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T-mounts T, T-2, T-4, TX ???

Brian Carter

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Second in a series. I know the T-mount designations are chronological, but

what are the differences? Which are interchangable with which? T and T2 are

the same? T4 and TX are improvements, or just different uses? Just point me to

the website that has the distinctions all laid out nice and simple...

Thanks/Brian (Please see my similar question re: Vivitar tele-converters.)

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T and T2 are basically the same. These are mounts for "pre-set" lenses, telescopes, etc. They are 42mm diamater, same as Pentax/Practica lenses, but different pitch. T4 was for automatic diaphragm lenses, TX came later when some camera makers introduced shutter-priority autoexposure, TX and T4 are not always interchangeable, I don't know all the details. Hope this helps.

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  • 1 month later...

The original T-mount came out in the mid to late 50s when Tamron (then known as Taisei ) designed and manufactured them. The T-2 is identical to the original T mount except it has screws which allow the lens and camera body to be realigned in case it is "off". The T3 mount wasn't widely known but it is more commonly known as YS mounts Sigma/Sun lenses made these during the 70s. They are basically T/T2 mount lenses with some degree of lens automation. T/T2 and T3/YS lenses are interchangeable but a T/T2 mount on a T3/YS mount lens loses the T3/YS automatic diaphragm capabilities. The T/T2 mount had no automatic linkage whatsoever with the host lens. The most they could develop was a preset aperture which had to opened to view the subject through the slr then stopped down to shooting aperture to take the shot. Not that great for fast shooting unless the maximum aperture also happened to be the shooting aperture. (Okay for sports/wildlife shooting).


The T4/TX mount is a later development. Both Soligor and Vivitar had lines

of The T4 lens mount during the late 70s and 80s. They are a bayonet type of mount so they are completely incompatible with the screw thread attached T/T2/T3/YS mounts. The T4 mount lens lines evolved into the TX line (at least at Vivitar). Generally speaking TX mounts had a higher degree of automation then the T4 mounts. Again generally speaking T4 mounts can be used on used on TX lenses more successfully then TX mounts on T4 lenses with the corresponding loss of automation necessary to achieve backwards compatibility. The main difference between the T/T2/T3 system and the T4/TX system was that there is a high degree of automatic aperture linkage between the lens and mount. I believe the T4 had stop down meterig capability while the TX was full open aperture metering enabled. It could also have varied from camera mount to mount on the degree of automation (for example some camera companies at this time only had aperture priority and manual exposure capability in their cameras (Nikon Pentax Olympus) while others were shutter priority and manual (Konica Canon).


In general T/T2 mount lenses are still made today as the primary lens mount for mounting still cameras on telescopes as well as mirror lenses and some preset/manual diaphragm super telephotos (the old school generic 400mm f/6.3 and 500 mm f/8.0 preset long lenses and newer school super zooms like the Praktica/Cosina 650-1300 mm are good examples).


If buying an older T mount lens whether it's T/T2/T3/YS/T4 or TX just remember a few rules of thumb. These were made at a time when zooms with a few rare exceptions (Nikkor 80-200 F/4.5 amd Vivitar Series One 70-210mm F/3.5) were markedly inferior to prime/single focal length lenses. Stick with simple primes like 28mm/35mm f/2.5/2.8

100mm/105mm/135mm f/2./2.8 and you'll probably get solid optical quality for cheap.


This is an older question but I hope this info helped some.

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