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Rob S
sage
Reged: 03/16/07
Posts: 410
Loc: NZ
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All,
Just got my 8x50 BA's back from the factory where they were fully serviced.
When I look in the tubes from the objective end, roughly 90 degrees clockwise from where the tube hinge is, there is a shallow, but relatively wide, hemispherical channel cut in the walls, running a good portion of the tube (i've attached a scan from a brochure - you can see the channel to the left of the red Leica badge).
http://img.photobucket.com/albums/v436/hcavn/bins.jpg
Now, this channel is wet with what I surmise is lubricant. I can see drops of the stuff, and they appear to be possibly slightly yellow. The wetness is not contained to the channel itself, it's a bit wider, though most of the droplets are in the channel.
Does anyone with a pair of similar glasses to these have this in theirs? It's easier to see the channels if the bins are focused to their closest distance.
They were back for service as there was a thumbnail sized discolouration/stain on the objective side of the internal focusing elements. I thought the water integrity had gone and it was getting invaded by humidity and fungus growing on it. Now i'm wondering if it was a drop of lubricant that fell on it and spread out? Any ideas? I don't relish the thought of a drop falling onto the elements. I assume that it's a relatively technical lubricant with no chance of vapourising at any same temperatures or pressure - so i'm not too concerned that that will be an issue.
The close-focus is now about 3 meters on these - I think they have removed some of the overtravel at infinity. Possibly they can retro-fit it to BN spec???
Regards,
Rob.
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8" f5 Dob with Feathertouch
Brandon: 16
Pentax: 7, 10 & 20XW
TMB: 30 Paragon
TV: 8 & 13 Ethos;
5 & 13 NaglerT6;
24 Panoptic;
Leica Trinovid 8x50 BN
Edited by EdZ (10/11/07 08:39 AM)
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Claudio
sage
Reged: 07/26/04
Posts: 226
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Rob,
In the cut-away it seems that the mount of the focusing lens moves without contact with the wall of the body.
If this is the case, in order to keep the lens aligned to the rest of the optical system, it is possible that the mount (probably pressed by a spring that however I don't see neither in your cutaway nor in these pictures ) skims the inner surface of the body just where is the milled channel.
For this reason the channel would be greased. If my guess is correct, the droplets should be mainly at the borders of the channel and at its end.
Just a conjecture, anyway.
Claudio
P.S. In those pictures the channel is visible only in the right barrel. Maybe in the left barrel the channel is on the diametrically opposite side of the barrel.
If this were true, the two small protuberances visible in the left focusing lens mount could be the two contact points of the mount with the milled channel.
As a consequence, if they skim the grease, droplets should stay mainly on two imaginary rails that are as distant between themselves as large are the contact points.
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KennyJ
Reged: 04/27/03
Posts: 10146
Loc: Lancashire UK
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Rob ,
This may be a bit of a long shot , but perhaps someone at the factory , such as the person who carried out the repairs for you , may be able to answer your queries ?
Just a thought !
Kenny
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If everyone is thinking the same thing , no-one is thinking - General George S.Patton
Zeiss 7 x 42 BGAT
Captain's Helmsman 7 x 50
Nikon 10 x 42 Superior E
Swift Audubon Kestrel 10 x 50
Helios 15 x 70 Observation
Strathspey 20 x 90
Televue 76 APO
Zeiss 85 Diascope
Helios 102 f5 refractor
Various eyepieces barlows tripods mounts etc.
Panasonic Lumix DMC - TZ5 digital camera
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Rob S
sage
Reged: 03/16/07
Posts: 410
Loc: NZ
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Claudio - i'm pretty sure nothing rides in the channel. The part of the focusing mount with the protuberances seems to contact the tube at another point - i'm sure I can see what appears to be a 'bearing' pad on it.
Kenny - i'll ask the agent if I get no joy on here.
Regards,
Rob.
--------------------
8" f5 Dob with Feathertouch
Brandon: 16
Pentax: 7, 10 & 20XW
TMB: 30 Paragon
TV: 8 & 13 Ethos;
5 & 13 NaglerT6;
24 Panoptic;
Leica Trinovid 8x50 BN
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