How To Repair Sigma Zoom Lens

Introduction

My favorite super-wide lens did not survive a 5 human foot drop onto a physical flooring. (Nor did my camera, just that'due south another story.) This repair guide will show how to tear downward the lens and repair a major structural component. It volition also go deeper to show the zoom and focus mechanisms.

A word of alert about disassembling the autofocus machinery - don't do it unless you A) really, really take to or B) are insatiably curious. Nearly of the repair guides out there normally end in the phrase "but my autofocus isn't working." Personally, I haven't figured out the hole-and-corner to putting these suckers back together. The all-time I could do with mine is become information technology "kind of working". And then, take that to heart, and let's become to it!

Fantastic little APS-C format lens. Note the big bulbous front element.

Fantastic little APS-C format lens. Note the big bulbous forepart chemical element.

There are a guhzillion tiny screws and pieces in this lens. Get a bunch of ziplock baggies to hold each piece and its screws. Trust me on this.

There are a guhzillion tiny screws and pieces in this lens. Become a bunch of ziplock baggies to hold each slice and its screws. Trust me on this.

Remove the four screws holding the black eye slice. There'due south i screw that sticks out a chip - no need to remove that one.
Remove the cardinal black piece. The camera connector plate volition hang loose for a while.

Remove the iv screws property the mounting plate. Elevator off the mounting plate. (Photo shows inner components in place.)
Remove the four spacer rings below the mounting plate. Exist careful not to bend the contumely rings.

Unscrew the two screws property the focus switch plate. The plate should just fall off.

At that place is one screw securing the elevation encompass. Remove the screw and lift off the cover.

The ribbon cables are inserted into like shooting fish in a barrel click connectors. Carefully pull out the retaining sliders and remove the cables.
Remove the one screw holding the autofocus switch. Remove the switch. Information technology's sticky on the back so information technology will take a flake of levering.

Unscrew the 2 screws securing the excursion board. Remove the board.

Remove the safety grip around the zoom ring.

Peel off the copper tape covering the zoom encoder fingers.
Unscrew and remove the zoom encoder fingers. Be careful - these fingers are very delicate.

Remove the screw deep within the brass zoom finish. Grab the zoom finish with tweezers. Jerk it until it comes free.
If you want, or need to, you can remove the zoom ring. Rotate it and gently pull up until it pops off. Leave it in place if you can to prevent damage to the encoder.

In case you're interested (and acknowledge information technology, you are) there is no screw underneath the pretty SIGMA DG sticker.

Remove the three screws around the outer ring. Lift off the zoom ring associates. Don't snag the ribbon cables.

If the lens takes a difficult hit, it is this zoom assembly that will probably break . In my case a couple of the support studs snapped off.
Glue any cleaved pieces with strongest epoxy glue you tin find. Superglue is probably not a good option considering it won't handle any lateral knocks.
Be conscientious not to get gum where you don't want it. Use tape to keep the gum in place.
Put some weight on the associates while the gum dries so that the repaired studs stay in position. If they are raised, even slightly, the lens alignment will exist off.

Attempt not to get mucilage down the outer side of the support stud. Backlog mucilage will interfere with reassembly later. If glue does go in the wrong place, carefully grind it downwards with a dremel tool once it hardens.

The next step volition costless the lens unit from the focus barrel. If you don't properly support that big, bulbous, expensive front element it volition fall clunk to the table superlative.
Take a blob of plasticine or playdough about the size of a tangerine. Stick it into a baggie (baggies are your friend!) and mold it into a flattened ball with a paring most the size and shape of that big front chemical element.
Take a clean lens fabric and lay it on pinnacle of the baggie. Nestle your lens into the dent. The plasticine should support the unabridged lens off the table. I.eastward., the lens hood should not be touching the tabular array.

The screws holding these pieces together are in there very tightly. Make certain your screwdriver has sufficient 'bite' or y'all will strip the head (and and so you're in deep problem). You may also have to push down quite a scrap to get the screws to turn. Discover a friend to hold the lens steady while you do this.
Unscrew the five screws around the tiptop of the light gray band. This volition complimentary the lens unit from the focus barrel.
Put a tab of masking tape, or an elastic ring, on the lens hood (not the focus ring). Marking the location of the ribbon cable. This will save you much grief during reassembly.

Danger! Your autofocus may never work once again if you proceed past this point.
Remove the four screws from the inner base of the zoom ring housing. They will require some torque to become them out. Make sure your screwdriver has enough 'bite' and button downwardly while turning. Go your friend back in to hold the barrel steady.
The housing volition effort to bound upward; unscrew the screws evenly and apply some downward force per unit area on the housing as you remove the screws.

Remove all of the rings up to, merely not including, the i with the F stop labels. It won't come up off - don't force it.
With a small tipped tool, remove two of the three impossibly small plastic tabs from the barrel. Don't remove the ane behind the F-stop label - it'south a right pain to put dorsum in.
Remove the remaining rings including the brass clutch plates.

Remove the rubber focus grip. The focus grip is not interchangeable with the zoom grip. The focus grip has slightly effectively "fingers".
Remove the three screws and their bearings from the focus ring.
Pull the focus band directly upwards to remove.

This teardown doesn't go whatever further. Become alee and disassemble the lens unit if you lot dare.
Reassembly is catchy; the remaining steps will aid you put it dorsum together again.

Drop on the focus ring and supercede the screws and bearings. Flip the bearing rings and so that they nestle into the screws.
Skid on the rubber focus grip. Use the one with the finer ribs.

The order of associates, from bottom to meridian is:
Steel/plastic, brass clutch plates, focus indicator, black plastic, thin prophylactic, rotor (thick black), stator (funky brass matter with a ribbon cablevision), fiber, split up steel, cobweb, steel (no dissever), thick brass, thin brass, spring.

Insert the ring that is steel on i side and black plastic on the other. Plastic side goes down. Appoint the tabs into the focus band.
Drib in the clutch plates and appoint the inner tabs into the key barrel. Be careful not to lose the tiny brawl bearings in the plates.

Drop on the focus indicator ring. There are shallow indents on the lesser that engage the tabs on the bearing plates. (Shown here in an assembled state.)
The ring can go on two means. Brand sure the numbers are on the aforementioned side as that mark you made earlier.

Driblet on the blackness plastic band and rubber ring . The rubber band should nestle nicely into the plastic ring.
The focus label should exist on the same side as the mark on the lens hood.
The rotor is the moving part of the ultrasonic wave motor. Information technology'southward the metal ring that'southward black on ane side, shiny on the other. Driblet it on with the shiny side down. (Sorry, no motion-picture show.)

The stator is the stock-still half of the ultrasonic wave motor.
Insert the impossibly small plastic tabs into the main barrel. These agree the stator in the correct position.
Driblet on the stator with the wire pointing upward. There are indents on the inside that line upwardly with the impossibly pocket-sized plastic tabs.
The stator will go on 3 means. Make certain the ribbon cable aligns with the marking you made earlier.

Drop on the remaining rings in this order:
Fiber ring, divide metal band (it has a little tab that engages into the butt), the other fiber ring, solid metal ring, brass rings, spring. (Apologies for the crap picture.)

Drop on the metal zoom barrel. Secure with the four screws.

Drib the focus assembly onto the primary lens module. Exist conscientious with the ribbon cables.
Align the 5 screw holes. Secure with screws.

Drop on the zoom assembly. Carefully thread the focus encoder cablevision through the slot.
Marshal the screw holes and secure.

Rotate the zoom band until the oval hole lines up with its mate on the lens module. Insert contumely pin and secure with a screw.
Reattach the zoom encoder fingers and copper tape.
Replace the rubber zoom grip.

Reinstall the circuit board with the two screws.
Replace the zoom switch.
Insert all ribbon cables and firmly (but carefully) click the connectors in to identify.
Insert the camera connector cable and click the connector.

Drop on the elevation cover and align with the screw holes. The big side fits over the zoom switch.
Secure with one screw. The spiral hole is slightly deeper than the other holes.

Make sure the interior and exterior zoom switches are in the same position. They must line up when you lot replace the cover.
Replace the zoom switch embrace and secure with two screws.

Replace the spacer rings. The brass rings go on the bottom, the thickest black ring is on acme. The rings fit onto a tab that keeps them aligned. Make sure the holes line upward with the screw holes in assembly below.
Driblet on the mounting plate. The long leg goes inside the lens and into a hole in the primal lens associates; it's easy to see.
Secure the mounting plate with iv screws. The shorter spiral is directly reverse the reddish dot.

Attach the photographic camera connector plate with 2 screws. These screws accept a finer thread than the others.
Insert the blackness center piece. Secure with the remaining two coarse-thread screws.

Conclusion

Mount onto a photographic camera and you lot're proficient to go!