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12-13-2017, 10:19 PM   #1
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Tair 11A not focussing to infinity in K-1

The Tair 11-A lens (black version) I bought recently gives good results in terms of focusing sharpness up to 6 meters. It gets blurred beyond that, accompanied by lack of focus confirmation by K-1. I am using the Pentax original adapter for M42.

Rather strangely it works well in Sony Mirrorless that a friend of mine has.

Grateful for any advice on how I can make the lens focus to infinity since I like the lens in terms of both sharpness and contrast.


Last edited by Nightsword; 12-13-2017 at 10:21 PM. Reason: To add information on adapter used
12-13-2017, 10:34 PM   #2
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I have the silver version, and it also does not focus to infinity on k-5. I haven't tried to adjust it as I use it as a portrait lens. I have come across some discussions on reducing the thickness of the spacer ring to make it focus to infinity. I can try to look them up in the morning...
12-13-2017, 11:06 PM   #3
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Could it be that someone has modified your lens earlier? It is easy to do by tuning the rear piece of the lens.
I would suggest checking your lens is properly build up. It's very easy and there's step by step videos in youtube. You don't need to blow the whole lens up right away. Just check the mount piece. I'm thinking it is not in it's right place.

But if it does not help. Building up the whole lens up all over again is not an impossible task. Been done it myself. Just be very careful.

https://youtu.be/au7AfYEf51M

Last edited by Supakatti; 12-14-2017 at 01:38 AM.
12-14-2017, 02:08 AM   #4
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Tair 11A

QuoteOriginally posted by Supakatti Quote
Could it be that someone has modified your lens earlier? It is easy to do by tuning the rear piece of the lens.
I would suggest checking your lens is properly build up. It's very easy and there's step by step videos in youtube. You don't need to blow the whole lens up right away. Just check the mount piece. I'm thinking it is not in it's right place.

But if it does not help. Building up the whole lens up all over again is not an impossible task. Been done it myself. Just be very careful.

How to clean up TAIR-11a lens - YouTube
Thank you for a quick reply.
I bought an used lens and so have no way to find out whether it was modified before.

Could you please share with me the Youtube Video as I am unable to locate that.

Strangely enough, it works well with Sony Mirrorless APSC - so flange distance does not seem to be the issue.
Any idea whether converting to K mount is possible and whether it is likely to sort out the infinity focus issue?

12-14-2017, 02:17 AM   #5
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QuoteOriginally posted by Nightsword Quote
The Tair 11-A lens (black version) I bought recently gives good results in terms of focusing sharpness up to 6 meters. It gets blurred beyond that, accompanied by lack of focus confirmation by K-1. I am using the Pentax original adapter for M42.

Rather strangely it works well in Sony Mirrorless that a friend of mine has.

Grateful for any advice on how I can make the lens focus to infinity since I like the lens in terms of both sharpness and contrast.
The Tair-11A has an exchangeable mount (hence the "A" designation). Often, it's the seating of the lens in that mount that is the cause of infinity focus problems. Try loosening the screws and ensure the mount is pressed hard against the lens before re-tightening them. If that doesn't work, remove the mount altogether and check that there is no debris, or poorly-machined areas on the rear of the lens or inside the mount that may stop them from mating together properly.

Another possibility - the most likely, IMHO - is that the thread on the mount hasn't been fully or properly cut (I've found this problem even on brand new, current production M42 lenses). If that's the case, it may not screw fully into the Pentax M42 adapter - but on your friend's Sony, the adapter threads probably have wider tolerances (many of them do).
12-14-2017, 11:27 AM   #6
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QuoteOriginally posted by Nightsword Quote
Strangely enough, it works well with Sony Mirrorless APSC - so flange distance does not seem to be the issue.
Based on comments on this site, it is not unusual for Sony-E adapters to be a smidgeon on the short side such that properly adjusted lenses may focus past infinity. Even so, you are correct that flange distance is probably not the issue. More likely is that the focus ring infinity adjustment has been tweaked to allow infinity focus on Nikon with a glassless adapter.


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12-14-2017, 11:42 AM   #7
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QuoteOriginally posted by BigMackCam Quote
Another possibility - the most likely, IMHO - is that the thread on the mount hasn't been fully or properly cut (I've found this problem even on brand new, current production M42 lenses).
That is shocking since such a lens would not seat properly on an M42 body and proper adapters have a generous cut to allow easier lead-in to the threads. I have a fair number of M42 lenses and none lack undercut below the threads or have flare at the base that exceeds the thread diameter.


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12-14-2017, 12:44 PM   #8
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QuoteOriginally posted by stevebrot Quote
That is shocking since such a lens would not seat properly on an M42 body and proper adapters have a generous cut to allow easier lead-in to the threads. I have a fair number of M42 lenses and none lack undercut below the threads or have flare at the base that exceeds the thread diameter.
My most recent experience was with a brand new, direct-from-factory BelOMO "Peleng" 8mm f/3.5 just a few months ago. It wouldn't screw all the way into one of my better M42->E-mount adapters, but - with some gentle persuasion - *would* screw in to a cheap-and-nasty adapter (that I got free with a lens some time back). That adapter has very generously-spaced threads that start a little way into mounting ring I can only think that the thread pitch on the lens mount was slightly incorrect, the threading wasn't completely cut, the diameter of the threads was slightly out, or the finishing was poor (even though it looked OK to me). I got a replacement mount from the manufacturer and it's perfect (on that note, the factory rep in Belarus was very helpful and responsive - I got an apology by return e-mail within an hour, the new mount was posted same day at no cost to me, and I received it a week later!!).

I've had this happen with a vintage lens too, though I can't now be certain which one. I'm pretty sure it was a Jupiter-37A (or possibly an -11A), as I remember I had another copy in poor condition that I used as a donor to replace the mount.

I guess there were and still are some factory duds that make it through Quality Control

12-14-2017, 01:37 PM   #9
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QuoteOriginally posted by BigMackCam Quote
I guess there were and still are some factory duds that make it through Quality Control
QC is for those with little imagination.

BTW, I am very impressed with the response from the factory. I guess there are advantages to buying direct.


Steve
12-16-2017, 06:33 AM   #10
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QuoteOriginally posted by BigMackCam Quote
My most recent experience was with a brand new, direct-from-factory BelOMO "Peleng" 8mm f/3.5 just a few months ago. It wouldn't screw all the way into one of my better M42->E-mount adapters, but - with some gentle persuasion - *would* screw in to a cheap-and-nasty adapter (that I got free with a lens some time back). That adapter has very generously-spaced threads that start a little way into mounting ring I can only think that the thread pitch on the lens mount was slightly incorrect, the threading wasn't completely cut, the diameter of the threads was slightly out, or the finishing was poor (even though it looked OK to me). I got a replacement mount from the manufacturer and it's perfect (on that note, the factory rep in Belarus was very helpful and responsive - I got an apology by return e-mail within an hour, the new mount was posted same day at no cost to me, and I received it a week later!!).

I've had this happen with a vintage lens too, though I can't now be certain which one. I'm pretty sure it was a Jupiter-37A (or possibly an -11A), as I remember I had another copy in poor condition that I used as a donor to replace the mount.

I guess there were and still are some factory duds that make it through Quality Control
Thanks a lot again, Mike.

Since my Tair 11A is not flushing with the camera body (it gets tighter beforehand), lens thread seems to be the issue. Is there anyway to fix that? Alternately, which cheap adapter should I buy?

---------- Post added 12-16-17 at 06:36 AM ----------

QuoteOriginally posted by IgorZ Quote
I have the silver version, and it also does not focus to infinity on k-5. I haven't tried to adjust it as I use it as a portrait lens. I have come across some discussions on reducing the thickness of the spacer ring to make it focus to infinity. I can try to look them up in the morning...
Have you had chance to check how to reduce the spacer in Tair 11A? Would be grateful for advice.
12-16-2017, 08:04 AM   #11
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QuoteOriginally posted by Nightsword Quote
Thanks a lot again, Mike.

Since my Tair 11A is not flushing with the camera body (it gets tighter beforehand), lens thread seems to be the issue. Is there anyway to fix that? Alternately, which cheap adapter should I buy?

---------- Post added 12-16-17 at 06:36 AM ----------


Have you had chance to check how to reduce the spacer in Tair 11A? Would be grateful for advice.
I have. Found the page I was looking for, but instructions are not great. The guy was more interested in comparing the lens to a Nikon lens, rather than explaining how he did it. I will look for a better explanation. In the meantime, there is a guy on youtube with a channel called Retro Photo House who has videos on how to fix just about any Soviet lens. It might be worthwhile asking him for an advice. He is good with responding to questions. His English is good too.
12-16-2017, 09:05 AM   #12
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QuoteOriginally posted by Nightsword Quote
Thanks a lot again, Mike.

Since my Tair 11A is not flushing with the camera body (it gets tighter beforehand), lens thread seems to be the issue. Is there anyway to fix that? Alternately, which cheap adapter should I buy?
You're very welcome

See below a photo showing how my Tair-11A sits against the mount of a Pentax ME Super. Does yours look like this when fitted, or are there extra gaps or bits anywhere?

Do other M42 lenses screw into your adapter without any problem? I'm wondering if there may be a slight mis-cut or damage to the adapter threads...

Have you tried fitting the adapter to the lens first, then fitting the lens and adapter combination to the body?

If you look at the inner threaded surface of the adapter, there's a small screw hole visible. Is the screw protruding through that hole? Or, do you see any rough edges to that screw hole? In both cases, this could foul the lens threads.

A couple of photos of the lens threads, plus another of the lens fitted to the camera (like my photo below) and screwed in as far as it will go, might help us in identifying the problem.

Assuming the difference between your setup and mine is a slight gap between the rear of the lens and the flush-fitting adapter / body mount, then you could try this:

Very lightly lubricate the lens threads with lithium grease (or some other fairly stable lubricant), then - with the adapter fitted to the camera - try mounting the lens and see if it will turn further this time, wiggling it gently side to side as you go. Also, try turning the lens whilst also pushing it gently in towards the camera. Try the same, but pulling the lens gently away from the camera. Sometimes, this can help with stubborn threads. Note - you want to avoid getting lubricant inside the camera, so if this does work, remove the lens and adapter from the camera and wipe away any excess before using it.

Feel free to PM me if you'd prefer
Attached Images
 

Last edited by BigMackCam; 12-16-2017 at 12:56 PM.
12-16-2017, 10:52 AM   #13
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Hi,
I have one Tair 11a and I am using it with original Pentax M42 to PK adapder ring. Works flawlesly. In case that there is an issue with the thread on the lens mount maybe the best solution is to change it. In the original Tair box there are two mount adapters T-M39 and T-M42 but there is T-PK or T2-PK mount adapter on the market and just forget about using M42-PK adapters any more on this lens. Here is a link about how it is done:
Tair 11A P/K fit

If I can help just message me
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