I have to say this RMC Tokina 80-200 f/4 lens in Nikon AI mount was probably worth the $1 it cost me. It has been at least $1’s worth of fun playing with it over two days
As you can see in the side view it almost appears as if the lens was dropped sideways onto gravel. The metal has gouges out of it that ruin the fine finish. But that isn’t the worst problem.
I haven’t figured out a great way to show you the internal deposits on the furthest back (closest to the camera) lens assembly. It looks like multiple small oil droplets around the edges on the surface closest to the back with larger smears on the internal facing surface of the same assembly.
I have only tried disassembling larger zoom lenses a couple of times, and always regretted the attempt. Some zooms come apart from the front back. That means cleaning the front element is relatively easy. But then you hit a complete subassembly that pumps front and back—coupled to the one-touch zoom ring—that blocks your access to that rear-most lens subassembly. Since that rear-most subassembly is exactly what has to be accessed to clean you are faced with a complicated procedure with multiple chances to lose the exact positioning all the bits require.
So after mulling it over for awhile I decided to consult with experts on the internet. I was watching the taking down of a lens similar to this one. It was speeded up because the actual process took 3.5 hours! Very early on it startled me to see the man take the lens mount off (three screws) and then calmly unscrew the very assembly I needed to clean.
Of course I had to at least try to copy his actions as far as getting that back assembly off. The first problem was getting the mount off. Once the three screws were removed, much to my surprise a very small protruding part of the lens body interfered with simply pulling the mount straight off. The baffle that extended from the back of the assembly I was trying to remove fit so close to the lens mount there wasn’t room to tilt the lens mount away from the protrusion.
I noticed the baffle has two notches for a lens spanner. They are very small and very thin located 180º opposite each other. Not having a lens-spanner of any kind I started by using a finger nail and a thumb nail. I can’t say there was no damage to the nails—or no bad words were said—but the assembly started to turn. It got easier to turn the farther it came out. It became easier to spin the assembly when you pointed the mount end straight down. In that position the assembly came loose and dropped down into my turning fingers.
I also found the lens mount could now fall off. It was just a couple of minutes polishing and the view through the assembly cleared up a lot. Then I managed to figure out how the lens mount had to fit back into the back of the lens. I replaced the three screws. Then I again turned the lens so the mount was pointing straight down and pushed the lens assembly back up into the lens. You can tighten the assembly in with finger tips—not having to engage the lens-spanner notches—until 90 per cent of the tightening is done. Then you have to sacrifice more nail material.
In an aside, I was thinking you could use a soft eraser, a pliable soft small ball or even a cut piece of plastic (the kind used in blister-pack packaging) the exact size to fit the notches but not protrude far enough to interfere with the lens mount to help with the tightening down.
Was the repair a complete success?
Not perfectly. The rather large black spot and some swirl of oil are gone. On close examination the small spots around the circumference are still there. I would have to actually take that back lens assembly apart to get to the area with the deposits. It seems feasible except for a couple of points—
The internal elements may simply drop out one after another—I expect with spacing rings, but then it gets really dicey
What if a whole stack comes out and collapses into a pile of parts (good luck with figuring out even which way the pieces face)
There is a terrible lens element requirement called centering. Even if you get the elements back you should try to have them in the same orientation to each other. If all the elements had a line from their centers to the outside edge at 12 o’clock, they should be replaced in exactly the same way to line up all the 12 o’clock lines.
Strangely the lens works fine mounted on a camera. It even appears sharp and clear. But you should always be aware any bright light in the frame will possibly cause a flare inside the elements. Of course, in some portrait circumstances or ethereal scenics this internal flare could be wonderful!
I did get a rear lens cap, so it wasn’t a complete waste of money!
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