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Stingom
Tinkerer
Username: Stingom
Post Number: 1
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 23, 2007 - 01:47 pm: | 
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Hi,
Does anyone have any experience with fixing a Tamron 35-70mm Zoom Adaptall 2 lens?
http://www.adaptall-2.com/lenses/17A.html
http://freenet-homepage.de/stauber/mamiya-nc/m42_tamron_35-70_3.5.htm
I bought this lens from eBAY recently. I tested this lens on my E-300 and OM-4. Unfortunately, focus to infinity was not possible. I checked the DOF scale. At infinity, the DOF reading was at 0.3m. There was no problem focusing within 2m distances. But beyond this, it is out of focus.
When focused at a very distant object, I could not get the image in the split screen to line up on OM-4. The same is the case on the E-300, as I can't get a sharp picture at infinity focus on the matt screen. I did actually take a photo when focused at infinity with the E-300. But the picture was out of focus. At infinity focus, the lens barrel is at its shortest at 70mm setting. The DOF reading was aligned at 0.3m instead of infinity. See photo below, you can see what I mean. If you compare this picture with the one posted on the web (Adaptall II site), you will clearly know there is something is wrong.
I looked at the back of the lens barrel (see picture 2 with arrow) I can see some minor scratch marks on the retaining ring which I think holds the front lens barrel together. I wonder then if this is where I should do the adjustment?
http://i168.photobucket.com/albums/u161/stingOM/Tamron35-70mm.jpg
There is a retaining O-ring where the arrow is pointing.
http://i168.photobucket.com/albums/u161/stingOM/Tamron35-70mmwitharrow.jpg
Compare my photos with the images shown this site.
http://www.adaptall-2.com/lenses/17A.html
You should be able to notice that the focus is at infinity with a working lens, whereas with mine it is at 0.3m!
The first photo was taken at the 35mm setting. The second photo was taken at 70mm setting. The out of focus problem is a lot more severe at the 70mm end.
http://i168.photobucket.com/albums/u161/stingOM/Tamron1.jpg
http://i168.photobucket.com/albums/u161/stingOM/Tamron2.jpg
Can anyone recommend a DIY job for the repair?
Thanks,
Simon |
Tpe
Tinkerer
Username: Tpe
Post Number: 3
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 23, 2007 - 03:07 pm: |
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I am sorry i cant tell you how to do it on that specific lens, but in principle it is quite easy.
The focus helical needs to be rotated in relation to the sliding lens, so as it has traveled further when infinity is reached. You say there is an O ring, would this allow the front half of the housing to be rotated in relation to the back half in any way? On the lenses i have done this with they have been seperable under the rubber focusing or zoom ring occasionally just taped together. What you have to do is reassemble the lens, mount it, focus to infinity looking through the lens, then turn the ring so as it also reads infinity, and fasten the front and back halves so as they nolonger rotate in relation to each other.
Perhaps a similar thing is possible with the tameron?
tim |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 122
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 25, 2007 - 12:30 am: |
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Hi Simon, what you write about ebay puchases sounds familiar; I once bought a 28-135 zoom lens that had similar problems. It had obviously been apart and wrongly put together again. After fumbling about on some cheap lenses ("actions speak louder than words") I discovered for myself what Tpe describes in the second part of his post, it is more or less a matter of trial and error and has worked out fine on my Tamron zoom, W. |
Stingom
Tinkerer
Username: Stingom
Post Number: 2
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 25, 2007 - 12:10 pm: |
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Thank you very much to both for replying to my enquiry. I shall have a go when I get a chance.
Best regards,
Simon |
Robertofollia
Tinkerer
Username: Robertofollia
Post Number: 10
Registered: 04-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 26, 2007 - 04:28 am: |
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My tamron 28-70 adaptall 2 model 59A developed the same problem. Yours I think it's an older model (all metal) than mine.
On mine, I removed the rubber grip from the focusing ring. Both sides of the focusing ring were held by tape. I removed the tape, pointed the camera at a distant subject, turned the free focusing ring to the desired position, then aligned distance scale with the focusing ring, put the tape back and done!
If yours is plastic, this will be the way. If it's metal, it will differ a little bit.
Hope that helps
Good luck!! |
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