Tokina AT-X 80-200 / 2.8 not reaching infinity

[lloydy]

My Tokina AT-X 80-200 / 2.8 won't reach Infinty focus, it's definitely not going past, it's not getting there. I have about 8 other Minolta MD lenses and they all reach infinity on my Sony NEX ( Fotga adapeter ) perfectly, and I've tried them on both Minolta XD7's and they are fine, but the Tokina is short on the XD7's as well.

If the lens has been tampered with / adjusted before I don't think it's been reassembled with one thread of the helix out, infinity is close, but definitley not reached

Is it a DIY option to set infinity on a lens such as this, or is it a job for a tech' with a collimator ? I have read about one touch zooms being difficult to adjust, they require the front and rear element packs to be adjusted to each other?
Or can I slacken the barrel off, find infinity and then lock it back down?

I've peeled the rubber off for a look, and there are lots of screws on view, and I don't want to wreck this lovely lens. Up to the point it loses focus this lens is superb and focus' really sharply.





I don't think the screws inside the slots have anything to do with infininty,or do they ?

[Stephen]

That's going to be complex to adjust, an expert lens technician will be needed, but just how far is it wrong? As long as the image is in focus, all nearer settings work, and at full stretch DOF should cover things. If sharp shots at full aperture fail at under 100 feet then it has problems, but if it is sharp at 100 then it is not worth the trouble of adjusting. Many lenses do not focus to infinity, which is 1000 foot plus in practical terms. The Moon is the best really accurate test, but the tiny differences around 100 feet barely matter at normal apertures.
If the lens is focused at, say, 10 feet, then that's it, it is as accurate as any other lens. However the miss adjustment may indicate other issues, out of place internals, out of collimation,(centring), general damage due to a drop, or simply poor assembly from new.
Stephen.

[lloydy]

Thanks for the advice Stephen, I understand what you're saying here - more or less - but I think there is a fault rather than just a 'bit of softness at infinity'. I use it on my Sony NEX with focus peaking and focus assist - magnification, and I get good results with all my lenses using this method. This lens shows focus with the focus peaking, but that is not 100% easy to detect to the naked eye from the screen.
Up to anything before infinity it is stunning -

This is hand held at 1/200, the clock is a good distance away and I think the zoom was at 200mm


But this picture was shot at 1/250 on a solid tripod, I can't remember the aperture but I shoot at the closed end wherever possible, especially landscape on a tripod.

Nothing at all is in focus from front to back,I think this was towards the 200mm end, certainly not the 80mm end anyway.

It's not just blurred, it's got a smudged appearance - not so obvious in this picture but some look as though they are amateur water colours!

I'll test it better tomorrow with something in the foreground and a building in the distance, run through apertures and zoom range.

The sharpness and quality I get when it behaves is superb, and I really think it could deliver at infinity, especially seeing other peoples pictures on forums and flickr.
The lens cost me £5 so I won't be too upset if it is knackered, but for £5 I would also spend a reasonable amount to get it fixed properly if it was a simple fix for a repair man.

[mickeyobe]

Mar 12, 2013 18:29:46 GMT -5 lloydy said:

Thanks for the advice Stephen, I understand what you're saying here - more or less - but I think there is a fault rather than just a 'bit of softness at infinity'. I use it on my Sony NEX with focus peaking and focus assist - magnification, and I get good results with all my lenses using this method. This lens shows focus with the focus peaking, but that is not 100% easy to detect to the naked eye from the screen.
Up to anything before infinity it is stunning -

Just a wild guess but is it possible that it is focussing beyond infinity?

Mickey

[lloydy]

No it isn't Mickey, unfortunately. I'm used to that with the amount of old lenses I use on my Sony NEX and Pentax K10.
This lens is Minolta MD fit and I've tried it on the two Minolta XD7's I've got, without film, and the excellent focusing screen in both these cameras show that it definitely isn't reaching infinity, so I've pretty much ruled out the MD to NEX adapter and the NEX.

[mickeyobe]

Mar 13, 2013 18:40:12 GMT -5 lloydy said:

No it isn't Mickey, unfortunately. I'm used to that with the amount of old lenses I use on my Sony NEX and Pentax K10.
This lens is Minolta MD fit and I've tried it on the two Minolta XD7's I've got, without film, and the excellent focusing screen in both these cameras show that it definitely isn't reaching infinity, so I've pretty much ruled out the MD to NEX adapter and the NEX.

Lloydy,

As a matter of curiosity what would happen if you focussed at the hyperfocal distance?

Mickey

[lloydy]

yes, that could be interesting Mickey. I shall get the big tripod out and test the thing properly, and take hyperfocal into account.
I'm pretty sure it is faulty, why else would a lens like this in excellent cosmetic condition be in a box of junk and sold for £5 at a camera fair? They see me coming a mile off.

[Deleted]

The Tokinas were great lenses. I have a MF Tokina 80-200 f/2.8 zoom that produces great results with my Nikon D300--and it's fast enough that I can afford to lose a stop or two by adding extender.

[lloydy]

Over the years I've had a few Tokina's, mainly auto focus zooms, and I've had no luck at all with them, I've got two at the moment and neither work properly. I've always had far better results and reliability from Tamron.

I think I've bodged this manual focus AT-X to get infinity, at the moment it goes a long way past. Which is better than not reaching it. But it did involve drilling holes and moving the focusing barrel around, I just need to drill yet another set of holes and move it back a tiny bit. But it's a cheap lens that would otherwise be a dead lens, so I'm not feeling guilty.
I'm hoping to get a useable lens out of it because optically it's stunning, and makes a very good walkabout lens on my Sony NEX, to me it's a keeper so I'm not bothered about perfection.