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Archive 2013 · So I disassembled my first lens...

  
 
TurbosLS1ta
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p.1 #1 · p.1 #1 · So I disassembled my first lens...


About a year ago I purchased Sigma 24-70 2.8 off ebay. The price was almost too good to be true, so I pounded the seller with questions, and he assured me it was in great shape. Well when I got it, the front barrel was loose, and it had an obvious mark from being dropped right next to the objective lens, which wasnt shown in the photos due to some clever photoshopping. The box it came it was in good condition so I know UPS didnt damage it. Anyways it still took decent photos. At 70mm it was pretty soft and had some distortion from the lenses being out of alignment. So last night I finally decided to tackle trying to fix it. The disassembly was pretty easy, my biggest fear was trying not to tear the power ribbons to the focusing motor. I found the problem to be broken plastic spacers connecting the the front barrel to the body. What got my attention was I was only able to find one piece of three of the broken washers inside the body, which tells me maybe the previous owner tried fixing it himself. Anyways, the closest to these washers I could find locally were some #4 nuts, which I had to file to a round shape but worked perfectly. Assembly was pretty easy and straight forward. Putting the power ribbons back into their connectors was a PITA for someone with gorrila hands. The only issue I had is some dust that got into the lenses. I did my best to blow everything out as I was assembling it, but it wasnt enough. I dont think it will affect IQ, but my ADD is getting to me so I'll probably take it apart again to get them all out.
Since I only paid $300 for it, and a repair probably would have cost just as much, I figured it was a good learning experience. Definitley wasnt as bad as I thought it would be.



May 25, 2013 at 09:35 AM
Turbohamster
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p.1 #2 · p.1 #2 · So I disassembled my first lens...


Glad u managed to fix it!

But surely if it wasn't as described you could of sent it back



May 25, 2013 at 09:46 AM
scalesusa
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p.1 #3 · p.1 #3 · So I disassembled my first lens...


The plastic spacers are a common failure point in many lenses. You should be able to get replacements at any camera repair shop or from the manufacturer. They are like a fuse, cheap and break to prevent damage of more expensive items.


May 25, 2013 at 10:19 AM
TurbosLS1ta
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p.1 #4 · p.1 #4 · So I disassembled my first lens...


I tried to send it back. The seller cut off all communication with me after the sale. And for those of us who have had these issues in the past, we all know how helpful ebay and Paypal really are. Since it still functioned somewhat properly, I just decided to eat the loss.


May 25, 2013 at 11:21 AM
RCicala
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p.1 #5 · p.1 #5 · So I disassembled my first lens...


Be careful - - those broken eBay lenses are gateway lenses. Look what's happened to me.


May 25, 2013 at 11:34 AM
corndog
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p.1 #6 · p.1 #6 · So I disassembled my first lens...





May 25, 2013 at 11:46 AM
EB-1
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p.1 #7 · p.1 #7 · So I disassembled my first lens...


I've disassembled a fair number of lenses over the years. So far I only put one back together.

EBH



May 25, 2013 at 12:47 PM
TurbosLS1ta
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p.1 #8 · p.1 #8 · So I disassembled my first lens...


I may disassemble it tonight again to clean the elements, so ill try to do a full write up with pictures. I was more focused on not screwing it up the first go around.


May 25, 2013 at 12:56 PM
lowa2
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p.1 #9 · p.1 #9 · So I disassembled my first lens...


corndog wrote:
http://www.worldaffairsboard.com/attachments/sports-bar/29676d1343478806-olympics-2012-201250d1224730070-fuse-diagram-thread-useless-without-pictures.jpg


If he disassembles it again to get the dust out, maybe he can get some pics :-)

That picture is hilarious.



May 25, 2013 at 03:06 PM
scalesusa
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p.1 #10 · p.1 #10 · So I disassembled my first lens...


TurbosLS1ta wrote:
I tried to send it back. The seller cut off all communication with me after the sale. And for those of us who have had these issues in the past, we all know how helpful ebay and Paypal really are. Since it still functioned somewhat properly, I just decided to eat the loss.


I've found that a report of not as advertised gets a automatic freeze of the sellers paypal funds, and ebay will refund your payment as well.

But ... You need to report the issue in a reasonable amount of time, like a couple of weeks or less. Beyond that, it becomes more likely that its something that failed after you received the lens.



May 25, 2013 at 06:19 PM
TurbosLS1ta
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p.1 #11 · p.1 #11 · So I disassembled my first lens...


Ok, so here is probably the most in depth write up Ive ever done, so bear with me.
Some tools you will want are a small pick, small flat blade screw driver, PZ0 (or sunglass kit) philips screwdriver, needle nose pliers, loctite, flashlight (or headlamp, or a very well lit room), can of compressed air.

Here is the culprit lens, a Sigma 24-70 f/2.8 EX DG. I cant imagine the majority of lenses being much dissimilar in the process, but they may be, so this is meant to serve as a general guide. Once your eyes have fallen upon this write-up, I am no longer responsible for your screw-ups or voided warranty, etc whilst you commence tearing down your own lens.


I figure what happened is the previous owner dropped in (just missing the objective lens, luckily) which shatter the plastic washers in the zoom tracks (forgive my lack of a technical term) inside the camera. The front barrel was loose from the rest of the body, but surprisingly took sharp pictures up until the 70mm range.


So the first step is to remove the four (4) stainless screws from the mounting plate.


BEFORE you remove the mounting plate, you must disconnect the power ribbon connected to the circuit board underneath. BE EXTREMELY CAREFUL, as these ribbons tear easily. Never force or pull them hard.


To disconnect the ribbon, you will need a small flat blade screwdriver or pick to push the black tabs open. This one is tricky as you will have to be careful when holding the mounting plate and trying to disconnect the ribbon at the same time. As you can see, there is not alot of room to do it. The red arrows indicate the tabs to press, and the blue arrow indicates the direction to push them to unlock them. This pic shows the connector unlocked.


Once you have the mounting plate removed, you will have to remove the brass spacers. There are several of them in various thicknesses. Im not sure if their order is important, however notice the pinhole orientation 180* from the power ribbon connector.


When the spacers are removed, you will see three (3) counter sunk screws. Remove them.


Once the screws are removed, I advise moving the focus switch to the Manual (M) position. This moves the switch pawl up, making it easier to slide off the gear during removing and re-installing the focus switch ring.


Once the focus switch ring is off, you have better access to the circuit board. Remove all the ribbons from their connectors the same way you removed the first ribbon. Once they are out, remove the one screw holding the circuit board to the body (be careful, its a tiny screw).


The circuit board is connected to the focus motor via a red and black wire, so just let it dangle to the side while you remove the three screws holding the focus motor/gearbox on.



Remove the focus gear and spring, noticing the gear orientation.


Next remove the two screws holding the ribbon to the body. Place a finger where the blue arrow indicates, as removing the screw can twist the ribbon, possibly tearing it.


Remove the rubber grip band from the zoom ring. Under it you will notice a single screw. Remove it, and be careful as it can fall into the body.


Once the zoom ring screw is removed, look right inside the zoom ring and you will notice it is indexed to the internal body. DO NOT ROTATE THE ZOOM RING MORE THAN 90*! Doing so will damage the electronic "fingers" inside the ring used to locate what zoom range the lens is at. When the ring is indexed properly, it will come off.


The "fingers" ride along this ribbon, so the camera can figure out what focus/zoom range the lens is at.


Once the zoom ring is off, remove the three screws shown to disconnect the internal elements from the outer body.


Once those screws are removed, the outer body should just slide right off. In the case of my lens, the zoom ring tab had come loose from the internal element, making it difficult to remove. If this happens, dont force it- just wiggle and work it a little and it will come.


Viola


These are the screws that had the plastic washers that were broken, causes the loose objective barrel. All I could find locally were some #4 nuts. The fit over the screws perfectly and all I had to do was file the hex down to make the nuts round. Once I can find the proper parts, I will replace them, however I am like most photographers and cant live without my equipment for long.


If you need to disassemble any further than this, then you have some serious problems I may not be able to help with (cracked glass is about it).
Re-assembly is pretty much the exact opposite of disassembly. Again, just be very careful of the ribbons. I was fortunate that the ones in this lens were in good shape, but old, aged lens will have very brittle ribbons. As for the can of compressed air- use it alot during assembly. Dust WILL get into the lens while it is apart. If not, any dust that is already in the lens willc ome out, making your photos even better than before..



May 25, 2013 at 08:44 PM
scalesusa
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p.1 #12 · p.1 #12 · So I disassembled my first lens...


Make sure you use jis type screwdrivers. Some try and use a Phillips, but that can round off the cross recess and make a mess of things.

A spanner wrench is handy for some lenses.

Its a much better experience if you use the right tools.



May 25, 2013 at 10:08 PM
RonR2
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p.1 #13 · p.1 #13 · So I disassembled my first lens...


For the nylon washers look in a good hardware store, not the big box type but the old fashioned "if we ain't got it you don't need it type", they normally have drawers of nuts bolts and washers. Meant to add stores like True Value and Ace are good places to start.


May 26, 2013 at 06:49 AM
schlotz
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p.1 #14 · p.1 #14 · So I disassembled my first lens...


Probably not a good idea to have had coffee prior


May 26, 2013 at 09:08 AM
gfiksel
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p.1 #15 · p.1 #15 · So I disassembled my first lens...


Dust is the least of concerns.
Fat fingerprints - wear latex
Hair and skin scales - wear a hairnet.



May 26, 2013 at 09:19 AM
TurbosLS1ta
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p.1 #16 · p.1 #16 · So I disassembled my first lens...


Latex gloves would be a good idea, but unless you have rat fingers, you wont be able to touch the inner elements unless to completely tear the lens down further. I would also reccomend an anti-static wristband or make sure you drain any static charge since you are working with circuitry.


May 26, 2013 at 10:40 AM
corndog
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p.1 #17 · p.1 #17 · So I disassembled my first lens...


Either way, thanks for showing us the inside of your lens!


May 26, 2013 at 12:00 PM





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