Versatility, and saving money with the continued use of the preferred lenses you already own.
lens adapters is the inconvenience, no electronic connection between the adapted lens and your camera body
A couple of factors are necessary for a lens adapter to work properly. First, the camera body "lens registration" space or the expanse between the mount of the lens to
the sensor or film surface. Two, the "throat size" of the mount or the mount diameter. An adapter flanked by the body of the camera and a lens from different brands, this
registration distance of the adapted lens must be larger than the registration distance on the body; plus the lenses throat-size must be less than the throat size on the
Interchangeable mount systems:
Some lenses don't fit directly on any camera without a mount. They are designed so that when the proper mount is attached, they will fit almost any camera.
T-Mount lenses: many pre-set lenses, mirror lenses, slide duplicators and other devices that don't have an automatic diaphragm use a system of interchangeable "T-mounts". Most T-mounts cost about $15-20. There are some female T-mounts available that allow you to do things like mount a Leica (39mm thread) enlarging lens on a bellows for close-up work. Example: the Beseler Dual Mode Slide duplicator uses a T-mount at the top, to mount the camera. It uses a female T-mount at the bottom to mount an enlarging lens, which is an excellent choice for copying or duplicating slides.
T-4 mounts are an interchangeable mount system that allow automatic diaphragm operation. Vivitar and Soligor made them. Mounts and lenses are interchangeable between the two makers.. T-4 lens adapters were not made for Konica or any shutter- priority system -- with the possible exception of Canon (the mount fits, but EE exposure is erratic.) TX is a later system that allows programmed operation and shutter priority. Some TX and T-4 mounts are interchangeable.
Tamron has had three separate systems:
Adapt-a-Matic (adapters for these lenses are no longer available
Adaptall-2 (almost the same is Adaptall)
T-mount is a standard lens mount for cameras and other optical assemblies. The T2 version is a screw mount using a male M42x0.75 metric thread on the lens with a flange focal distance of 55 mm, and a mating female thread on a camera adapter or other optical component. This thread form is referred to as T-thread. (This should not be confused with the M42 lens mount which is also 42mm, but has a 1mm thread pitch.
The "T" is said to stand for Tamron, a Japanese manufacturer, who in 1957 made a line of aftermarket camera lenses all using their T2 T-mount as a universal fit to
35mm SLR cameras of various manufacturers. The proprietary lens mount of each competitive manufacturer was adapted to the T-mount thread with a simple adapter. As a result a retailer could stock a small number of expensive lenses that would fit a large number of camera brands using a selection of inexpensive adapters.
The original T Mount slides onto a T mount lens. It is secured only by 3 set screws that match a channel on the lens mount so that the lens barrel is not deformed by the set screws, and it can therefore be removed with no problem.
The T-mount connection is only a mechanical specification. Electrical or mechanical connections (such as for
autofocus) are not provided.
Besides cameras, applications include optical breadboard prototyping components, and telescope and microscope attachments. As a common mechanical interface, T-mount allows components of various manufacturers to be interchanged and assembled.
The T-mount is the standard way to mount a camera to a microscope to photograph pathological specimen slides.
Because the T-mount has a long flange distance of 55mm and most 35mm cameras has shorter flange distance, a simple mechanical adapter called T/T2-Ring is needed to adapt a T-mount lens to any camera body without optical correction to achieve infinity focus.
A adapter ring has a female M42x0.75 metric thread on one side and a corresponding lens mount of the camera body. The differences between T-Ring and T2-Ring is that a T2-Ring consists of an inner ring with T-mount thread and an external ring with corresponding lens mount. Both rings are held together by 3 peripheral screws on the external ring. Slackening these screws allows rotation between the lens and the camera body. This is especially useful when the camera body is attached to telescopes or microscopes.
The thickness of the external ring is equal to the difference of flange distance between T-mount and corresponding lens mount in order to achieve infinity focus.
Standard T2-Rings have the same external diameter of the inner ring. The reason is that some T-mount lenses have their inner ring built on the flange. As a result the external ring of T2-Ring can be directly attached.
A T-ring converts a camera's mount to a standard T-thread, allowing you to couple a camera body to a camera adapter or, in some cases, directly to the focuser of a telescope. All camera adapters, including Celestron and Meade T-adapters and universal camera adapters, will fit this T-thread. Have a new digital SLR camera?
There are T-rings that fit it.. The #5224 T-ring fits the Canon 300D Digital Rebel, also the 10D, 20D, 20Da, 30D, 350D, and 5D digital SLRs. For Nikon DSLR owners, the #5205 T-ring is compatible with the Nikon D50, D70, D70s, and D200.
Other large format camera lenses have flange distance longer than 55mm. They can be attached to smaller format cameras with a combination of corresponding lens-to-T-mount-adapter and a T2-Ring.
The T Mount is an older lens mount that has a threaded mount measuring 42mm like the Pentax Screw Mount lenses BUT it is not the same. The T Mount is a fine thread and the Pentax a coarse thread. The T Mount was used for a wide variety of items, not just lenses. Some of the other items with this mount are a slide copier, very long telephoto lenses up to 1000mm, spotting scope, binocular adapter, microscope, bellows units, etc. The lenses are considered "aftermarket" and made by many different manufacturers. One thing I would like to point out about these lenses. They were made at a time when everyone shot slides. As you know slide film is not as forgiving as print film. The lenses had to be good or the results were bad and the lenses would not sell. My own experience with these lenses has found them to be quite capable and very sharp. The lenses are plentiful and inexpensive. You will of course loose the auto focus ability, all T Mount lenses are manual focus. You will also loose the auto and program modes, the only way to use it is metered manual and manually stop down the lens for metering and shooting. If you have priced a long telephoto lens lately, 400mm or longer you will see what a terrific bargain this ring and a T Mount lens will be for your camera. I will guess you can get both for less than $100.00. The most common use for them these days is to mount a 500mm or longer Mirror telephoto lens to a Nikon Digital SLR like a D1H, D70, etc. camera. With the cost of new telephoto lenses it pays to buy a nice used T mount lens and this ring. It will fit every Nikon F mount cameras ever made. This of course includes the current digital cameras made today.
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