Using Vintage T-mount Preset Lenses
About t-mount
"The T-mount is a standard lens mount for cameras and other optical assemblies. The usual T-mount is a screw mount using a male 42x0.75 (42 mm diameter, 0.75 mm thread pitch) metric thread on the lens with a flange focal distance of 55 mm and a mating female 42mm 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 [aka pentax thread, pentax universal] lens mount which is also 42 mm diameter, but has a 1 mm thread pitch.)
The "T" is said to stand for Tamron or Taisei, a Japanese manufacturer that released in 1957 the first of a line
of aftermarket camera lenses that fit 35 mm SLR cameras built by various manufacturers using their universal T-mount.
On the first model, the mini T-mount used a M37x0.75 thread; Tamron's canonical M42x0.75 T-thread didn't appear on the
market until about 1962. The company referred to it variously as a T-mount, T-thread, T-adapter, or a T-400, but not as
a T-2,which is simply the name that Soligor used for its version of the T-adapter.
The proprietary lens mount of each camera manufacturer was adapted to the T-mount thread with a simple adapter."
- Wikipedia.
So strictly speaking the t-mount is the connection on the lens but if you browse eBay for example you will find that everyone refers to the adapter that connects to the camera as a t-mount, even though it should strictly be called the t-ring. Here I follow that so when I say t-mount I usually mean the connection to your camera.
Difference between T-mounts, T2-mounts, T4 and TX mounts?
All the T and T2 mounts I've seen have been the same. There is no distinction that I have observed between T-mounts and T2-mounts - the change in nomenclature seeems to have been just marketing.
T4 and TX mounts however are completely different and completely incompatible with T/T2.
These Tokina made swappable mounts are illustrated
here (bottom of the page),
were marketed by Vivitar and Soligor to provide auto aperture linkages that t-mounts didn't, and are only found on their lenses.
There also exists a variant T4 mount marketed briefly in the USA as the
Lentar Automount, and also by Hanimex.
Preset Aperture
"Preset" refers to lenses with entirely manually operated apertures. Typically preset lenses have two rings (sometimes one dual purpose ring as in the pic left), one to set the desired f-stop, marked with f numbers (the silver ring in pic right), one to open and close the iris often marked O - C (the black ring in pic right). Because this second ring has no clicks, preset lenses have a certain cachet with video shooters, who prefer clickless aperture control.
Since t-mounts have no electrical or aperture lever connections to the iris or the camera, t-mount lenses are all preset lenses.
The T-rings/T-mounts
The strip-pic illustrates some t-mounts. Hover for magnified view.
Pic #1 is the common M42 t-mount, on the end of a Soviet era Jupiter lens.
Pics #2, #3 are of old mounts canon CF and M39; #4, #5 are of Nikon F and pentax K bayonets, these fit on current cameras.
#6 is a new modern clone t-mount from China that will fit Sony "A" mount DSLR's (not "E" mount - Nex). Finally while
almost all of the t-mounts are the normal black anodised finish, #7 is an example of a plated one
(which for some pentax DSLR's makes a difference see below).
All these rings are two piece designs. There is a central collar, C in pic #8,
which can be removed by unscrewing 3 small "grub" screws G
located on the circumference of the ring. The main purpose of this is to be able to align lens and camera (particularly M42's) -
loosening these three screws allows rotation of the ring against the collar. Then there are also some Soviet era lenses (Jupiter, Tair), pic #9,
that use a t-mount style swappable mount, but without the collar. These normally have a -A
designation in the name eg Jupiter 11-A, Tair 300-A.
The end of the lens is machined like the collar.
To swap mounts the collar is removed from the t-mount which is then slotted on the lens and the grub screws tightened.
One detail to note: the interior collar is usually, but not necessarily, interchangeable between mounts. It is typically ~ 48mm in diameter,
but some are not, like the M39 t-mount in the pics. The latter will not fit on the Soviet lenses.
Although M42, as explained above, is 1mm pitch as opposed to 0.75mm pitch
of the t-mount, in practice I have found that, depending on the tightness/machining of the threads, it can be
possible to mix and match. For example I have successfully screwed t-mounts on certain M42 extension tubes - #10 (but to screw an M42
tube onto t-mount you will normally need an adapter like
this one).
T-rings for Nikon and Canon with electrical contacts
The pic illustrates Chinese made t-mounts with contacts. Canon has the flat contacts, Nikon the "dandelion" contacts.
The point of these is that some DSLR's have more restricted functionality, or may even throw an error,
if the lens does not have a microchip to communicate
with the camera. The models that are affected are typically the cheaper consumer range ones,
and the Nikons more than the Canons (more Nikon info here).
Check your manual and online information for the particulars for your camera.
I have also seen t-mounts for Sony "A" mount with contacts.
Mounting a T-mount Lens on your Camera
Thanks to the Chinese manufacturers, t-mounts are available not just for the cameras that were being made at the time (Nikon F, Pentax PK, Minolta MD, Canon CAF, Olympus OM, M42, Miranda, M39, Exacta et al) but for most DSLR's as well. However for most cameras there are two ways to go:
- A new, direct t-mount to camera, adapter (the lens end of these is a female 42mm x 0.75mm thread).
- An original t-mount combined with an adapter from your camera to match that mount.
The advantage of the latter approach is that you are then set up to use both t-mount lenses and also lenses of that mount. So if, for example, you have a bunch of old olympus OM lenses, then the way I suggest to go is to get an adapter for your camera to mount OM lenses, and acquire an OM t-mount to use on your t-mount lenses.
Registration Distances
There is however a complication. Different cameras had a different registration distance for their lenses. The registration distance refers to the distance from the end of the lens (the mount flange) to the film (or sensor in todays cameras). If your digital camera has a larger registration distance than the lenses you would like to mount then there's a technical problem: you will not be able to focus to infinity!
There's no way around this, not without altering/modding the lens (or using an optical adapter). To see if there is a problem consult this list of registration distances. For t-mount lenses here is a summary of what works for the most common cameras:
- Nikon DSLR (and Fuji DSLR with Nikon mount): Nikon's are the least flexible because Nikon has the longest registration distance of DSLR's at 46.5mm, therefore using a readily available Nikon F t-mount is basically the only way to go. There are no complications with Nikon t-mounts, unlike old model Nikon lenses, there are no aperture connections to snarl up. However many of the consumer level models (D40, D60, D70, D5100, D5300...) have rather restricted operation with non-chipped lenses - manual operation only. With these bodies a t-mount with the dandelion electrical contacts, often referred to as an "AF chip", can enhance the cameras functionality, as already mentioned above.
- Canon, Sony (Minolta), Olympus DSLR's: the original t-mounts are for, respectively,
the FD bayonet, the MD bayonet, OM bayonet and don't work because the DSLR mounts are, respectively,
EOS, Sony A, 4/3 (four-thirds). EOS and A mounts were introduced initially on film cameras in the 1980's, but the Olympus 4/3 mount was new for dgital.
New t-mounts are made for these cameras and that's one way to go. The alternative is to use the M42 t-mount with an additional M42 adapter, and for many users this will be the preferred way, due to the easy availability of cheap M42 adapters, some of which have helpful electrical contacts. - Pentax DSLR: Using a specific PK t-mount is the recomended way to go, although it would be perfectly OK too to use an M42 t-mount with a rimless M42 to PK adapter.
- CSC mirrorless - Sony (Nex) E mount, Panasonic/Olympus "micro-four-thirds" (MFT/M43), Pentax "Q", Fuji,
Nikon "1" system, Samsung NX, Canon EOS M and
other interchangeable lens systems: due to
the short registration distances both options are good however
I can suggest that option 2, an original mount + an adapter from your camera to that mount,
is the most versatile approach.
And if you're free to choose any adapter and you want to know which is the most versatile/practical choice I suggest:- M42 adapter. M42 is the most common t-mount, it is the most common mount for vintage lenses pre mid-seventies including classic East Bloc lenses (Helios, Jupiter, Pentacon, Carl Zeiss Jena etc), Asahi Takumars etc. and lots of third party lenses were produced with M42 mounts through the 1970's and into the 1980's. So lots of choice.
- PK adapter. Pentax were the biggest selling cameras of the period so there are more PK mount lenses than others.
- OM (olympus) or MD (minolta) or CY (contax Yashica) or CFD (canon) adapter. Excellent ranges of OEM and third party lenses were made for these obsolete mounts, and because they don't fit modern dslr's (without adaption) prices are advantageous.
Using the Lenses
It is impossible to be detailed about all the different camera models on this page. I will use my Pentax DSLR, Panasonic Lumix G1 and Samsung NX20 mirrorless cameras as examples. The principles will be the same for your camera, the details you will have to figure out for yourself.
As mentioned above, there are no connections between the t-mount and the camera. The first thing, then,
is to check that your camera will operate even though it will not detect that there is a lens attached.
On my pentax I have to dive into the set up menu (last page) and set "use aperture ring" to "2" (=yes).
On my Lumix G1 it's "use without lens" to "on". Until that's done - won't work!
Then set the camera to "MF" - manual focus. Other settings may need tweaking, depending on your camera model.
My Samsung however was more amenable - no menu changes or switch to MF was needed.
The next thing to realise is that all those useful modes Auto, Program, Sv, Tv will not work. The only possible modes are Av (aperture priority) and M (manual). Furthermore, what metering modes can be used and whether focus confirmations/assist modes can be used all needs to be figured out.
Finally changing the aperture is done manually. Set the desired aperture in advance and then quickly stop down with a flick of your finger at the instant of pressing the shutter. Mr Pentacon-Six shows the principle in this u-tube video with a Pentacon lens.
Pentax DSLR
Assuming you have a PK t-mount, no adapter is needed and the lens mounts on the camera in the normal manner. Then using the lens on Pentax is pretty much the same as using a M42 screwmount lens.
Manual Mode M
Manual mode on Pentaxes with lenses without electrical contacts is operated by the "green button" - pressing the green button prompts the camera to stop down to the set aperture, meter and set the shutter speed. This works fine with all normal PK mount lenses, the PK mount has a lever that connects to the aperture and the shiny metal surface of the mount means the camera knows that a lens is mounted. Note that metering is restricted to center-weighted or spot. A good feature of Pentax is that the green light "focus confirm" is still functioning, but only for the subject in the centre of the viewfinder.With t-mounts (and M42 mount lenses) on my Pentax K-r however, the black anodised finish of the lens mount is electrically insulating which changes things. There is now no clunk-click of the camera attempting to move the aperture on pressing the green button. But pressing the green button does prompt the camera to meter and set a shutter speed. Spinning the e-dial then changes the shutter speed so you can tweak the exposure. Another effect of the lack of electrical connection is that catch-in focus (aka trap focus) doesn't work.
Aperture Priority Mode Av
So aperture priority (Av) is really the mode of choice. Typical technique is to focus wide
open, then use the aperture ring to stop down just prior to pressing the shutter.
Av is an automatic mode, metering is continuous so the shutter speed is set "on the fly" by the camera at the moment of pressing the shutter.
And in principle this works well, but for one thing: there is normally some inaccuracy with the metering.
I get around this by "chimping" - take some pics to see what discrepancy there is from good exposure and dial in an appropriate level of
exposure compensation. Once that's done you're usually set to go. However my Pentax K-r is problematical:
I am often maxed out on +3eV, leaving me with no exposure flexibility for the shot.
A way round this is to shoot in Live View - the exposure discrepancy reduces to a more normal amount LV (Why? ask Ricoh Imaging!).
Another way round this is to create an electrical connection at the mount, either by improvisation (bit of foil),
a bit of DIY (removing the black paint),
or by using a plated t-mount as in pic #7 above. For some reason this makes the difference
to the camera and the underexposure reduces typically around 50-70% (and catch-in focus is back too).
This post
on Pentax Forums analyses the K-r's behaviour a bit more.
Update - I have now replaced the K-r with a K5 and the behaviour of that is much more consistent,
with no exposure discrepancy between Live View and viewfinder use.
Regular users of manual focus lenses are recommended to look at aids to focus accuracy: viewfinder magnifiers; viewfinder screens better optimised for visual focus. This is a very useful summary by Pentax Forums contributor Stevebrot.
Panasonic Lumix G1 and Samsung NX20 mirrorless interchangeable lens camera.
Using a variety of lenses is, IME, easier on mirrorless cameras than on standard slr's. Once the lens has been mounted with the appropriate t-mount and adapter, stop-down Av is as above the mode of choice. And at this point the mirrorless cameras have these advantages over the Pentax:
- They still have the choice of metering modes: multiple (matrix), spot, or centre weighted. There are no exposure compensation issues other than might be demanded by the ambient lighting or subject, metering is normal and accurate.
- The Electronic Viewfinder (EVF) automatically compensates for the dimming due to stopping down. In my experience the EVF stays bright all the way down to f11 or so, depending on the ambient light and the lens being used (this is a great visual of depth of field).
- Magnified "focus assist" modes are quickly and easily activated with one (NX20) or two (G1) button presses
which with a bit of practice can be done without removing ones eye from the EVF. Focus then is very accurate.
However it is impractical with moving subjects, or hand-held with longer focal lengths, because the image jumps around too much.
Neither of my mirrorless cameras have a focus confirm feature however. But focus peaking is becoming more prevalent on newer models.
Conclusion
The swappable mount of t-mount lenses makes them versatile, and means they can be
readily mounted on all DSLR's and mirrorless CSC cameras. In fact it is for that reason that some
t-mount lenses are still being manufactured. Although their operation on modern cameras is limited
in function, their simplicity makes them cheap.
T-mounts are also used in other optical settings like Photomicrography, Digiscoping, Astrophotography, indeed anywhere
where cameras need to be connected to optical instruments.
So what are the cool t-mount lenses? Well TBH they were mostly in the consumer lens category, made in quantity to sell to the range of camera owners. Most popular are probably the long focal lengths: 300mm, 400mm, 500mm, 600mm, both refractive and mirror designs. Although slow and often with rather distant close focus (10m or more), resolution tends to be pretty ok, and at a tiny fraction of the price of modern lenses of that focal length they are a cheap introductory way of acquiring telephoto skills, experience and images. Aficionados also search out particular prime lenses from brands like Soligor that have acquired a reputation for good quality, and Eastern Bloc (USSR) origin -A Jupiter and Tair lenses.
>Sigma YS swappable mount system
Sigma's YS swapable mount system was derived from the t-mount, but included auto aperture connections. Pic
here.
According to Yu-Lin Chan on his lens bubbles blog:
" ..Of all the interchangeable mounts, only the
Tamron Adaptall evolved ... (continuing until autofocus took over).
But, the YS mount did enjoy a brief period of prosperity.... YS mounts were available for all major cameras of the time....
M42 (two versions), Minolta SR and MD, Yashica Contax, Nikon F (there is also an IA version), Konica KR, Pentax K, Leica R ...
The YS adapter derived from the T-mount, but provided auto aperture function, whereas T-Mount lenses invariably have a pre-set
aperture. This allowed lenses to have an open aperture metering. ... Changing the mount is like mounting an M42 lens.
The mount can be unscrewed, and a new mount can be replaced. "
And wikipedia says:
"....Sigma, Upsilon, Accura, Polaris, Sun, Aetna, Beroflex, Petri, Raynox, N.P.S., Formula, Dionar, Universal, Soligor, Yashica, Spiratone.
M42×0.75 (not to be confused with M42×1) Same as T-mount but with aperture coupling."
In sum, this mount may be found on Sigma and 3rd party rebranded Sigma lenses made up to the end of the 1970's.
If you don't have a YS mount of the right type to hand,
a t-mount can be used instead, but aperture will need to be operated manually.
Appendix 1: 47mm thread "t-mount"
The pic shows a standard t-mount to the left and a mount made by Tokina for a while in the ?1960's to the right. Although it is very similar, it uses a 47mm thread not a 42mm thread. After a while this was discontinued in favour of the standard t-mount. However many Tokyo Koki (Tokina) made lenses from the era (and they can be found under a wide variety of names: Palinar, Minetar, Lentar, Hanimex et al) may have this mount. If the lens doesn't come with one the 47mm rings are hard to find. And of course the normal t-rings won't work.
Useful Links/More Info
- Prof Dietz gives a good account of the different varieties of M42 lens and their aperture mechanisms.
- Prof Dietz gives a thorough overview on using old film era lenses on modern dslr's.
- Modifying aperture pin, M42 mount - Pentax Forums
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