GB2266782A

GB2266782A - Soft focus filter

Info

Publication number: GB2266782A
Application number: GB9208366A
Authority: GB
Inventors: Ron Vickers
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-04-16
Filing date: 1992-04-16
Publication date: 1993-11-10
Also published as: GB9208366D0

Abstract

A soft focus filter comprises an optically flat material having a plurality of holes 1 with a convex or concave lens 2 around each the edge of the hole. Any pattern can be determined by the placement and number of holes with surrounding lenses. The hole in the centre of the lens controls the strength of the lens, maintains good contrast and a focus shift image. A perfectly focus shift free sharp image and an out of focus image is superimposed upon the recording medium at the same time which can be enlarged to any size and still maintain good resolution whatever the size. <IMAGE>

Description

I Ron Vickers of 347 Leeds Road, Nelson, Lancs, a British subject do hereby declare the invention for which I pray that a patent be granted and the method by which it is performed to be particularly described in by the following statement.

The invention relates to filters designed to control the softening of an image formed by a lens on to the film plane or imaging plane, hereafter called the Focal Plane, of a camera or image recording device hereafter called an image recording device.

Existing filters fall into two categories: A) Those that soften the image by degrading the whole image.

B) Those that soften the image by using various small lenses of different focal lengths or other diffusing material or irregularities designed to interfere with light transmission in an irregular or regular pattern on a flat clear optical surface in a manner which leaves parts of the surface unaffected. This causes a sharp image with an out of focus or diffused image to be superimposed upon the recording surface simultaneously.

For portraits of people filters which fall in category B as above are generously prefered.

The most popular of category B filters are those with a variety of small lenses formed in an otherwise flat surface but there vare two problems with those devices.

i) The introduction of a thick glass element used to make the filters alters the contrast characteristics of the lens used in the camera.

ii) Because of material flow around the indentations in the mould and the cooling process, distortions and small irregularities occur in the flat surface surrounding the lens and this causes slight focus shift and some distortion in the sharp part of the image.

This invention minimises these problems and is as follows: A flat optical surface is pierced all the way through with a number of small holes, the rim of each hole is surrounded by an concave or convex lens of regular or irregular focal length.

Light from the subject which passes through the hole and through the lens of the image recording device forms a perfectly sharp image of the same contrast characteristics as the image recording device lens. This assures that there is a perfectly sharp image formed without focus shift regardless of any irregularities in the flat surface of the filter and the alteration in the contrast characteristics caused by the material used is minimised.

The light from the subject which passes through the lens surrounding the rim of the hole forms an out of focus image upon the focal plane at the same time as the sharp image.

The size and number of holes used and the strength and shape of the lenses surrounding the rim each hole will depend upon seven factors.

The strength of the effect required.

The focal length of the imaging device lens.

The aperture of the imaging device lens.

The size of the imaging area (focal plane).

The area of softness required.

The other softening devices incorporated into the filter design.

The restrictions dictated by the manufacturing process.

Claims

The main claims of the patent are as follows:

1) That a hole through an optical filter with a lens of any type with a regular or irregular focal length surrounding the rim of the hole results in a sharp image of the same contrast characteristics as the camera lens and a soft out of focus image being formed simultaneously at the same time at the focal plane of the imaging device.

2) That any number of these holes with a lens surrounding the rim of the hole can be used to manufacture a softening device for image recording.

3. A filter with lenses inserted which sorround a hole the hole controls the degree of strength of the lens and maintains the focus shift image and contrast.

3) That these holes with a lens surrounding the rim can be used with other softening methods in the same item to produce a required softening device.

Amendments to the claims have been filed as follows 1. A soft filter capable of putting a SHARP FOCUS SHIFT FREE image an to the Recording Medium of a CAMERA when placed in front of the lens.

2. A filter that can control the degree of softness buy inserting any amount of lenses into an optical flat material without effecting the flatness of the material.