[Squier]

I picked up a junk shop lens recently, and it has a TX mount adapter, and it came with another adapter attached, although they appear not to be compatible, as the threads were different

Here are pics of the TX mount front and back, and note it says P/ES - i dont know that mount, but stangely it fits exactly on my M42 / K adapter. Why is it called P/ES when its M42 ?







The other weird bit - this adapter pictured below was screwed on the TX /P/ES mount. It has 3 threads in total. 2 internal and 1 external. Although it was attached when i got it, its certainly not the right internal thread to be mounted on the TX/P/ES mount. As stated , the TX has an M42 thread for lenses, so this weird adapter does not screw all the way. on . The thread is finer than the M42. And then 2nd internal thread is even finer.







Then the external thread is another m42, and courser than both the internal threads.

Rather confusing to find this incompatible adapter on the end of a TX/P/ES mount.

Anyone know whats going ???

[Lowell Goudge]

looks like you have a T mount to M42 adaptor, If I recvall correctly a T mount has a different (finer) thread pitch than the M42 thread, but is 42 mm diameter.

the other adaptor looks like some form of vivitar interchangeable mount for a pentax ES screw mount, as it has the aperature activation pin and the aperature setting link (last generation of M42 for pentax) which fed the aperature selected into the body. THis gave open aperature TTL metering capability to the ES.

[Squier]

Thanks Lowell - well thats cleared up the weird adapter. T mount to M42 eh ?

And the TX mount - still not sure why its labelled P/ES. I just attached it perfectly to my genuine Pentax m42 - K mount. The TX mount ( mounted on the Viv lens ) also locks nicely into place on the M42 adapter when the adpater is mounted on my K10

[heliphoto]

ES most likely refers to the Electro-Spotmatic or ES.

[Squier]

Thanks - wondered what that was. So that spotmatic must have an M42 thread mount ?

[Lowell Goudge]

Thanks - wondered what that was. So that spotmatic must have an M42 thread mount ?

all pentax cameras before the origonal film K series had screw mounts.

Screw mounts evolved quite a bit.

the initial lenses were manual stop down lenses, where you focused wide open, and metered and shot in stopped down mode, by changing the aperture,

then came automatic aperture with the button to activate stop down. there was a manual auto switch on these so you could switch to manual to meter.

then came the spotmatic ES, which had the aperture coupling, and a second little pin to insure allignment to the body so the coupling gave correct info. this allowed wide open metering as I said earlier.

M42 really only refers to the thread of the mount and the register distance. (i.e. mount to focal plane distance)

[Nesster]

Think of it this way:

The TX 'ES' mount - and the Adaptall-2 "ES" mount ==== SMC Takumar
All other TX/T4 M42 mounts and all Adaptall-2 M42 mounts ===== Super Takumar

(you may get the mounts described as pentax, fuji, M42, etc etc. They all are M42)

I'd love that mount as I only have one...

[Squier]

Well if i can find a TX to K mount adpater, i'll sell the TX to M42

The other thing that thats a little strange, is that T mount adapter pictured with 3 threads. What would the 3rd thread be for ? We can see the M42 external thread, then there's a finer thread inside, plus yet another even finer thread inside next to it ?

[Nesster]

LOL I discover I lie: actually I have a NIB TX P-ES adapter, but lack a second lens to put in it

I haven't seen a TX K adapter, have been sporadically looking. The best chance is most likely finding a TX Vivitar lens with the K adapter on it... I've trained myself to look for the telltale bump and the aperture numbers going in two directions.

[wildlifephotog]

Squier,

The area where the arrow is pointing are not threads. They are ridges to break up reflections from the metal.

[Squier]

Thanks !

I would never have guessed that.

There's also 3 tiny screws around the circumference of the outer knurled ring, so i guessed it could be seperated into two - but why - an adapter within an adapter ?

[wildlifephotog]

The 3 screws are used to adjust the position of the M42 lens. That way if the threads on the adapter are a hair off, you can make sure the lens is oriented correctly, by turning the inner threaded part.

[Squier]

Thanks again - great info