Tokina AT-X 80-200 / 2.8 Infinty focus problem

Lloydy · Expire: 2022-01-01

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 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.

Is it a DIY option to set infinity on a camera, 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.

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

I've dismantled and re-assembled quite a few zooms, but never the Tokina 80-200/2.8. It seems like every zoom is different, although there are certain design principles most follow. In all instances, I have never run into an issue where lens groups needed to be adjusted to each other. Not saying that this adjustment doesn't exist, but if it does, chances are there are a set of screws that are locked down tight which control this, that don't otherwise need to be messed with. Does this lens show any signs of being dismantled before? If so, when it was reassembled, the focusing helical may have been threaded on one thread away from where it should be. I've run into this situation several times when reassembling a lens. Where I marked the pieces before disassembly, only to discover that the way I marked them wasn't the way I should have, then had to rethread the helical by trial and error to get infinity focus back. It's somewhat tedious and time consuming, but this is the only way I know, short of modifying the base somehow, to adjust infinity focus on most lenses. Hopefully, somebody with more experience than me will add their experience to this thread.

Lloydy · Expire: 2022-01-01

I think it might have been tampered with / adjusted in the past, if you look carefully at the front element shot the moving group inside has a pair of spanner slots on it ( one is just visible in the picture ) that seem to have been used.

I don't think it's a helicoid out, infinity is not far away.

At 200 and stopped right down I get this -

but at 80 and wide, it's as bad as this.

up to infinity it's sharp, I really like this lens and want it fixed, I might even spend money and get it fixed. Shocked

This was at 200 and 1/200, hand held, and the clock is high up on a roof - damn near infinity.

It would be a shame to lose this lens.

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

I agree. That last shot shows the performance capabilities of that lens. I own a similar model -- the 100-300mm f/4 SD, and I like mine a lot. It does a better job at 300mm f/4 than my old Canon FD 300mm f/4 tele did.

Correct me if I misunderstood, but it looks like the lens has worse infinity focus problems at 80mm than at 200mm. If this is the case, then something is off internally. It's possible that something fell out of adjustment or position internally to cause this, but I wouldn't have a clue as to what until I dismantled the lens.

You might want to post a question about this over at KY Photo. There are quite a few good repair folks who hang out there. Go here and then click on Maintenance and Repair. You'll have to register to post a message.

http://www.kyphoto.com/cgi-bin/forum/discus.cgi

Lloydy · Expire: 2022-01-01

Ah yes, I'd forgot about that forum. I think I am already signed up.

http://www.kyphoto.com/classics/kironlens.html

could this be a similar design of lens ? It looks very close. Confused