I was very surprised by such mounting. With my new acquainted sample it had failed.
It is a Vivitar 28-200mm F3.5-5.3 zoom lens.
I realized that seemingly the rubber bandage has shrunken in width as there is a slit between it and a rim at the operating barrel ring. Rubber bandages typically do not shrink, what made me wonder.
Also at the zooming scale there was no 200mm engraving. Not actually neccessary, but as there is an effectice aperture mark in green next to the aperture ring, one would expect the respective zoom figures to be colour marked respectively. There was not.
First idea then is a mechanical fault that would allow the assembly to elongate enough to reach the end position.
However the final position yielded the right image angle for 200mm. Also just at that end position the macro fearure could set on by twisting the operating ring beyond an otherwisde active stop. Thus all as normal.
After flipping over the bandage it turned out that the distance-scale ring is a seperate part, fitted to the operating barrel ring by means of as very petite circular flange. These flanges doe not yield chances to srew on that focus scale ring. Thus it was just held in place by a circular adhesive tape.
Over time and due to hand pulling force at a circular rim at the distance-scale ring it slided down and no langer gave view on the actually engraved 200mm mark. There had not bee a lateral movement of that ring though.
So a very simple explanation. And a simple reapair: just adjusting the ring at the infinity mark and fastening it again with adhesive tape.
BUT I dislike such fastening as it hat proven to fail over time. The craftsman legitimate way would either be to glue that flange (what seemingly will hamper further disassembly), or to screw fasten the distance-scale ring.
As said the flange parts are too petite to set screws in. But inside the operating barrel is a brass plate sufficiently thick to have been screw fastened. It is protruding over the flange area to act as stop for the macro function. This brass plate is ideal to screw fasten the distance scale to. However that would only be one mount at one side, leaving the distance-scale ring to wobble. With careful working it should be possible to bend in form a second brass plate fitting exactly inside the operating barrel at opposite side and srew fix it without further disassambly of the lens. Having let this second plate protrude as the original one would make a second fixture for the distance-scale ring.
This is the first time I see such taped mounting. The lens was made by Kobori.
http://allphotolenses.com/public/files/img/a8ba682dce4fee1c65cc989433ff6c8f.jpg
It is a Vivitar 28-200mm F3.5-5.3 zoom lens.
I realized that seemingly the rubber bandage has shrunken in width as there is a slit between it and a rim at the operating barrel ring. Rubber bandages typically do not shrink, what made me wonder.
Also at the zooming scale there was no 200mm engraving. Not actually neccessary, but as there is an effectice aperture mark in green next to the aperture ring, one would expect the respective zoom figures to be colour marked respectively. There was not.
First idea then is a mechanical fault that would allow the assembly to elongate enough to reach the end position.
However the final position yielded the right image angle for 200mm. Also just at that end position the macro fearure could set on by twisting the operating ring beyond an otherwisde active stop. Thus all as normal.
After flipping over the bandage it turned out that the distance-scale ring is a seperate part, fitted to the operating barrel ring by means of as very petite circular flange. These flanges doe not yield chances to srew on that focus scale ring. Thus it was just held in place by a circular adhesive tape.
Over time and due to hand pulling force at a circular rim at the distance-scale ring it slided down and no langer gave view on the actually engraved 200mm mark. There had not bee a lateral movement of that ring though.
So a very simple explanation. And a simple reapair: just adjusting the ring at the infinity mark and fastening it again with adhesive tape.
BUT I dislike such fastening as it hat proven to fail over time. The craftsman legitimate way would either be to glue that flange (what seemingly will hamper further disassembly), or to screw fasten the distance-scale ring.
As said the flange parts are too petite to set screws in. But inside the operating barrel is a brass plate sufficiently thick to have been screw fastened. It is protruding over the flange area to act as stop for the macro function. This brass plate is ideal to screw fasten the distance scale to. However that would only be one mount at one side, leaving the distance-scale ring to wobble. With careful working it should be possible to bend in form a second brass plate fitting exactly inside the operating barrel at opposite side and srew fix it without further disassambly of the lens. Having let this second plate protrude as the original one would make a second fixture for the distance-scale ring.
This is the first time I see such taped mounting. The lens was made by Kobori.
http://allphotolenses.com/public/files/img/a8ba682dce4fee1c65cc989433ff6c8f.jpg
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