US793932A - Device for timing photographic exposures. - Google Patents

Description

No. 793,932. PATENI'ED JULY 4,1905. J. T. HODGBS. DEVIGB FOR TIMING PHOTOGRAPHIG' EXPOSURES.

APPLICATION FILED JUNE 6. 1904.

JOHN Tllt lOTHY ll ODtlES,

lUlEVlltitllE F'Ultt Tlllt llllhltili Patented July 1, ll-905.,

SPECIFICATION forming part of Letters Patent No. 793,932, dated July 4, 1905. Application filed June 6, 1904. Serial No. 211,381.

To all 10/1/0171 it 'm/rw concern:

Be it known that 1, JOHN Tino'rnir l lo 1o as, a citizen oi. the United States, residing at Roclqiort, in the county oi Spencer and State of Indiana, have invented. a new and useful. Device for Timing Photographic Exposures, cl. which the following is a specification.

it is customary in making photographic exposures to time the latter in accordance with the shadows surrounding and upon the image irrespective of the high lights, and in order that a clear sharp picture may be produced it is imperative that the exposure of the sensitive plate or lilni be continued until there is reproduced upon the latter any and. all. details which may exist in the deepest shadows.

My invention has for its objects to produce a comparatively simple inexpensive device bywhich the requisite time for exposures may be readily and accurately determined to thus produce clear sharp i'iegativcs and one which may be cilectively employed as a focusing glass or instrument.

To these ends the invention comprises the novel features of construction and combination of parts more fully hereinafter described.

in the accompanying drawings, liigure l. is a perspective view of a device embodying my invention. Fig. 2 is a vertical longitudinal sectional elevation through the same. Fig. 3 is a detail perspective view of the shal' t, timing members, and partitions removed from the casing. Fig. l is a view similar to Fig. 1 of the device as seen from the opposite side.

Referring to the drawings, 1 designates the casing as a whole, comprising a pair of end n'iembers or heads 2 3 and a tubular shell 4L, constituting the outer wall and into which the heads are seated, the parts being 1naintained. in assemblage by means of a central belt or shaft 5, preferably square or of other non-circular form in crosssection, while the head. 2 is provided between its center and margin with an annular intern ally-threaded opening 6 in. axial alinement witha simi la rbut somewhat larger opening 7 formed in. the head 3, this latter opening being surrounded by an outwardly-projecting extcrnally-threaded flange 8.

Tapped into the threaded opening 6 is a tubular focusing member or section 5), carryi ng upon. its interior and adjacent to its inner end a biconvex magni'liyingdens 10, arranged concentric 0.1. an outwardly-llaring conical locusing member or tube 11, tapped. onto the externally-threznled 'llange S and oil. which the tube 9 forms, in c'll'ect, a contimiation.

Housed within the casing l a plurality of timing members or disks 12 13 14. 15, spaced. one from another and. having interposed therebctween relatively thin division-plates or partitions 16, which are mounted directly upon and prevented from rotation by the noncircular shaft 5, the timing members being, however, rotatable upon suitable l.)caring sleeves or collars 17, in turn fixed upon andv against rotation by the shaf it being apparent from this arrangement that the disks are free [or independent rotation and are prevented from contact one with another by means of the partitions 16, whereby liability of one disk being accidentallyrotated through frictional contact with. another is wholly obviated. Each partition 16 has formed therein an annular opening 18, the opei'iings .in the respective partitions being in axial alinement with one another and with the openings 6 7, while in each. of the rotary timing-disks there is formed a pair of annular openings 19 20, preferably arranged as shown in Fig. 3 and. of a diameter corresponding to that oil the openings 18, in register with which latter either'of the openings 19 20 may be brought at will by partial rotation of the disks, which for this purpose are provided. each with a linger piece or pin 21., projecting radially from the periphery of the disk through one of a series of slots or guides 22, provided in the wall 4 of the casing. The guide-slots, which obviously correspond in number to the number of disks, are of such length that when the pins 21 come in contact with. and are brought to rest by the opposite ends of the slot one or the other of the openings 19 20 in the disks will be in proper register with the openings 18. Thus the pins and slots constitute means for limiting the rotation of the disks and for determining the registration. of the openings. Each of the disks carries within its opening 20 a translucent sheet or filling 23, of glass or other suitable material, said sheets in the respective disks being of relatively varying degrees of translucency or opacity, proportionately increasing in density from the outermost disk 12 toward the innermost disk 15, the glass 23 of the disk 12 being, for instance, of one degree of density, that of the disk 13 two degrees, of the disk 1 L four degrees, and of the disk 15 eight degrees.

In practice when it is desired to ascertain the time necessary for an exposure the outer end of tube 11 is placed against the objectglass at the back of the camera immediately over the image reflected thereon, and the disks are manipulated for bringing certain ones or a sufficient number of the translucent sheets a3 into play for neutralizing the lights and shadows in the image until the details of the latter are obscured or, that is, until the illumination of the shadows is practically de stroyed, and the number of degrees of opacity as represented by the translucent sheet or sheets thus brought into action permits a ready determination of the time required for the exposure. It is to be noted in this connection that the timing-disks may by bringing them into play singly or in different combinations have a scope of from one to fifteen degrees of density.

Provided upon the wall 4 of the casing is a scale 24, computed in accordance with the degree of opacity of the plates 23 and indicating the lengti of time necessary for exposures wherein the shadows in the object being photographed are reduced to a loss of detail by the required degree of opacity of the plate or plates, it being apparent from this scale that the length of time required for the exposure gradually increases as the number of degrees of opacity of the sheet or sheets brought into play decreases or, that is, as the strength of the high lights decreases and the depth of the shadows increases.

It is apparent from the foregoing that I produce a comparatively simple inexpensive device admirably adapted for readily and accurately timing exposures and one which may by moving the disks to throw their plates 23 out of action and bringing their openings 19 into register be employed as a focusingglass. In attaining these ends it is to be understood that I do not limit or confine myself to the precise details herein set forth, inasmuch as minor changes therein may be resorted to without departing from the spirit of the invention, it being obvious, among other changes, that the number of disks employed and the degree of translucency of the plates 23 may be varied at will.

Having thus described the invention, what is claimed is- 1. In a device of the class described, a casing subdivided into a plurality of compartments and provided with a sight-opening, a

plurality of movable members inclosed within the respective compartments of the easing and having translucent portions adapted to be brought into line with the sight-opening, means for limiting the movement of the members in either direction, and a focusing lens arranged within said sight-opening.

2. In a device of the class described, a casing having partitions therein forming simi lar compartments, said casing having a sight opening alining with openings in the partitions, and a plurality of guide-slots, a plurality of independently-rotatable members inclosed within the respective compartments of the casing and each having a translucent portion and an opening adapted to be brought, respectively, into line with the sight-opening, and means carried by the members and working, respectively, in the guide-slots for operating said members, said means being adapted to contact with the ends of the slots for limiting the movement of the members in either direction when the openings or translucent portions thereof are in alinement with the sight-opening.

3. In a device of the class described, a closed casing having detachable end walls and provided with a sight-opening, a shaft extending through the casing and engaging the end walls thereof, stationary partitions carried by the shaft and each provided with an opening in alinement with the sight-openi a plurality of movable members rota tably mounted on the shaft between the partitions and having translucent portions adapted to be brought into line with the sight-opening, and a lens arranged within said sightopening.

4. In a device of the class described, a closed casing having detachable end walls and provided with a sight-opening, a squared shaft extending through the casing and engaging the end walls thereof, partitions arranged within the casing and provided with squared openings for the reception of the shaft and each provided with an opening in alinement with the sightopening, a plurality of movable members mounted on the shaft between said partitions and provided with translucent portions of different degrees of opacity, said translucent portions and openings being adapted to be brought, respectively, into line with the sight-opening.

5. In a device of the class described, a closed casing having detachable end walls and provided with a sight-opening, there be ing a plurality of guide-slots formed in the side walls of said casing, a shaft extending through the casing and engaging the end walls thereof, stationary partitions mounted on the shaft and each provided with an opening in alinement with the sight-opening, a plurality of members rotatably mounted on the shaft between the partitions and having translucent portions adapted to be brought In testimony that I claim the fel'egtnng as my own I have hereto altixed my signature in the p.1.'esenee of two witnesses.

JOHN 'lIMOTHY HOD GES.

Witnesses Anei 1: STEVENSON, 15-11mm Cnmvnjicn.

tiransiueent iiortions thereof are in alineinent with. the sight-opening, end. at bleenvexiens arranged within. Silld sight-opening.

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