T-mount
Encyclopedia
T-mount is a standard lens mount
for camera
s 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. Thus 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 a solely mechanical specification. Electrical or mechanical connections (such as for autofocus
) are generally not provided, however Sigma's
YS Mount featured an automatic diaphragm coupling.
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.
.
An 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. Thus the external ring of T2-Ring can be directly attached.
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.
Lens mount
A lens mount is an interface — mechanical and often also electrical — between a photographic camera body and a lens. It is confined to cameras where the body allows interchangeable lenses, most usually the single lens reflex type or any movie camera of 16 mm or higher gauge...
for camera
Camera
A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...
s 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
Flange focal distance
For an interchangeable lens camera, the flange focal distance of a lens mount system is the distance from the mounting flange to the...
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
M42 lens mount
The M42 lens mount is a screw thread mounting standard for attaching lenses to 35 mm cameras, primarily single-lens reflex models. It is more accurately known as the M42 × 1 mm standard, which means that it is a metric screw thread of 42 mm diameter and 1 mm thread pitch...
which is also 42mm, but has a 1mm thread pitch.)
The "T" is said to stand for Tamron
Tamron
is a Japanese company manufacturing photographic lenses, optical components and commercial/industrial-use optics. Tamron Headquarters is located in Saitama City in the Saitama Prefecture of Japan....
, 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. Thus 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 a solely mechanical specification. Electrical or mechanical connections (such as for autofocus
Autofocus
An autofocus optical system uses a sensor, a control system and a motor to focus fully automatic or on a manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication...
) are generally not provided, however Sigma's
Sigma Corporation
is a Japanese company founded in 1961, manufacturing cameras, lenses, flashes and other photographic accessories. All Sigma products are produced in the company's own Aizu factory in Bandai, Fukushima, Japan...
YS Mount featured an automatic diaphragm coupling.
Besides cameras, applications include optical breadboard prototyping components, and telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
and microscope
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
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.
Adapters
Because the T-mount has a long flange distance of 55mm and most 35mm cameras have shorter flange distances, 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 focusInfinity focus
In optics and photography, infinity focus is the state where a lens or other optical system forms an image of an object an infinite distance away. This corresponds to the point of focus for parallel rays. The image is formed at the focal point of the lens....
.
An adapter ring has a female M42x0.75 metric thread on one side and a corresponding lens mount
Lens mount
A lens mount is an interface — mechanical and often also electrical — between a photographic camera body and a lens. It is confined to cameras where the body allows interchangeable lenses, most usually the single lens reflex type or any movie camera of 16 mm or higher gauge...
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. Thus the external ring of T2-Ring can be directly attached.
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.
External links
- T-mounts, Aperture, and Vignetting. Finger Lakes Instrumentation.
- Making Digital Camera Microscope Adapters. Various examples and machining details of custom-made T-mount adapters.