Near-sighted Vivitar 135mm lens

[VichySchwa]

Hi Everyone - I just got a TX 135mm F/2.5 from Goodwill yesterday and the lens is almost flawless - there are no scratches but there's a small flaw that seems to be noticeable when I reflect natural light just right on it - almost like a smudge on the coating that isn't going away with IPA. But that of course isn't my main concern...

I started taking a few more pictures in earnest this evening and I'm discovering that the lens appears to be near-sighted. I hit infinity when I'm focusing on something that I'm estimating is 30-40 feet away and I can't get it in focus, and I can't get anything to focus sharp beyond that. It's got a screw mount adapter, I was trying it out on a Sony A6000 with a K&F M42-NEX adapter when I discovered it wouldn't focus to infinity. To rule out the adapter I placed the lens on a Mamiya 1000 DTL as well as a Yashica TL Electro and a Pentax Spotmatic SP, and the same thing is happening there. I'd like to use this as more than just a close-focusing lens. (Edit to add...) I also tested a known good 200mm Vivitar screw mount on the same K&F adapter and it works fine.

I took the following test picture with the Sony, wide open at 72 inches with a tape measure going from the subject to the camera, and roughly placing as close as I could to the sensor plane at the 72 inch mark, I focused, and took the following shot. The distance measurement on the lens when it was in focus was more like 6.3 feet (between 6 and 7, closer to 6). When I put the lens back on the Mamiya and did the same focusing, it was roughly in the same place (between 6 and 7).

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My questions...

Is the TX adapter a possible problem? I don't have an alternate TX adapter (for my A6000 I have Minolta, Nikon, and Konica adapters) to see if it's a problem with the TX adapter, and I have a T4 adapter for a few other lenses and it seems like it would fit as this is a 1st gen TX lens, but I'm concerned it's not going to work properly and don't want to try that.

It seems like the calibration of focusing is the problem. Is the disparity of minimum focus a clue? How do I calibrate this? I'm not necessarily shy about opening up the lens as I've opened up a 28mm Vivitar before to clean up elements and goofed up the lens order, but fixed that, and I've removed gunk off of aperture blades on a Konica and Rokkor lens. What would I look for if I needed to open it up? Thanks

[VichySchwa]

Adding 2 more pictures. both pictures are focused to infinity, but first one is with smallest aperture of f/16, and the second is with the widest aperture of f/2.5.


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First picture is clearly sharper but still not in focus, and second there is nothing at all in focus.

[stevemark]

Just for clarification: If the object is - let's say - 20 feet away: Are the images sharp if you use the lens wide open (f2.?

S

[VichySchwa]

I forgot to track this thread and was wondering why I didn't see any notification of replies

I set up a subject and set my lens at 20 feet and moved myself until it was in focus. It looked like it was more like 10 or 15 feet but I didn't have a tape measure this time One is wide open at 2.5 and the other is all the way down at 16. I set ISO to Auto and shutter remained the same at 1/2000.

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