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Repairing a Sigma 70-210 f/2.8

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Osi View Drop Down
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Post Options Post Options   Quote Osi Quote  Post ReplyReply Direct Link To This Post Topic: Repairing a Sigma 70-210 f/2.8
    Posted: 28 May 2021 at 10:58
Haha,what do you know, I'm back to this forum to read up my own advice. I got another similar lens with same haze issue, plus other problems. I forgot the methods I used and ended up making same mistake of dismantling the whole lens. Oh well, at least I've not destroyed the guilty element yet and with this my own guide, I will get to it without scratching or damaging it. This lens is a Sigma autofocus Canon mount 70-210mm f/2.8. Very slow belt-driven autofocus. Aperture driven by gears and 2 gears of 3 broken. The effort I put in these things is just for practice and to up my game; not worth the value of the lens at all
 



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beeton View Drop Down
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Post Options Post Options   Quote beeton Quote  Post ReplyReply Direct Link To This Post Posted: 28 June 2020 at 02:49
I have conquered Mount ZEN. Took much work but I have removed and cleaned the slightly foggy element from my Sigma 70-210 f2.8 Zen

History is written up on the fist page. I was having trouble getting consistent micro-focus correct images as the setting required seemed to jump between +9 and -9. That is a huge range. I found then that there was a little slop in the focus ring and even when focus was on, a slight wiggle of the barrel would throw it off. So, I decided to take the lens apart to see if I had a loose gear or something else causing the play. When taking the lens apart, I removed the front-inner cell, the one with the hazy element, as a group. This was done after removing the front ring from the inside, under the objective. Removing that ring exposes the screws that have to be removed to fully pull out the lens group. This ring is a friction-fit. To remove it, I had to use a plastic cap and a rubber ring (lens grip ring from an old lens) and twist off the ring. Once the screws are out (only the 3 outer have to be removed), the lens group can be pulled out from the back. Once done, you have to remove the retaining ring from the BACK of the metal cell in the same fashion as the front ring but with a smaller cap or insert. You can then pull out the inner cell with the elements. There are 3 elements within- one at front and a doublet at back. To remove the elements itself was a challenge. There is no spanner inset for the front ring or rear. The font had locktite and I had to add a bit of nail polish remover to the gap between the threads top dissolve that (don't get any on the elements). Then, remove the front ring by applying a bit of pressure to the ring face (inside, not top and try to push counter-clockwise. BE CAREFUL not to scratch the element or jab yourself. BEFORE YOU REMOVE THE ELEMENTS, TAKE NOTE OF THEIR ORIENTATION. I put it all back together only to realize I had reversed the front element and had to start over.

Cleaned up the haze and lens works great BUT still that play in focus...will have to be careful on shoots. Took some test images. This is a very nice lens. Sharp and except for some vignetting at 2.8 and a bit of loss in the edges, which almost lenses suffer wide open, very good performer. I will try to post some images.
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 03 June 2020 at 00:48
Originally posted by Osi Osi wrote:

Hi. I have sent a message to the e-mail address you provided, with pictures. They were supposed to be for me only. If I knew I would be sharing them with the world, I'd have done a better job of it. Fun fact: I'm in Nigeria!


Hi Osi .

Here are the photos you sent me , hopefully they may be of use to someone doing a search for them .

sigma lens by Neil Taylor, on Flickr

sigma lens 2 by Neil Taylor, on Flickr
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
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Osi View Drop Down
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Post Options Post Options   Quote Osi Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2020 at 17:29
Originally posted by neilt3 neilt3 wrote:

Hi Osi .
That's a sickner losing your phone with all the images on , I know how valuable they are for reference .
.


My dear brother, if I lost only my phone with disassembled electronics, that's pretty painful; but it was my entire record of uncountable bookmarked pages,apps, settings, maybe over 19,000 images and thousands of video clipses on various subjects - most simply irreplaceable. I last backed up a full year previously. What I could get hardly represented 10% of what I lost. It feels worse than the death of a human being. I was willing to pay more than the value of the phone to get my information back, but when you misplace your phone in Nigeria, my brother, please forget it. The first thing they do is switch it off and throw away the SIM card and you can't contact them again. They're incapable of considering how vital information in a phone can be.

Edited by Osi - 30 May 2020 at 17:32
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Post Options Post Options   Quote Osi Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2020 at 17:15
Hi. I have sent a message to the e-mail address you provided, with pictures. They were supposed to be for me only. If I knew I would be sharing them with the world, I'd have done a better job of it. Fun fact: I'm in Nigeria!
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2020 at 16:25
Hi Osi .
That's a sickner losing your phone with all the images on , I know how valuable they are for reference .

I've P.Med you my email address .

When I get chance I'll get them on Flickr and posted here so anyone doing a search can find them .
Hopefully they will be of help to others .
Cheers .
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
 



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Osi View Drop Down
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Post Options Post Options   Quote Osi Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2020 at 15:52
Hi. I did take somebody up on the offer and sent a picture to their e-mail as I recently mentioned. Probably wasn't you then. Please send me your e-mail as a direct message so I can do same. I recently lost a phone containing over 500 pictures of different cameras and lenses under varying stages of disassembly which I use myself. I can regard myself as fairly experienced now and I've always been a competent person (but camera/lens repairs seriously challenged that and I incurred many knocks in the learning process) and I benefitted immensely from online fora like this (still do, hence my appearance here) and I find it fulfilling if I can help others also. I'm just not in sync with the picture policy here. I want to be able to type stuff and click on an attachment tab and upload a picture from my phone. This is what I'm used to. Maybe that would change but for now, I'd rather do it the way I've proposed. We're all in it together (Lol)
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2020 at 14:09
Originally posted by pegelli pegelli wrote:

Originally posted by Osi Osi wrote:

The picture policy of this forum is an Achilles heel

Judging by the amount of pictures posted on this forum on a daily basis it can't be that hard: see here for instructions

Btw, good luck with the lens repairs


As explained in March , it's simple and free to start a Flickr account to post images on here , and other places .

I also offered to put the images on my Flickr site and post them in this thread to help others in the future .
Not been taken up on the offer though . Shame .
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
C & C welcome.
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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 30 May 2020 at 13:53
Originally posted by Osi Osi wrote:

The picture policy of this forum is an Achilles heel

Judging by the amount of pictures posted on this forum on a daily basis it can't be that hard: see here for instructions

Btw, good luck with the lens repairs
You can see the April Foolishness 2021 exhibition here Another great show of the talent we have on Dyxum
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oldglass View Drop Down
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Post Options Post Options   Quote oldglass Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2020 at 20:30
Originally posted by Osi Osi wrote:

I was still waiting for your link to produce a picture to no avail. The picture policy of this forum is an Achilles heel


I uploaded my images to an external hosting service (Imgur). Perhaps the forum software mangled the link for you? Try going to i.imgur(dot)com/waX8gFs.jpg
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Osi View Drop Down
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Post Options Post Options   Quote Osi Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2020 at 20:21
Originally posted by oldglass oldglass wrote:

Wow, thanks for the quick reply, Osi!

Just to confirm, the ring I should be twisting is the ring pictured here around which I've placed the rubber band? I've tried twisting it a few times and just want to be sure before I tire myself out too much!

Thankfully, someone else has chimed in to validate. I was still waiting for your link to produce a picture to no avail. The picture policy of this forum is an Achilles heel
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Post Options Post Options   Quote beeton Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2020 at 20:13
Yes, that's the one. It is difficult at first as when you tighten you grip, you may be squeezing it out of round. Try from a few angles. Normal direction (left).

When you get it off, the front barrel will come off (with the af version). The front element AND barrel underneath are held in place with tape. Do NOT take that tape off without first marking the front to rear sections or you will have difficulty aligning them back on.

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Post Options Post Options   Quote oldglass Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2020 at 19:52
Wow, thanks for the quick reply, Osi!

Just to confirm, the ring I should be twisting is the ring pictured here around which I've placed the rubber band? I've tried twisting it a few times and just want to be sure before I tire myself out too much!
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Osi View Drop Down
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Post Options Post Options   Quote Osi Quote  Post ReplyReply Direct Link To This Post Posted: 29 May 2020 at 18:24
Hi everyone. I did send the only picture I took of the completely disassembled lens to someone on here by e-mail but he said he was no longer going to attempt any further to work on it since his wasn't that bad. For the last poster's situation: indeed the focusing lens group is in the very front part. To access it, you will observe that the entire front section has a wider diameter than the focusing grip part. Take your hands from the very front of the lens all the way to the end of that part with same diameter. At the end of it, before the focusing grip is a ring deceptively placed there to lock the front barrel in place. Looking from the back of the lens, turn the ring in the normal anticlockwise direction and voila, the front barrel comes off going further forward. The very first front glass is attached to the rest of the lens by just a black tape! I'm sure you can figure out the rest or else my response will get too long and unwieldy. Please let me know how it went
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