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Need help - disassembly Minolta 85mm D

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paso144 View Drop Down
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Post Options Post Options   Quote paso144 Quote  Post ReplyReply Direct Link To This Post Posted: 04 November 2019 at 10:41
bump
A850, 16fish-eye, 17-35G, 28-70G, 50/1.4RS, 58/1.2, 85/1.4D, 80-200/2.8APO black, 100macroD, 100-300APO, 100-400APO, AT-X304, 500mirror, 5600D HS.
 



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Rudy View Drop Down
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Post Options Post Options   Quote Rudy Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 04:29
If your theory is right, about removing the front element to the front, you could use thermal force, applying cold spray (with a thin plastic film to protect the glass), on the front glass element and the try to remove it. Sometimes helps.
Good luck.
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amrep View Drop Down
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 06:31
The marks on opposite sides of the barrel doesn't bode well. Someone very unskilled have been tinkering with this copy. From your pictures it looks like the marks originated from using some kind of wise. This is an obvious hint that force have been applied and the barrel got distorted.

In theory it could be possible to apply moderate force with a rubber protected wise 90 degrees from the marks and the front element may drop out.

However, the fungus or deposits behind the front element may in fact be one of the minor problems with this copy. If the lens is usable it may be best to leave it like it is.
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Rudy View Drop Down
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Post Options Post Options   Quote Rudy Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 07:35
Originally posted by amrep amrep wrote:

The marks on opposite sides of the barrel doesn't bode well. Someone very unskilled have been tinkering with this copy. From your pictures it looks like the marks originated from using some kind of wise. This is an obvious hint that force have been applied and the barrel got distorted.

In theory it could be possible to apply moderate force with a rubber protected wise 90 degrees from the marks and the front element may drop out.

However, the fungus or deposits behind the front element may in fact be one of the minor problems with this copy. If the lens is usable it may be best to leave it like it is.


You are right, looking at the state of the screws, there is an unskilled person been tinkering.....
How sad this happens to such nice lenses.
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Bob J View Drop Down
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Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 09:46
Is there a reason why the slot-head screw in the picture is still in place? Might that be retaining the front element?
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 11:55
If I remember correctly those two slotted screws under the rubber grip are for adjusting the focus hard stops. Don't touch them unless the focus needs to be adjusted or repaired.
 



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Bob J View Drop Down
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Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 12:24
Well, if that front group doesn't drop out, it is either being held in by a retaining ring (doesn't look likely), or some hidden grub screws, or the whole group unscrews anti-clockwise in a big thread.

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amrep View Drop Down
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 13:24
Unfortunately you are totally wrong.
The barrel with the front group is held by 4 (or 6?) pin screws with rollers in the "helix slots" of the (inner) focusing barrel. Those screws are accessible when you remove the outer barrel (the one with the distance window).
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amrep View Drop Down
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 13:24
I also have to make an important correction to my previous post. Those two silvery marks on opposite sides of the barrel could be mounting marks from the anodizing process and totally harmless. Difficult to judge fro the pictures.
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Bob J View Drop Down
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Post Options Post Options   Quote Bob J Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 13:31
Originally posted by amrep amrep wrote:

Unfortunately you are totally wrong.
The barrel with the front group is held by 4 (or 6?) pin screws with rollers in the "helix slots" of the (inner) focusing barrel. Those screws are accessible when you remove the outer barrel (the one with the distance window).


So I guess that the outer barrel has to come off backwards? So next step would be to remove the bayonet and start stripping from that end?

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amrep View Drop Down
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Post Options Post Options   Quote amrep Quote  Post ReplyReply Direct Link To This Post Posted: 16 November 2019 at 13:47
Yes, the outer barrel is removed from the rear.
But removing this will not help the OP alt all because the front elements can only be removed from the front.

The barrel (in fact it is shaped more like a bucket with a hole in the bottom) that holds the front elements also holds the aperture and the rear group (this group unscrews).

Edited by amrep - 16 November 2019 at 13:52
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paso144 View Drop Down
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Post Options Post Options   Quote paso144 Quote  Post ReplyReply Direct Link To This Post Posted: 18 November 2019 at 14:46
Thanks for all the comments, will study them and see what the next step needs to be. For now I feel I might screw it together again and just accept that there is some fungus on the front element and oil on the inner element

Edited by paso144 - 20 November 2019 at 15:25
A850, 16fish-eye, 17-35G, 28-70G, 50/1.4RS, 58/1.2, 85/1.4D, 80-200/2.8APO black, 100macroD, 100-300APO, 100-400APO, AT-X304, 500mirror, 5600D HS.
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