Introduction
Symptom: Badly exposed pictures. Depending on the way the aperture is stuck, you'll see mostly all pictures over- or underexposed, regardless of manual aperture settings. Autofocus also doesn't find correct settings.
Tools Required
- ? Phillips #00 Screwdriver (1)
Step 1: First Check of Aperture Moving
Move the lever back and forth and look through the lens. The aperture on a good lens should open and close and spring back into position.
Step 2
Remove the 3 little black screws [circled] and the one on the side [arrow ➡️].
Remove the two black screws holding the contact plate in place. Be careful: lift up the contact plate slowly. Underneath the contact plate sits a tiny spring. The spring sits in a hole pressing against the contact plate from below.
Visual Description: Two images show the lens mount. The left image highlights screws to be removed. The right image shows the contact plate removed, revealing a small spring.
Step 3: Remove the Inner Tube
Gently take out the inner tube. Take care of the contact plate, as it is connected with fine wires to the optical parts and cannot be removed.
Visual Description: An image shows a hand carefully removing the inner tube of the camera lens.
Step 4
Extract the lens to its full length (zoom in to 300mm) and look at the inside for the aperture lever. In the image, it correctly grips the lower aperture lever. If there is a problem, the two parts do not line up and connect to each other.
You can try to put it back in place right from this point. Use some tweezers or a plastic spudge: the upper part can gently be bent to snap back in place.
In this case, another problem was noticed: the lever would not move with ease and seemed to get stuck and stop sometimes. It was time to remove the metal ring.
Visual Description: A close-up image of the lens interior shows the aperture lever mechanism, with a red arrow pointing to the lever.
Step 5: Remove the Metal Ring
Unscrew the 4 screws and take off the metal ring. Attached to the metal ring is the aperture-moving lever, so you need to slide it off a long way.
The lever has a small spring attached to the metal ring: keep both parts together to save the spring.
A retaining ring (indicated by an arrow) was found to be out of place; it did not belong there but had fallen out from the just-removed metal ring.
Visual Description: Three images illustrate the disassembly. The first shows screws on the lens mount. The second shows the metal ring with the aperture lever and spring. The third shows these components together.
Step 6: Reattach Retaining Ring to Metal Ring
The problem was identified as the retaining ring having snapped off the metal ring, allowing the aperture lever too much room to move and disconnect from the lower aperture lever.
Put the aperture lever (see left arrow ➡️) and the retaining ring back into the metal ring as shown in the picture. Connect the spring (see center arrow ➡️) if it was disconnected.
The lever was bent slightly to improve its grip on its mating part.
In the upper left part of the first picture, the auto-focus pin is visible; this needs to be aligned in the lens body during re-assembly.
There are three metal rings on the lens body: do not mix them up. The picture shows the correct order.
Visual Description: Three images illustrate the reassembly. The first shows the metal ring with the aperture lever and retaining ring, with arrows pointing to key areas. The second shows the spring being reconnected. The third displays the three metal rings that are part of the lens body.
Step 7: Re-assembly
This can become a little tricky. It is best to extract the lens to its full length.
Put the metal ring back and align the auto-focus pin with the gear wheel in the lens body. Slightly turn it with a screwdriver until it fits into the hole of the gear wheel.
At the same time, try to align the two aperture levers so that they are connected.
Visual Description: An image shows the lens body with the metal ring being re-attached, highlighting the auto-focus pin alignment.
Step 8
Put the remaining parts back. Always tighten the screws very loosely at first and continue tightening them in a starway fashion (opposite sides).
Visual Description: An image shows the lens mount with screws being tightened in a star pattern.
Step 9: Bonus Pictures
In case you wish to disassemble further, here are some detail shots of what to expect. These are not necessary for the aperture fix.
Removing the 4 black screws allows you to remove the big optical tube. Just slide it out carefully.
You can see some decoder contacts: clean them and look for eventual problems here.
The optical part could not be removed from the housing. Hopefully, iFixit members can provide further insight.
Visual Description: Three detail shots of lens components are provided, showing internal mechanisms and contacts.
German Instruction: "Arbeite die Schritte in umgekehrter Reihenfolge ab, um dein Gerät wieder zusammenzubauen." translates to "Work through the steps in reverse order to reassemble your device."
