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tamron adaptall-2 sp 90mm won't focus to infinity?
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PostPosted: Thu Jun 20, 2019 4:27 am    Post subject: tamron adaptall-2 sp 90mm won't focus to infinity? Reply with quote
folks,

i have just come upon a tamron adaptall-2 sp 90mm f/2.5 macro 52b in what seems to me to be nice, unmolested condition.. however, in attempting to use it, adapted to my a7ii, i find that i can not focus to infinity - in fact, i can't focus much more than 5' or so.

the lens came with an adaptall-2 mount for pentax k/a, which i am then adapting to e-mount with the appropriate pk-to-nex adapter.. are there known issues with this configuration? do i need a shorter adapter?


PostPosted: Thu Jun 20, 2019 4:31 am    Post subject: Reply with quote
i've also just now discovered that direct adaptall-to-nex adapters exist, and have ordered one, so perhaps that will address the issue.


PostPosted: Thu Jun 20, 2019 5:40 am    Post subject: Reply with quote
You don't, by any chance, have an extension ring between the lens and the PK adaptor? One of the 90mm Tamrons was supplied with an Adaptall extension tube (or maybe it was an option), that might give the symptoms you describe Wink Alternatively, there's not a close-up lens on the front?


PostPosted: Thu Jun 20, 2019 6:27 am    Post subject: Reply with quote
kypfer wrote:
You don't, by any chance, have an extension ring between the lens and the PK adaptor? One of the 90mm Tamrons was supplied with an Adaptall extension tube (or maybe it was an option), that might give the symptoms you describe Wink Alternatively, there's not a close-up lens on the front?


just checked for both just to be sure, but nope.. i suspect my PK adapter may be having a bad interaction with the adaptall K/A mount, just enough so to bollocks the infinity focus which is apparently extremely short on this lens - the all-in-one adapter on order appears (to my eye) to be at least a millimeter shorter at the shoulder than these two adapters put together, knock wood that solves the problem.. adapter should arrive in a few days, we shall see.


PostPosted: Thu Jun 20, 2019 9:50 am    Post subject: Reply with quote
It looks like the KA mount is not for the K series but for the A series Pentax.

https://www.mosphotos.com/PentaxLensesExplained.html

Could that mean you have the wrong adapter.

I haven't studies the details on the above link.


PostPosted: Thu Jun 20, 2019 11:12 am    Post subject: Reply with quote
From https://www.mosphotos.com/PentaxLensesExplained.html

Quote:
A, F, FA and D FA lenses work on all Pentax bayonet cameras ever produced. Exceptions: 1) A lenses do not work on the MZ-60/ZX-60, 2) the D FA 100mm F2.8 WR and newer D FA lenses have no aperture ring which restricts their use on some film cameras.


and 1mm extension isn't enough to make that lens focus that close only.

My guess is lens has issue. How do those images made closer than 5 feet look? If okay, then likely helical might need restarting. Otherwise an element may have dislodged or be flipped.

Please let us know how new adapter works! Smile


PostPosted: Thu Jun 20, 2019 11:59 am    Post subject: Reply with quote
When focusing to infinity the front end should retract and end up completely flush with the focus barrel. is this the case?

And does the lens seem to perform correctly optically?


PostPosted: Thu Jun 20, 2019 3:25 pm    Post subject: Reply with quote
benadamx wrote:
i suspect my PK adapter may be having a bad interaction with the adaptall K/A mount, just enough so to bollocks the infinity focus which is apparently extremely short on this lens - the all-in-one adapter on order appears (to my eye) to be at least a millimeter shorter at the shoulder than these two adapters put together, knock wood that solves the problem.. adapter should arrive in a few days, we shall see.


I regularly use my 90mm Tamron Adaptall-2 fitted with the PK/A adaptor on my Pentax DSLR's with no problem. Have you tried any other PK-fit lenses on your a7ii with the adaptor?

5ft maximum focus distance seems like a ridiculously close distance for a badly made adaptor. I had a PK adaptor for my Samsung which would only focus out to about 40ft, that was about 1mm too big, to come into 5ft maximum focus distance I need about an 8-10mm tube with the Tamron 90mm set to infinity.

Unfortunately it really does sound like there's something wrong with your lens Sad


PostPosted: Thu Jun 20, 2019 3:38 pm    Post subject: Reply with quote
e6filmuser wrote:
It looks like the KA mount is not for the K series but for the A series Pentax.

https://www.mosphotos.com/PentaxLensesExplained.html

Could that mean you have the wrong adapter.

I haven't studies the details on the above link.


The Tamron PK/A is perfectly backward compatible with the PK mount, the only practical difference is the addition of a set of electrical contacts so a suitably equipped Pentax camera can "read" the aperture information from the lens and display appropriate exposure information. When used in conjunction with any third-party adaptor for use with a non-Pentax camera these contacts are redundant.

Indeed, if the OP so wished, he might profit from selling the desirable PK/A Adaptall-2 mount and replacing it with a much cheaper P/K mount, or indeed the third-party Tamron-NEX adaptor he has on order Wink


PostPosted: Thu Jun 20, 2019 5:19 pm    Post subject: Reply with quote
marcusBMG wrote:
When focusing to infinity the front end should retract and end up completely flush with the focus barrel. is this the case?

And does the lens seem to perform correctly optically?


yeah these details both seem to be fine otherwise, took some very nice close-up portrait and macro shots with it, guess i may yet need to open it up and see what's going on with the helicoid


PostPosted: Thu Jun 20, 2019 5:21 pm    Post subject: Reply with quote
kypfer wrote:

I regularly use my 90mm Tamron Adaptall-2 fitted with the PK/A adaptor on my Pentax DSLR's with no problem. Have you tried any other PK-fit lenses on your a7ii with the adaptor?


i have a few other PK lenses that have been fine with the PK adapter, makes me think something is weird with the K/A adaptall-2 adapter, but indeed it may well be the lens itself, will find out tomorrow


PostPosted: Thu Jun 20, 2019 9:39 pm    Post subject: Reply with quote
Post some pictures of the lens.


PostPosted: Thu Jun 20, 2019 10:39 pm    Post subject: Reply with quote
The helical movement to go from infinity focus to 5m is very small, maybe 5° rotation. On my 52B it extends the barrel barely a mm from the front. So it doesn't take much to cause this problem, however it is a bit inexplicable. I would actually expect an incorrect reassembly of the helicoid to cause more than this... I haven't had one of these lenses apart but there might be say 4 positions to re-engage the thread ie ~ 90° apart which if it causes a loss of infinity focus would be relative to this displacement.
The focus on this lens is not simple extension of the lens away from the camera, the rear group is fixed. A small discrepancy in a mount or adapters is likely to be barely noticeable in terms of missing infinity focus - mmm perhaps I should test this, I'll try mine with an M42 mount plus flanged M42 to PK adapter on my pentax tomorrow.
I take it the infinity mark on the distance scale seems to line up correctly?


PostPosted: Fri Jun 21, 2019 5:05 am    Post subject: Reply with quote
here are some photos of the situation, as well as a photo of my wife and son taken with the lens at pretty close to the current focal range limit.. it really does feel like gaining a millimeter or two could make the difference, we shall see













PostPosted: Fri Jun 21, 2019 5:11 am    Post subject: Reply with quote
just for sake of comparison, here's the combo adapter i ordered



PostPosted: Fri Jun 21, 2019 5:16 am    Post subject: Re: tamron adaptall-2 sp 90mm won't focus to infinity? Reply with quote
benadamx wrote:
folks,

i have just come upon a tamron adaptall-2 sp 90mm f/2.5 macro 52b in what seems to me to be nice, unmolested condition.. however, in attempting to use it, adapted to my a7ii, i find that i can not focus to infinity - in fact, i can't focus much more than 5' or so.

the lens came with an adaptall-2 mount for pentax k/a, which i am then adapting to e-mount with the appropriate pk-to-nex adapter.. are there known issues with this configuration? do i need a shorter adapter?


Hmm, let's my try it on mine some day. I do notice for my Vivitar 35mm f/1.9 N/AI mount, I can focus beyond infinity. Or I should say, when an object at infinite distance is in focus, the actual focusing distance on the lens doesn't reach infinity yet. Haven't figured out why.


PostPosted: Fri Jun 21, 2019 5:19 am    Post subject: Reply with quote
folks, i am an idiot! it's not a KA adapter, it's a Konica-AR adapter! i switched adapters and it works fine now!!



PostPosted: Fri Jun 21, 2019 10:48 am    Post subject: Reply with quote
Laugh 1

How's the throw from 5 FEET to infinity? Smile


PostPosted: Fri Jun 21, 2019 12:11 pm    Post subject: Reply with quote
I was going to ask how did the konica mount connect to the PK adapter, but I have just tried a konica TX mount I acquired with a vivitar 400mm with a PK-NX (samsung) adapter. It does engage pretty well.
So that explains it. I was looking at your pics and noticed the K/R on the mount and I was thinking "hang on..." The adaptall K/R mount is nothing like a PKA, its a lot thicker and doesn't have contacts. And that's your loss I'm afraid the konica mount is near worthless..


PostPosted: Fri Jun 21, 2019 1:05 pm    Post subject: Reply with quote
benadamx wrote:
folks, i am an idiot! it's not a KA adapter, it's a Konica-AR adapter! i switched adapters and it works fine now!!


That would have fooled me! I'd have assumed it was a "K-Ricoh" adaptor, not a "Konica-R" ... would have been running around in circles just like you!

I've just tried a Konica lens on my Pentax DSLR and it simply doesn't fit to any degree, but trying the lens in a PK-NX adaptor does work to a point, so, as I think we're probably aware, a lot of the available adaptors are not manufactured to particularly tight tolerances Wink

Just a note about the Tamron 52B I remembered when i was using mine this morning ... if you fit a rubber lens hood, it may well foul the lens body and prevent infinity focus. I've "extended" the thread on mine with a glassless filter ring so the rubber is held clear of the lens body at infinity. This is probably less of a problem with a rigid lens hood.

Enjoy ... it's a great lens Smile


PostPosted: Fri Jun 21, 2019 1:38 pm    Post subject: Reply with quote
marcusBMG wrote:
I was going to ask how did the konica mount connect to the PK adapter, but I have just tried a konica TX mount I acquired with a vivitar 400mm with a PK-NX (samsung) adapter. It does engage pretty well.

If you are out of the OM lens caps, take one for PK mount.
It fits perfectly.

(however OM lens won't lock on PK adapter, I've already tried that)


PostPosted: Fri Jun 21, 2019 1:59 pm    Post subject: Reply with quote
OM, PK, CY are all very similar in bayonet dimensions, that's why the "multimount" that you can get for a pentax dslr works. An old style nikon F (no protruding "AI" connections) can usually actually be squeezed onto a pentax camera (usually upsidedown). I've also been using my PK-NX adapter with an OM mount lens.


PostPosted: Fri Jun 21, 2019 8:59 pm    Post subject: Reply with quote
benadamx wrote:
folks, i am an idiot! it's not a KA adapter, it's a Konica-AR adapter! i switched adapters and it works fine now!!

Glad it's sorted.
The line for the focus distance being so far off center should have given a clue, but I was too busy looking for the matched 1:1 adapter to notice that.
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