Converting T4 lenses for TX K-mount adapter

HHovaness · 01-07-2016, 01:12 PM - **3 Likes**

There is much confusion surrounding the Vivitar and Soligor T4 and TX mount system. Because the only K-mount adapters made were for TX lenses, many K-mount camera owners have used M42 adapters to use T4 lenses with M42 mounts. This means losing auto diaphragm and meter coupling. I did some tinkering with my T4 lenses and a TX K-mount adapter and succeeded in modifying the lenses to function with the TX K-mount adapter. The modification requires cutting away a small portion of the backplate of the T4 lens to allow the TX adapter pin a wider range of movement. This does not impair the appearance or normal operation of the T4 lens. See the attached images for before and after views of a modified lens. The backplate is secured by three small screws and can be easily removed so that the cutting work does not harm the lens. I used a small jeweler's saw, but a Dremel tool would work too. The metal is soft aluminum and cuts easily. Remember to remove the small diaphram linkage pin from the backplate before cutting, so that it does not get lost. Reattaching the backplate is a bit tricky because the diaphram linkage must be properly engaged, but with patience and a few tries you will succeed in making your Vivitar or Soligor T4 lens usable with a K-mount adapter, providing full aperture viewing and metering.

Attached Images

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**marcusBMG** · 01-07-2016, 01:47 PM

Excellent! Well done and thanks.

Would be worth knowing if this works for other TX mounts too...

HHovaness · 01-07-2016, 02:33 PM

I am buying a Nikon AI mount on eBay, so I will be able to test it with the modification. I'll post the results here.

**UncleVanya** · 01-07-2016, 02:55 PM

How do you cut it without spraying metal particles everywhere?

HHovaness · 01-07-2016, 03:24 PM

Originally posted by UncleVanya

How do you cut it without spraying metal particles everywhere?

The backplate is taken off the lens by removing the three screws. After removing the linkage pin, I put the backplate in a hobby vise and cut away the required portion. The aluminum particles produced by the sawing were brushed and blown off the backplate, then it was replaced in the lens (with the linkage pin put back). I was too lazy to photograph all of the steps.

**UncleVanya** · 01-07-2016, 03:33 PM

Originally posted by HHovaness

The backplate is taken off the lens by removing the three screws. After removing the linkage pin, I put the backplate in a hobby vise and cut away the required portion. The aluminum particles produced by the sawing were brushed and blown off the backplate, then it was replaced in the lens (with the linkage pin put back). I was too lazy to photograph all of the steps.

Well that makes sense! You even mentioned removing the backplate but I somehow glossed over it in my mind. Thanks for the explanation.

HHovaness · 01-11-2016, 03:28 PM

I tested the T4 lens mod successfully with a Nikon AI TX adapter. It works, with the exception of the smallest aperture, F22. It will probably work with the other TX adapters too.

Martinhind · 03-20-2019, 04:09 AM

There are still lenses to be found in charity shops out there. Came across two today so hope to use the fix described above for a Vivitar (Tokina 37xxx...) TX 28mm, f2.5, Auto Wide-Angle which I am looking to buy. Selling for £30 which may be on the edge of being expensive.

Read more at: Vivitar (Tokina 37xxx...) TX 28mm, f2.5, Auto Wide-Angle Lens Reviews - Vivitar Lenses - Pentax Lens Review Database

kypfer · 03-20-2019, 04:16 PM

Excellent ... thank you

I don't have any T4 lenses (yet) but I have managed to source a sensibly-priced PK-TX adaptor which I use on my small selection of Vivitar TX (Tokina) primes.

It's good to know I'll be able to use a T4 lens if ever I come across one

Martinhind · 03-21-2019, 11:05 AM

Decided not to buy these lenses as have been spending too much on lenses and cameras and not enough getting out there using them. Will keep an eye on the website maybe make an offer in a few months time to get them cheaper. One of the Vivitars was a 100-300 close focusing zoom and I know that other Vivitar close focusing zooms get a good price but not heard much about this one.

**marcusBMG** · 02-23-2021, 06:29 AM

I just did this to a vivitar 250mm (see vivitar thread).
While I was cutting the plate with my dremel, something small dropped off onto the floor. Luckily I was able to find it - a small screw, one of two holding on the aperture lever. Both had worked loose. something to be careful of.
All working ok now.

kypfer · 06-28-2022, 09:55 AM

Originally posted by kypfer

Excellent ... thank you

I don't have any T4 lenses (yet) but I have managed to source a sensibly-priced PK-TX adaptor which I use on my small selection of Vivitar TX (Tokina) primes.
It's good to know I'll be able to use a T4 lens if ever I come across one

Well … I've "found" a Soligor 105mm f/2.8 in T4 mount so I'll be putting the above modification to good use … Thanks again

01-07-2016, 01:47 PM	#2
marcusBMG Site Supporter Join Date: Nov 2012 Location: North Wales Photos: Gallery \| Albums Posts: 2,869	Excellent! Well done and thanks. Would be worth knowing if this works for other TX mounts too... Last edited by marcusBMG; 01-07-2016 at 01:52 PM.

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01-07-2016, 02:33 PM	#3
HHovaness Inactive Account Join Date: Aug 2010 Location: New York Photos: Gallery Posts: 5 Original Poster	I am buying a Nikon AI mount on eBay, so I will be able to test it with the modification. I'll post the results here.

01-07-2016, 02:55 PM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,445	How do you cut it without spraying metal particles everywhere?

01-07-2016, 03:24 PM	#5
HHovaness Inactive Account Join Date: Aug 2010 Location: New York Photos: Gallery Posts: 5 Original Poster	Originally posted by UncleVanya How do you cut it without spraying metal particles everywhere? The backplate is taken off the lens by removing the three screws. After removing the linkage pin, I put the backplate in a hobby vise and cut away the required portion. The aluminum particles produced by the sawing were brushed and blown off the backplate, then it was replaced in the lens (with the linkage pin put back). I was too lazy to photograph all of the steps.

01-07-2016, 03:33 PM	#6
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,445	Originally posted by HHovaness The backplate is taken off the lens by removing the three screws. After removing the linkage pin, I put the backplate in a hobby vise and cut away the required portion. The aluminum particles produced by the sawing were brushed and blown off the backplate, then it was replaced in the lens (with the linkage pin put back). I was too lazy to photograph all of the steps. Well that makes sense! You even mentioned removing the backplate but I somehow glossed over it in my mind. Thanks for the explanation.

01-11-2016, 03:28 PM	#7
HHovaness Inactive Account Join Date: Aug 2010 Location: New York Photos: Gallery Posts: 5 Original Poster	I tested the T4 lens mod successfully with a Nikon AI TX adapter. It works, with the exception of the smallest aperture, F22. It will probably work with the other TX adapters too.

03-20-2019, 04:09 AM	#8
Martinhind Guest	There are still lenses to be found in charity shops out there. Came across two today so hope to use the fix described above for a Vivitar (Tokina 37xxx...) TX 28mm, f2.5, Auto Wide-Angle which I am looking to buy. Selling for £30 which may be on the edge of being expensive. Read more at: Vivitar (Tokina 37xxx...) TX 28mm, f2.5, Auto Wide-Angle Lens Reviews - Vivitar Lenses - Pentax Lens Review Database

03-20-2019, 04:16 PM	#9
kypfer Pentaxian Join Date: Jan 2018 Location: Jersey C.I. Posts: 3,595	Excellent ... thank you I don't have any T4 lenses (yet) but I have managed to source a sensibly-priced PK-TX adaptor which I use on my small selection of Vivitar TX (Tokina) primes. It's good to know I'll be able to use a T4 lens if ever I come across one

03-21-2019, 11:05 AM	#10
Martinhind Guest	Decided not to buy these lenses as have been spending too much on lenses and cameras and not enough getting out there using them. Will keep an eye on the website maybe make an offer in a few months time to get them cheaper. One of the Vivitars was a 100-300 close focusing zoom and I know that other Vivitar close focusing zooms get a good price but not heard much about this one.

02-23-2021, 06:29 AM	#11
marcusBMG Site Supporter Join Date: Nov 2012 Location: North Wales Photos: Gallery \| Albums Posts: 2,869	I just did this to a vivitar 250mm (see vivitar thread). While I was cutting the plate with my dremel, something small dropped off onto the floor. Luckily I was able to find it - a small screw, one of two holding on the aperture lever. Both had worked loose. something to be careful of. All working ok now.

06-28-2022, 09:55 AM	#12
kypfer Pentaxian Join Date: Jan 2018 Location: Jersey C.I. Posts: 3,595	Originally posted by kypfer Excellent ... thank you I don't have any T4 lenses (yet) but I have managed to source a sensibly-priced PK-TX adaptor which I use on my small selection of Vivitar TX (Tokina) primes. It's good to know I'll be able to use a T4 lens if ever I come across one Well … I've "found" a Soligor 105mm f/2.8 in T4 mount so I'll be putting the above modification to good use … Thanks again