cross-section of the extension under Fig. 4 in the B-B plane, Fig. 6 is a cross-section of the extension under Fig. 4 in the C-C plane, Fig. 7 is a view of a back wall of the extension with a size adapter and Fig. 8 is a side projection of the extension under Fig. 8.

Detailed description of the preferred embodiments

It is understood that specific examples of realization of the invention, as described and depicted below, are provided only as an illustration and that they in no way limit realization of the invention to such examples. Experts proficient in the state of the art will find and will be able to identify through routine experimenting one or more equivalents of the realizations of the invention as specifically described herein. Such equivalents shall be covered by the scope of patent claims contained herein.

The first example of realization of the invention, shown in Figures 1 through 3, consist of a circular extension 1 to be mounted on a head 6 of an external flashlight .15 for a camera 16. The extension 1 is made of plastic in form of a double hollow cylinder. A front diffuser 4 is made of transparent acrylate and may be detachable, i.e. it is attached to the extension 1_ in a dismountable manner. An outer jacket 2, inner jacket 2'and the back wall 3 are made of black non-transparent plastic and on the inner walls forming the inside of the extension 1 they are provided with a reflecting layer 17 made of thin bright sheet. A cross section of the extension 1 may be square, rectangular, trapezoidal, elliptic or of other suitable shape. An inlet opening 5 to mount the head 6 of the external flashlight 15 is created in the back wall 3 and its shape is adjusted to fit the shape of heads 6 of most flashlights 15. Inside the extension I₁ opposite to the inlet opening (S₁ there is a reflecting body 8 whose two reflecting surfaces 9_and 10 form a closed angle g between each other and are slanted against the interior of the extension 1 on both sides of the inlet opening 5 so that the apex of the angle αjs closer to the inlet opening 5 and its legs open toward the front diffuser 4. When the circular extension 1 is to be used the inlet opening 5 holds the head 6 of the external flashlight 15 with the camera 16 so that the camera V5 is approximately in the center of the circular extension 1 and it is arranged coaxially with the front diffuser 4. The glaring light of the flashlight 15 is reflected on reflecting surfaces 9 and 10 evenly into each part of interior of the extension 1 on both sides of the inlet opening 5, where it further reflects on reflecting layers 17 and is emitted outside already as soft light diffused by the diffuser 4. In the second example of realization of the invention, shown in Figures 4 and Fig. 5, the extension 1 is additionally provided with an interrupted ring H made of light guiding material, in this particular case of acrylate. The ring H is placed inside the extension 1, closer to the diffuser 4, and its grinded and polished ends Xλ and 13 are oriented opposite to the reflecting surfaces 9 and 10, from which the light enters the ring H and the ring H further emits the light into the extension 1 and through the diffuser 4 outside. To improve efficiency of emission the ring H is provided with a grinded and polished emission surface 14 oriented towards the diffuser 4, as shown in Fig. 6. Instead of the reflecting layer 17 on the wall a reflecting parable 18 may be used alternatively, situated behind the ring YL Fastening of the ring H inside the extension 1 may be executed in different manners, e.g. on supports 19, as shown in Figures 5 and 6, but also using various not depicted recessions or freely prestressed, basically anywhere inside the extension 1.

Figures 7 and 8 demonstrate the third example of realization of the invention, which may be combined with the first two examples presented above. The inlet opening 5 is enlarged with a detachable size adapter 20, made of non-transparent plastic and mounted on the outer wall 2. The adapter 20 has a reflecting surface 21, forming with the central axis 7 a closed angle §, and situated above the reflecting surfaces 9 and IQ, to reflect light on them from the upper part of the head 6 of the flashlight Ij5. To improve distribution of light into both the interior parts of the extension 1 also the contact line 22 of the reflecting surfaces 9 and 10 is slanted to the central axis 7 of the extension I₁ forming a closed angle y_. The detachable adapter 20 can be made depending on specific dimensions of the head 6 of each flashlight 1j5 on the market, while the basic body of the circular extension 1 is universal in terms of its dimensions and can be used for nearly any type of flashlights 15 and cameras 16.

The circular flashlight extension under this invention can be used particularly to diffuse light for photography purposes, both indoors and outdoors.

Claims

1. The circular flashlight extension in form of a double hollow cylinder with a front diffuser made of transparent material and with an outer jacket, inner jacket and back wall made of non-transparent material, preferably provided with a reflecting layer on the inner surface, while the back wall is provided with an inlet opening to bring in the flashlight in the direction of the central axis, characterized by having inside the extension (1) and opposite to the inlet opening (5), whose shape is adjusted to tightly hold a flashlight head (6), at least two reflecting surfaces (9, 10) forming between them a closed angle (α), whose apex is in the projection of the central axis (7) of the extension (1) at the inlet opening (5), and its legs open toward the front diffuser (4) so that both the reflecting surfaces (9, 10) are slanted against the interior of the extension (1) on both sides of the inlet opening (5).

2. The circular flashlight extension according to claim 1, characterized by the reflecting surfaces (9, 10) forming a reflecting body (8), whose width is equal or smaller than the width of the inlet opening (5).

3. The circular flashlight extension according to claims 1 or 2, characterize d by having inside the extension (1), between the outer jacket (2), inner jacket (2^'), back wall (3) and diffuser (4), a ring (11) made of light-guiding material, interrupted in the sections of reflecting surfaces (9, 10), with its ends (12, 13) in the interruption area oriented opposite to the reflecting surfaces (9, 10).

4. The circular flashlight extension according to claim 3, cha racterized by the ring (11) made of a non-circular profile, containing at least one emission surface (14) oriented towards the diffuser (4).

5. The circular flashlight extension according to claims 3or4cha racteri- z e d by the ring (11) made of acrylate and having the surface of its ends (12, 13) and the emission surface (14) treated with grinding and polishing.

6. The circular flashlight extension according to at least one of the claims 1 through 5 characterized by having the inlet opening (5) provided with a size adapter (20) which exceeds perimeter of the outer wall (2) and contains at least one reflecting surface (21) forming with the central axis (7) of the extension (1) a closed angle (β), and situated above the reflecting surfaces (9, 10) of the extension (1).

7. The circular flashlight extension according to claim 6 ch aracte rized by the contact line (22) of the reflecting surfaces (9, 10) of the extension (1) which forms with the central axis (7) of the extension (1) a closed angle (v).

8. The circular flashlight extension according to claims 6or7characteri- z e d by having the size adapter (20) attached to the extension (1) in a dismountable manner.