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08-07-2009, 12:30 PM   #1
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Vivitar 28mm f/2.5: What's the value of having a TX mount over M42?

I'm looking at two similar versions of the Vivitar 28mm f/2.5 lens: an M42 mount and a TX mount w/ TX-K adapter. I already own and regularly use a M42-K adapter. The price is a little more for the TX, but that doesn't bother me. I'm wondering what value others have found in having a TX adapter.

The way I see it, there's only any value to the TX version if there are other TX lenses that are worthwhile to own. From what I gather, the TX adapter can mount some T4 lenses, too.

I'm just not that well versed in TX lens lore to know if I should be interested, so your thoughts are welcome.

08-07-2009, 12:42 PM   #2
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The TX-PK adapter is fairly rare. I paid $20 for one a few years back (and later sold at the same price to a friend).

It was $50 in a recent sale.

An M42 lens requires an adapter and needs to be closed down manually, which can be cumbersome at times. PK-mount lenses are easier to use.

You may run into other TX lenses later.

The TX adapter, as it is, can be mounted on T4 lenses, but the use is severely limited. You can easily modify the TX adapter to work fully on T4 lenses. I'll dig up some links later for you.

Edited to add:

Here's my post on modifying TX adapter: Modifying TX adapter to work with T4 lens

Last edited by SOldBear; 08-07-2009 at 12:45 PM. Reason: Add link
08-07-2009, 02:01 PM   #3
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TX adapter advantage: - there is a Pentax ES adapter which works with the ES and SPF open aperture metering. There is a Nikon Ai adapter, I believe as well, if that's ever a need. And there's that K adapter, which does provide an easier shooting experience on a K mount camera.


I have 2 Tx 28/2.5's - and still kick myself for not buying that NIB one at the camera show (when my first one still worked). The first copy's focus went bad - but it shows evidence of someone having messed with it, so I don't think it's a general reliability problem.

I like the lens very much, though it's larger than the Pentaxes, it resolves nearly as well and has certain rendering and saturation advantages... in actual picture taking terms, I'd call it even.
08-07-2009, 02:54 PM   #4
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Multi-mount fever

QuoteOriginally posted by indytax Quote
I'm wondering what value others have found in having a TX adapter.

The way I see it, there's only any value to the TX version if there are other TX lenses that are worthwhile to own. From what I gather, the TX adapter can mount some T4 lenses, too.
There's the problem -- you end up with a shoe box full of assorted and unused adapters which just encourages LBA -- PLUS you spend an inordinate amount of time perusing auction sites lookin' for sleeper-lenses with TX/T4/Adaptall mounts at BARGAIN prices.

I've had two M42 Vivitar 28/2.5's and they're nice lenses -- wish I had been that smart about some others -- with no inherent design or IQ differences from their multi-mount siblings.

If you're a gadget-guy, get the TX. If you just wanna take pictures, make it easy an' get the Pentax-mount.

H2

On the other hand, you can spend many rainy afternoons trying to figure out what goes with what in that shoe box.

08-07-2009, 04:41 PM   #5
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I'll echo pacerr. I have shelves filled with T4/TX lenses and a shoebox full of adapters. The older T4 adapters can be used on TX lenses. Using TX adapters on T4 lenses is problematical. I haven't yet tried it, but I think the T4 lenses can be modified for more compatibility with the TX adapters. The value in these is if you have a shelf full of various, old 35mm SLRs that you like to shoot with.

Here's something I wrote about T4 six or seven years ago.
T4 For Two

The traditional Vivitar fixed mount 28/2.5 has a flared front section and was manufactured by Kino. The TX series 28/2.5 is a newer design manufactured by Tokina. It may also be available as a fixed mount Vivitar. It should take a 58mm filter. The Kino versions have serials beginning with 22. The Tokina version would have 37 for the first two digits.
08-07-2009, 05:58 PM   #6
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Full disclosure/ad: I'm selling a 28/2.5 and the 135/2.5 in the marketplace.

The lens itself seemed like a decent performer. I included one in my 28mm test. Swapping the adapters is an inconvenience. There probably was a TX cap that came with the lenses which would make this more convenient. It's easier if you obtain multiple adapters, though more expensive. There are two TX-M42 adapters, one labeled PX and one for the ES that can do open aperture metering. The ES one has a more useful auto-manual switch.

Once you recognize the look of the lenses, you can hunt for bargain lenses without a mount or with something weird that no one wants.

The only other TX lens I've tried is the 135/2.5, which I think is pretty good. See my 135mm test for that one. I have also included a 28mm f2.8 T4 lens in my 28mm test. I have a 300mm f5.5 T4 as well, which I still haven't used for much. I decided not to continue with the system after my tests showed I already had better lenses.
08-07-2009, 07:40 PM   #7
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QuoteQuote:
The TX adapter, as it is, can be mounted on T4 lenses, but the use is severely limited. You can easily modify the TX adapter to work fully on T4 lenses. I'll dig up some links later for you.
hey SOldBear, I just managed to "modify" my T4 lens so that it fits on PK adapter with no restrictions and there's no need to modify the adapter (so it fully works with TX lenses).
The thing is, the "mod" is not undoable - unless you find another donor T4 lens. Here's what I did : there are two forks inside the lens, one is in the "window" with an arrow mark, and another one in an unmarked "window". Both are useless for PK mount. So, take the pliers and break off ONE leg of the fork from the unmarked window - the one that gets blocked by the pin from PK adapter - if you look at the lens so that the "O<->L" is above the rest of the lens, it's the leg to the left of the fork. To break it, you might have to unscrew the three small screws that hold the upper plate - be careful not to lose the aperture pin. Then, hold that left leg with pliers and bend it around a bit - it will come off eventually. After that, put the plate back (with aperture pin in place) - and that's it! PK adapter works wonderfully with it, AND you get widest aperture, AND the aperture ring won't go to the other side.
I'll upload a pic so that it's less confusing.

Bo.
08-07-2009, 07:52 PM   #8
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Ok, here. You can see the fork with a broken foot.
Before this attempt, I tried also gluing something to the inside of the lens so that fork gets blocked at the place I want it to be blocked (that is, at the widest aperture), and the adapter did not have any stuff in it except for aperture stop-down mechanism. That didn't work - the glue wasn't strong enough to block the fork; you still see residue though
The "new" method of breaking that leg works beautifully though

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08-08-2009, 03:18 PM   #9
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Thanks for all the thoughts and links. I'm also gald you guys corrected me on teh T4-TX compatibility confusion I had.

I'm not sure what route I'll take, but I'll be deciding over the weekend. Obviously, I'd prefer a K mount Viv or Pentax 28 for the convenience on my K10D, but right not the prices for those are absurdly high. The TX or M42 would give me the ability to use it on my Yashica TL Electro-X, but that isn't a huge concern. I guess a TX-Ai adapter would allow convenient use with my Nikon FE, too, but I have film K mount bodies, too.

Other than the 135mm TX, I'm not sure I'd have a lot of use for the TX adapter from what I've read. I suppose I could always give it a whirl and sell it later if I'm not pleased!
05-23-2012, 08:31 AM   #10
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Hey guys,

I have just got this lens this morning and it is a TX mount to Nikon. However one problem is that the mount is not AI as there is no connector from the mount to the camera body "prong". I realize that after mounting on camera body, the lever on the mount will push the iris blade wide open even I choose a smaller aperture value. As a result of that, the camera can't meter at correct aperture value, it always meters at f2.5. I can't use the lens in stop-down shooting. I can only shoot in f2.5.

Can I put something to fix the lever on the mount fix without damaging the camera body? (There is another lever that touch the lens mount's lever and press it down) Or is there any way to use in stop down mode?

Thanks
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