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Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 65
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 11, 2011 - 03:31 pm: | 
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I recently bought a Vivitar S1 28-105mm in Canon FD mount. It's in just about mint condition, except for one issue: the aperture iris blades are thoroughly coated with oil. The seller has a money-back guarantee, but I've owned a copy of this lens before and liked it a LOT so I'd just as soon keep it and clean the iris blades. I've done this recently with an older S1 24-48mm zoom, also in Canon FD mount, and it was easy to get the rear optical group out such that I could access the iris blades.
But with this lens, I have to remove the rear mount in order to remove the rear group. I've already unthreaded the group, but the mount has a restriction -- or the group has a bulge, one of the two -- such that the group won't pass through the hole. So, I need to remove the mount.
I've taken the FD breechlock ring off, and removed the four phillips screws holding the mount in place. But there is something catching somewhere. I can lift the mount free of the back of the lens, but it feels like one of the aperture linkage arms is caught and won't disengage. There are springs visible that provide the spring loading for these arms. At least one can be removed by removing the slotted screw that it is attached to, but I don't think this is a proper way to proceed.
I've been very gentle with wiggling about the mount because I don't want to bend or break anything, or have parts go *sproing!* and go flying across the room, only to disappear and never to be found again.
So, any suggestions on how to free up the mount's linkage so I can remove it from this lens? Many thanks in advance! |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 67
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 11, 2011 - 04:22 pm: |
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Just a brief follow-up. Thought of something else after the editing time window had expired, so I get to make another post.
The Vivitar S1 28-105mm f/2.8-3.8 is an update of the S1 28-90mm f/2.8-3.5. It is made by a different manufacturer than the 28-90 (09 code vs. 28 code, so that means Cosina vs. Komine), but outward appearances, apart from a restyled rubber grip, appear identical. I do not know, however, if the mechanical internals are the same. I have a 28-90mm f/2.8-3.5, but it is in Nikon mount, so the rear of the lens is different. But just in case the earlier and later variations in C/FD have the same mechanicals, I thought I should mention this, just in case you might have experience with the 28-90, but not the 28-105. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 69
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 14, 2011 - 12:19 pm: |
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Anybody? Help? |
Aliasant
Tinkerer
Username: Aliasant
Post Number: 2
Registered: 03-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 14, 2011 - 12:49 pm: |
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I wish I could help but I have a similar problem that I gave up on.
I have a Viv S1 28-90 nikon mount that i tried to fix but I couldnt find a good way to get the mount off.
I did get to the aparture blades but only after dismantling the whole lens more or less.
I did go from the front and had to remove the focusing mechanism. Probably the hardest lens I have ever attempted to fix...... which I didnt. I screwed it back together but lost interest. It was in to bad shape. |
Gez
Tinkerer
Username: Gez
Post Number: 247
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, January 14, 2011 - 02:40 pm: |
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Most zoom lenses are not designed to be attacked via the front or rear optical groups. Moving the front glass can potentially change the infinity focus at maximum focal setting. Trying to remove or unscrew the rear group can de-centre the iris mechanism as these components are often factory aligned and not meant to be moved.
The secret is to separate the lens into 2 parts by releasing the set screws hidden under the focusing grip.
Many Vivitar S1 35-85mm lenses seen at camera fairs have been subjected to amateur repair and are next to useless. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 70
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 08:32 am: |
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Thanks for the feedback, Gez. The Series 1 24-48 that I had apart for this same issue had its iris blades located in a separate "barrel" from the optical groups, the rear one which just threaded into this barrel. Don't really see how the iris could have been decentered, and it in fact wasn't, after I got the lens back together. So, like I mentioned above, it was really a simple operation accessing the iris blades in that lens. Not so with this one, though.
Is this approach of yours -- releasing the set screws under the focusing grip -- pretty much universal to the Vivitar S1 zooms? I'm willing to give it a shot, but I'll be frustrated and disappointed if I find that I've just opened up a bigger can-o-worms by doing this. |
Gez
Tinkerer
Username: Gez
Post Number: 249
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 15, 2011 - 09:44 am: |
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I struggled with two S1 24-48mm zooms, FD and OM mounts, until finding the Kiron Kid's web site, boggys.co.uk, where he has a complete service manual for the S1 70-210mm Mk1 version. Reading that provides a good introduction to most Vivitar zooms. The 35-85mm appears to be an exception in that it uses an older style of construction requiring a lot of fine adjustments with a centering microscope. Even most professional repairers would be out of their depth working on that lens.
The secret of the 24-48 is to roll back the focusing grip to reveal the focus limit roller and its 2 sets of 3 closely grouped screw holes. These provide adjustment for the travel of the focus collar. Unscrew the roller and turn the collar until it separates from the outer helicoid, make a note of this position. The lens is now in 2 halves and the iris unit is easily accessible for cleaning. The 3 screws holding the iris unit don't appear to have any centering function but the unit's exact placement with respect to the actuating levers on the mount will determine the consistency of the aperture values, this is critical for the FD mount so it is essential to scribe the unit's position before it is removed for cleaning.
In my case I was unwilling to separate the whole rear lens group from the iris unit and so I just cleaned the blades with cotton tips. Needless to say the sticky blade problem has reappeared so I have to redo it thoroughly....sometime.
The downside to this approach is having to re-thread the helicoid. It is no big deal if you are patient and marked the point where the collar separates. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 71
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 16, 2011 - 11:34 am: |
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Well thanks for the more in-depth procedure on the 24-48, and if I have occasion to take it apart again, I'll refer to the steps you mention. But I have my doubts as to whether your instructions for the 24-48 will do me any good with my 28-105.
At another forum, a fellow I know who works on lenses has just informed me that really the only way to get to the iris group on this lens is by removing the front components. So, almost a complete dismantlement seems to be the way to proceed with the S1 28-105. |
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