Help with me sigma 35-135 zoom lens

[Donavichcurtis]

ok first of all I'm new to the world of film.
And new here so excuse me if my question is being asked over and over.
Anyway I got myself a used/faulty sigma 35-135mm lens off of eBay for £4.50 as it had fungus on the inside lens. Me being me thought how hard can it be to strip down a lens and clean it (it was easy) but now I'm stuck with the aperture bayonet part, whatever I do to put that part back together results in the aperture blade not working properly :/ I will post photos soon if I can. Does anyone have any info as to why the aperture only works from say 11 rather than 3.5 like it's meant to.
Thanks

 

[albada]

Welcome to apug!
I doubt anyone here has repaired that specific lens, but I and others have repaired cameras and lenses, so we can give you principles. I suspect that this is a problem in misplacement. The aperture mech can probably be mounted in multiple positions, only one of which will work correctly. Also, the levers leading to the aperture must be positioned correctly, and it's sometimes possible to position one of them wrong as well. Good luck!

Mark Overton

 

[Donavichcurtis]

Thank you for the reply.
I wasn't sure if this forum was for the topic I had but thought I would ask.
I will have to look in to that possibility of mounting it wrong. Thankfully I now know that I didn't even have to take of the mounting plate to get at the inner lenses so if it needs work again I know to leave that it alone. I did put one of the levers in wrong so maybe I have got something else in the wrong place.
If I can't fix it then no matter as it only cost £4.50

 

[AgX]

Photos might be helpful, if there is someone here who worked on that mount.
We don't evehn know WHAT mount your are talking of. There are a great lot. Even the way the diaphragm actuator acts on the leafs is different between mounts.

 

[Donavichcurtis]

I will put photos on as soon as I've taken it apart again but for now it was just to see if anyone had the same lens or a history with repairing that lens

 

[Donavichcurtis]

These are the pictures I could get!

 

[albada]

Your second photo shows a tab with a long-head screw on the right. This likely should mate with a slotted tab inside. If they don't align, then this tab with push the side of the inside tab, and the aperture will be far wrong. This is one possible problem I see from the photos. Good luck, Mark.

 

[John Koehrer]

FWIW, it's an Olympus mount. The two silver tabs are for lens release and DOF.
The release will only work one lever in the mount. The DOF is likely to be the longer one.
Soooo, if you reach to the stop down linkage with a probe does it open & close properly?
If it does, you may be putting the long lever on the wrong side of the internal stop down lever.

 

[Donavichcurtis]

The long black lever has been going into the slot where the long pole goes towards the aperture blades, my big problem is which ever way I set up the levers nothing happens when I set the aperture to 4 and 5.6 but it all worked fine before I took it a part, well apart from there being oil I the blade and they took ages to shut!

 

[Donavichcurtis]

It's really bugging me now, surely it can't be that hard to do it. Someone probably did it in the factory when it was made :/

 

[albada]

That's why, when disassembling, I carefully note how the parts fit together before I took them apart. I hate being mystified when reassembling. Focus threads are like that: They will usually mate at several positions, only one of which is correct. Grrr!

 

[Donavichcurtis]

I did take a photo before I touched the mechanism but that didn't help much.