Sigma 105mm macro lens - aperture blades stuck - any ideas?

Carlh

Carlh

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Carl
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Hi,

Before I either try DIY or send it off, I was wondering if anyone had experienced stuck-aperture blades. Im a bit disappointed, the lens is out of warranty (by about 18 months) and I've probably taken less than 5,000 shots using it. Shooting fine one moment, next moment, aperture wont open back up (though the camera says aperture is fine, i.e. I can change my aperture on my canon without an issue. The blades are locked at probably F14 by the looks, its pretty closed up.

have tried: swapping lenses on camera to see if it was the camera.
Switched the camera off and on again lmao
Switched lens onto different canon bodies, still the same - so i know its the lens.


Cheers (y)
 
•


At the bayonet, Carl, there is a lever that moves the
diaphragm to the desired position. Try setting the ƒ
stop at 22 or 16 with the lens unmounted and play
with the lever. If nothing happens, try the largest o-
opening.
 
Carlh said:
the camera says aperture is fine, i.e. I can change my aperture on my canon without an issue.
Click to expand...
I'm a little confused... is it affecting exposures?

It is possible to remove the lens with the aperture stopped down, but it requires a little trick so it's not likely.
 
Last edited:
Kodiak Qc said:
•


At the bayonet, Carl, there is a lever that moves the
diaphragm to the desired position. Try setting the ƒ
stop at 22 or 16 with the lens unmounted and play
with the lever. If nothing happens, try the largest o-
opening.
Click to expand...
I don't think so w/ canon digital...
 
Carlh said:
Hi,

Before I either try DIY or send it off, I was wondering if anyone had experienced stuck-aperture blades. Im a bit disappointed, the lens is out of warranty (by about 18 months) and I've probably taken less than 5,000 shots using it. Shooting fine one moment, next moment, aperture wont open back up (though the camera says aperture is fine, i.e. I can change my aperture on my canon without an issue. The blades are locked at probably F14 by the looks, its pretty closed up.

have tried: swapping lenses on camera to see if it was the camera.
Switched the camera off and on again lmao
Switched lens onto different canon bodies, still the same - so i know its the lens.


Cheers (y)
Click to expand...

Is it affecting your shots at all, Carl

something in my mind is saying that the 105mm macro is always like that until you take the shot ....... I only have the Nikon though
 
BillN_33 said:
Is it affecting your shots at all, Carl

something in my mind is saying that the 105mm macro is always like that until you take the shot ....... I only have the Nikon though
Click to expand...
On most Nikon lenses (non- E type) there is an aperture lever w/ a return spring attached... the spring holds the aperture blades stopped down to max when not attached.

On modern Canon lenses (non-FD) the aperture is controlled completely electronically. Normally, when removed from the camera they retain the last aperture setting which is normally wide open (for AF/metering). To get them to hold a smaller aperture (i.e. for reversed lens macro) you can remove the lens while DOF preview is active. I suppose they might hold a stopped down aperture if removed while live view is active and it has exposure preview functionality.
 
Last edited:
Thats weird. I just went to take another look at the lens at its opened wide again (the blades aren't closed).

Before today, I took the lens off while the camera was on, with F2.8 showing on the back-display of the 6d and replaced it back on, nothing was changed.

Basically looking through the viewfinder, it was almost pitch dark because of the aperture blades being so closed - but they're open again now. Perhaps it was just "sticking" for some reason. I might go see if there are any companies that service these types of lenses or indeed, if Sigma do it. Would be worth a few quid just for it to be checked over.

Its weird, I've never had it happen before and the other lenses I have all get used a LOT more than this one so was surprised that it had gone the way it had considering how much use. I was almost tempted to open it up and take it apart - thinking if its broken, I'll have to replace it anyway and if I can fix it, then I've learned something about how lenses work but I guess the I frightened the lens into working, know it was going to be butchered by me - Im not the most graceful person when fiddling with small mechanical parts lol.

Thanks for the time you guys put in to reply though - most appreciated. I'll go crawl into my cave now and hibernate for another 6 months lol. No, I'll be putting some extra time into TP, I've been quite busy, stayed off FB as well as much as I can and got some quality time back with the family as well as some additional time on other projects that I am working on right now.

Thanks again (y)
 
Carlh said:
Thats weird. I just went to take another look at the lens at its opened wide again (the blades aren't closed).

Before today, I took the lens off while the camera was on, with F2.8 showing on the back-display of the 6d and replaced it back on, nothing was changed.

Basically looking through the viewfinder, it was almost pitch dark because of the aperture blades being so closed - but they're open again now. Perhaps it was just "sticking" for some reason. I might go see if there are any companies that service these types of lenses or indeed, if Sigma do it. Would be worth a few quid just for it to be checked over.

Its weird, I've never had it happen before and the other lenses I have all get used a LOT more than this one so was surprised that it had gone the way it had considering how much use. I was almost tempted to open it up and take it apart - thinking if its broken, I'll have to replace it anyway and if I can fix it, then I've learned something about how lenses work but I guess the I frightened the lens into working, know it was going to be butchered by me - Im not the most graceful person when fiddling with small mechanical parts lol.

Thanks for the time you guys put in to reply though - most appreciated. I'll go crawl into my cave now and hibernate for another 6 months lol. No, I'll be putting some extra time into TP, I've been quite busy, stayed off FB as well as much as I can and got some quality time back with the family as well as some additional time on other projects that I am working on right now.

Thanks again (y)
Click to expand...


Hi Carl

Were in your shoes I would "exercise" the lens, put it on the camera set it at f22 and fire away a few dozen shots........this is with the aim of making sure the lubricant that is there is well distributed and the whole diaphragm mechanism is cycled fully.

Obviously this will not 'work' for a situation of impending failure but at least it might make a/the fault more obvious should you send it in for fixing ?
 
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