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T4 and TX mounts compared
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PostPosted: Sat Aug 23, 2008 6:20 pm    Post subject: T4 and TX mounts compared Reply with quote

[These are 500pix wide - for large and very large, I include links to the corresponding flickr page.]

T4 and TX mounts compared. These are the naked lens rears, the TX is in the middle, and it's a 28mm vs. the two teles so it has the lens element sticking out.

Each has the same tab - you push the little metal tab in and turn the collar in the O direction to release the mount. Re-attaching it, the collar is ratcheted and locks in place.

The TX has additional linkages available via the mount to permit open aperture metering. Note the little ears where the white arrow is pointing to the left on each lens - this is the aperture ring sensor and it lines up with the arrow when the lens is set to f/5.6. Which is why that aperture is in a different color - you set it there to attach a mount.


http://www.flickr.com/photos/nesster/2790256080/

These are the mounted lens rears, the TX is on the right, mounted on a T4 200mm lens.

Each has the same tab - you push the little metal tab in and turn the collar in the O direction to release the mount. Re-attaching it, the collar is ratcheted and locks in place.

On the web, it is said that you can mount a TX on a T4 lens, but rarely the other way around. Well, I managed to mount the TX on the 200mm T4, however I only got f/4 instead of f/3.5. So it can be done, with limitations.

The PX = pentax screw mount is a bit frustrating, it has a knurled knob that does NOT lock into place for manual operation (ie. on a K mount converter). I can still use it on the screw mount bodies though.

The CS mount in the middle is a mystery - what does CS stand for? It has a big push pin (you can see it at 5 o'clock) that closes the aperture. I'm using a hair bungee to hold it closed when I use this mount on the K100D. Otherwise it is just a M42.

The P/ES is a TX mount, a perfect reproduction of the SMC Takumar mount.


http://www.flickr.com/photos/nesster/2789407083

The rear of the mounts, unmounted.


http://www.flickr.com/photos/nesster/2790255354

The front of the mounts, ie. where the lens goes. You can tell the TX because it is the one that says TX on it. You line up the white arrow to the same on the lens, then tighten the ratcheted collar.


http://www.flickr.com/photos/nesster/2789406319


PostPosted: Sat Aug 23, 2008 7:25 pm    Post subject: Reply with quote

Thank you to showing these , they are vital information for us.


PostPosted: Sun Aug 24, 2008 12:57 am    Post subject: Reply with quote

Very well done !

I'm also drawing a blank on the "CS" mount.

As for that annoying wheel on the screw mounts, I disable that by opening the T4 and removing the linkage. It turns the lens into manual aperture, much better for DSLR.


PostPosted: Thu Jan 29, 2009 9:00 am    Post subject: Reply with quote

Some very useful info on the lens I'm looking at right now. We need more correct information on these as there is so much misinformation floating around. For instance...what serial number starts the TX line and ends the T4 line? When you look on auction sites, you see the release mechanism but the photos do not tell you which is a T4 and which is a TX. I constantly have to ask the seller to open the mount up and tell me if there is a TX in white letters there.


PostPosted: Tue Aug 27, 2019 2:25 pm    Post subject: Reply with quote

Resurrecting this thread in order to include a link to a thread discussing how to mod the T4 lens mount to work with a Pentax PK TX mount.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/311306-converting-t4-lenses-tx-k-mount-adapter.html