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Jbh_stl
Tinkerer
Username: Jbh_stl
Post Number: 1
Registered: 11-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, November 01, 2006 - 02:54 pm: | 
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I have a Sigma 16mm f/2.8 fisheye lens with a Nikon mount. It's manual focus, and I'm guessing it was manufactured sometime in the 1970s (?). It has internal filters (blue, yellow, orange and clear), if that helps place it. I bought it used in 1989, and it worked fine until a screw came loose inside somewhere and prevented the focusing ring from turning.
I actually took it apart several years ago, all the way down to removing (inadvertently!) the iris blades, and thought I had it back together OK. But eventually it started to "rattle", i.e. the front lens would wobble in front of the silver Nikon mount (adapter?). About the same time, the aperture ring also lost its "click" and just kind of slid.
So last night I said enough's enough. I took it apart again, figuring if I did it once, I could do it again. However, the problem seems different this time. The wobble/rattle is caused by three tiny screws in the metal cylinder that holds the little lever that opens & closes the iris blades. I think they're loose and need to be tightened. The problem is, I can't, for the life of me, figure out how those screws were ever inserted! I can see the bottom of them, but not the head.
There's probably more precise names for these pieces; I hope you will forgive my ignorance.
Anyone out there familiar with this lens? Any suggestions how to tighten this thing back up and get rid of the rattle?
Any help you can provide would be most appreciated. Thanks.
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Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 96
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, November 02, 2006 - 08:55 pm: |
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First let me warn you that I am not familiar with this lens, so I am just making this up. Use it or not at your risk.
In the far right photo, I think I see screws in the knurled outer ring. Have you removed these? If so, was it then possible to remove the knurled ring to the rearward? It might either lift off or unscrew after loosening the set screws. |
Glenn
Tinkerer
Username: Glenn
Post Number: 87
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 03, 2006 - 04:30 am: |
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Like Rick I do not know this lens, however I have worked on a number of Sigma lenses and think I understand their design philosophy. For all mount types the basic optical cell/focus barrel is the same, as is the aperture linkage. The individual mounts are just 'hung' on the back of this complete unit. This mount unit contains all the required linkage to transfer the aperture operation, from camera to lens and any 'registration' corrections required. There may be very simple additions - an actuating lever - added to the main unit, but nothing drastic.
Commonality is the only way that lens manufactures can keep their costs down. I know the inclusion of molded plastic parts is also quoted, but a vast parts inventory is a recipe for disaster in the third party lens business. This is especially so if you are producing lenses which have excellent optical performance, something that Sigma has always striven for. |
Mikel
Tinkerer
Username: Mikel
Post Number: 8
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, November 03, 2006 - 08:37 pm: |
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I think this might be a "YS" mount lens. Is it marked "YS-N(something)"?
If so if have owned one for 30 years or so and might be able to help.... |
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