Adapter between the front lens thread and the screwed-on photographic filter

Abstract

The invention relates to an adapter that is used between the front internal thread of photographic lenses, intended for holding filters, and photographic filters that are screwed onto this thread. The adapter allows the photographic filter to be screwed on easily, without jamming, and can be unscrewed again without the use of tools. This is achieved by means of recesses in the threads of the adapter, which reduce the contact area with the other threads and promote self-cleaning of the threads. Alternatively, the front-facing internal thread of the lens, intended for the attachment of photographic filters, can be equipped with the recesses according to the invention. This measure functionally replaces the use of the adapter according to the invention.

Description

Area of ​​application: The invention relates to a device for avoiding problems when unscrewing photographic filters that are screwed onto a lens by means of a screw thread. State of the art: Lenses used on cameras and video cameras typically have a screw thread for attaching optical filters. This thread is usually located on the front of the lens, just in front of the front element. The thread on the lens is an internal thread. The corresponding thread on the filter is an external thread. These threads come in various diameters. (see Appendix 1) Fig. 1) The internal thread on the lens and the external thread on the filter being used are the same size. For example, a filter with a 72mm external thread is screwed onto a 72mm internal thread. Since filters screwed onto a lens, especially wide-angle lenses, can cause additional vignetting, it can be useful to attach larger filters to smaller lens threads using their correspondingly larger filter threads. Filter adapters serve this purpose. For example, a filter adapter allows a filter with a 72mm male thread to be screwed onto a 67mm female thread. The filter adapter used in this case would have a 67mm male thread and a 72mm female thread. Disadvantages of the state of the art Filters that are screwed onto a lens or a filter adapter attached to the lens as needed should also be removable, i.e., unscrewed. The unscrewing process is often difficult. For example, even the smallest impurities in the filter thread, which are almost unavoidable in everyday photography, can cause the screwed-in filter to become stuck, jammed, and impossible or extremely difficult to remove manually. Often, it is necessary to loosen the filter. A stuck filter often requires suitable tools that are frequently unavailable on location. Furthermore, these attempts to remove the filter can damage both the internal and external threads. Potential problems include damaged threads, broken or scratched filters, and damaged lenses. Purpose of the invention: The purpose of the invention is to create a device that avoids or limits the aforementioned disadvantages of the prior art. The invention is intended to make it possible to easily and without problems screw photographic filters or filter adapters with their external thread onto the internal thread of another filter or lens, and in particular to screw them off again.

[0001] The objective of the invention is achieved as follows: 1. The adapter according to the invention is screwed onto the internal thread located on the lens. It then remains attached to the lens. This adapter has the following features: The adapter has an external thread, which allows it to be screwed onto the internal thread of the lens. On the other side, the adapter has an internal thread. This internal thread can be the same size as the external thread, or it can be larger. One or both of these threads, unlike threads used previously (according to the current state of the art), have the following design characteristics: The internal thread and / or the external thread each contain at least two recesses, or more than two recesses, which serve the following purposes: a) The recesses on the internal thread of the adapter according to the invention reduce the contact area between this internal thread and the external thread of filters screwed into it. This reduces the friction between the threads and reduces the forces required for screwing the filters in or out. (see Annex 1, Fig. 2) b) The recesses on the external thread of the adapter according to the invention reduce the contact area between this external thread and the internal thread onto which the adapter is screwed. This will generally be the internal thread on a lens intended for attaching filters. This reduces friction between the threads and thus reduces the forces required for screwing the filters in or out. (see Annex 1, Fig. 3) c) The recesses promote self-cleaning of the threads. Dirt particles located in the thread are moved by the rotational movement when screwing and fall outwards through the recesses, which are interrupted by the thread. d) The recesses make it easier to grip the screwed-on filters by hand without the use of tools. The narrow filter, which is normally difficult to grasp, can be partially enclosed (the fingernail presses into the recess) and thus rotated with greater force and without the use of aids, providing a better grip. 2. The front thread located on photographic lenses and intended for receiving filters includes the recesses according to the invention, which replaces the use of the adapter in this function.

[0002] The functional characteristics of the adapter according to the invention mentioned under points 1a, b, c and d, and / or the constructive modification of the filter thread on the lens mentioned under point 2, result in minimizing the risk that filters and / or filter adapters screwed onto the lens will be stuck and cannot be moved, or can only be moved with difficulty or with aids.

Claims

[1] Filter adapter for screwing onto a photographic lens, which has recesses (interruptions in the thread) on one or both of its threads. These allow a) the adapter from the lens or b) the filter screwed onto the adapter can be easily and smoothly unscrewed. (see Appendix 1, Fig. 2 and Fig. 3). [2] Lens whose front internal thread, intended for the reception of photographic filters, has the recesses (interruptions of the thread) according to the invention.

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