Optical: systems and elements – Prism – With reflecting surface
Patent
1992-02-26
1994-10-18
Blankenship, Howard B.
Optical: systems and elements
Prism
With reflecting surface
354286, 359823, 359830, G03B 118
Patent
active
053572998
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a conversion arrangement for mounting optical units on cameras, particularly though not exclusively on film or television cameras.
When using optical units on modern cameras it is desirable to retain the desired focusing and iris functions of the optical units.
SUMMARY OF THE INVENTION
The present invention seeks to provide a conversion arrangement for mounting optical units on cameras.
Accordingly, the present invention provides a conversion arrangement for coupling an optical unit to a camera body, the conversion arrangement comprising:
a mounting means for attachment to the camera body;
a generally cylindrical carrier for attachment to said optical unit, said carrier being coaxially coupled to said mounting means for axial movement relative thereto:
a focusing ring coaxial with and coupled to said mounting means and said carrier for rotation relative thereto wherein rotation of said focusing ring causes said carrier to move axially of said mounting means for focusing said optical unit; and
means biassed into radial engagement with said focusing ring for inhibiting axial movement of said focusing ring relative to said carrier in the absence of rotational movement of said focusing ring relative to said carrier, said inhibiting means being operable to control axial movement of said carrier during rotation of said focusing ring.
Preferably the inhibiting means comprises guide means engaged in a screw-threaded manner with said focusing ring and secured against axial and rotational movement relative to said carrier so as to guide said carrier axially of said focusing ring on rotation of said ring; and wherein said guide means is biased radially of said carrier into positive screw-threaded engagement with said focusing ring to inhibit axial movement of said focusing ring relative to said carrier in the absence of rotational movement of said focusing ring relative to said carrier.
BRIEF DESCRIPTION OF THE DRAWING
The present invention is further described hereinafter by way of example, with reference to the accompanying drawing which is a longitudinal section through a conversion arrangement according to one embodiment of the present invention with parts omitted for clarity.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawing, this shows a section through a conversion arrangement 10 which is intended for use with a 32 mm Cooke Speed Pancro optical unit, although it will be appreciated by those skilled in the art that the invention is applicable to other forms of optical units. The conversion arrangement enables the optical unit to be mounted on to a camera such as a film or television camera (having in this example a PL format). The conversion arrangement is fitted within the camera body, which is to the left as seen in the drawing, whilst the optical unit is contained within the conversion arrangement, facing to the right.
The conversion arrangement 10 comprises a mounting means or member A, a carrier or optical unit support B, a focusing gear C, and an iris drive gear D.
The mounting member A is dimensioned so as to fit on the front of a camera body and has a mounting adaptor 12 of suitable form and a mounting body 14. The adaptor 12 engages with the mounting arrangement on the camera to secure the conversion arrangement 10 in position. The mounting body also has an annular recess 18 which opens axially away from the camera body to receive a radially inwardly extending flange 20 of a focusing ring 22. The flange 20 is formed at the camera body end of the focusing ring 22 and is retained in the recess 18 by the action of a thrust ring 24 and retaining ring 26, this being described further below.
The optical unit support B is co-axially mounted within the mounting member A so as to be axially slidable relative thereto but is prevented from rotating relative to the mounting member A.
An annular extension 28 of the optical unit support B is provided with a radially outer annular groove in which two tenon
REFERENCES:
patent: 2254537 (1941-09-01), Nerwin
patent: 2529894 (1950-11-01), Altman et al.
patent: 4506952 (1985-03-01), Grollimund
Blankenship Howard B.
Van Diemen Films Limited
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