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08-09-2009, 06:42 PM   #1
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How clean the insides of a Sigma 17-70 -

It seems Sigma 17-70mm have a fair reputation of getting dusty between the front group and middle focusing groups; and it can get really dirty fast in the wrong places. For some users it has been a problem. You can have it cleaned or save yourself a lot of money for what is a very easy job. However I have not found as many complaints as some non Canon L zooms, seems they get dusty in days (some models).

Credit goes to Zaldidun at dpr PentaxSLR forums for showing me the ring tools.

After about 9 months of occasional use mainly outdoors my Sigma 17-70mm had too much dust for my taste. I had it cleaned and adjusted before the warranty ended but in two months it got more dust oh yes anal I know. The dust does not hurt IQ at all so if you don't feel good about taking your lens apart don't

1) You need a tool to grip the purely decorative ring around the lens that hides the screws. Take a look at the tools at the link I provided. I made my own homemade tool. Some have no luck, but remember my lens has been taken apart by Sigma before so its probably not as tight as lens never touched. The tools don't cost a lot. I don't know the right size to order, they have a universal one for $18, thats suppose to fit all, does it fit the Sigma (?).

Turn the ring toward the left (counter clockwise) to remove it. Below it is about 6 or 8 (I forgot) little screws, you will need a special Philip's screw driver made for small parts. Those screws hold the hole top piece down when you take them out you can just lift off the elements and plastic top all in one piece, there are spacers so be careful, I mean don't forget to put the spacer back on, if you do you probably should not be doing this anyways .

Gently blow out the chamber and glass, set it back on the same way it came off, put the screws back in, spin the ring back down, done. I can now clean my Sigma 17-70mm in less than 10 minuets. Its a very easy job, and you can't as far as I can tell hurt calibration. But do this at your own risk.

I would strongly advice taking the time to get the right tool to grip the ring. You don't want to touch the glass when you spin the ring. Look at the tools in the catalog. If you can make something at home great (as I did, but mine was loosened before during warranty!). This is the hardest part, the rest is easy.

There are lots of Sigma 17-70mm owners I know I read one here where their dads Sigma got full of pollen, well now you know how to get it out and never have to worry again. Hope this helps someone.

I have posted the place to get the tool they sell a black ring set for most sizes that are hollow so they don't touch the glass, this one I may get myself. The other single ones are cheaper but you have to hallow them out yourself if you don't want them touching your glass, sound harder than the job itself .

The two tools you can order, I made my own. But, my was already removed before (get the right tool ).


https://www.micro-tools.com/store/mainframe2.aspx









And a Pic with my clean Sigma of a Pentax lens. Does it take better pics? Nope, does it take worse pics? Nope, but I love having a spotless lens And I have read some cases that were the dust was so bad it could affect IQ. But again you don't have to, and if your nervous don't do it and just enjoy your lens.

08-09-2009, 07:20 PM   #2
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So you managed to open up the front element, but how do you clean the internal and rear elements? Using a blower is just risking blowing more dust internally. Anyway haven't had a dust issue with my Sigma 17-70mm. What home made tool did you use?
08-09-2009, 09:35 PM   #3
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QuoteOriginally posted by creampuff Quote
So you managed to open up the front element, but how do you clean the internal and rear elements? Using a blower is just risking blowing more dust internally. Anyway haven't had a dust issue with my Sigma 17-70mm. What home made tool did you use?

No risk or very low risk of getting dust inside, if you see it apart in real life. The dust was stuck to the front elements so it was not even near the lens when I blew it. If your careful there is little to no chance of blowing dust down into the other sealed elements. If your worried you can use one of those stick pens or something.

As far as the other elements the dust in them is rarely visible. We are talking about cleaning not for IQ but because some of us our anal and don't like looking at it. The only other place you may see a very tiny speck of dust is in the rear. The other elements are sealed. The largest air chamber and where the lens clearly lets you see the dust is of course up front. Only if you have a bad dust problem, fungus, or water damage would you take out the other elements. This cure of mine for the Sigma 17-70mm is strictly for the visible I hate looking at it dust under the front elements

My gizmo was a 62mm white balance cap. The elcheapo type from eBay it fit the Sigmas ring perfect so I cut out the white inner part and was left with a black plastic ring, but it could not grab on to it (the Sigma ring). I used a cut rubber band so it lay-ed on the rubber I pushed down and turned. It came off fairly easy probably because it just came back from being cleaned a couple months ago and was opened then. As well as adjusted. There is little harm you can do if you just don't touch the glass, put the front assembly back in the way it came out, and not a bad pointer to use some caution in removing the dust and NOT just blow it all around.
08-09-2009, 11:35 PM   #4
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i would be interested to know if anyone finds out the right sized tool to fit the sigma 17-70, i sort of grazed the metal trying to open mine, (turned a little way then stopped) but it won't be noticeable if i paint the silver graze black.. the glass is still perfect though untouched but i still am yet to get it open, i have some fungis inside i would love to remove

08-10-2009, 12:11 AM   #5
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QuoteOriginally posted by happyant Quote
i would be interested to know if anyone finds out the right sized tool to fit the sigma 17-70, i sort of grazed the metal trying to open mine, (turned a little way then stopped) but it won't be noticeable if i paint the silver graze black.. the glass is still perfect though untouched but i still am yet to get it open, i have some fungis inside i would love to remove

I want to order the tool as well just because its the right way and its not too much $$. My best guess going by the fact I used a 62mm WB lens cap is that it is the #62 and #63 tools. Which is the largest on the black lens ring tool set for $18.00. But the others are cheaper and it says the rubber grabs better than the black rubber. However you may have to hollow the inside of the tool out a bit. I do notice the ring around the Sigma is raised then drops to where the filter is screwed on , take a look, but I don't think its high enough to clear the lens; its real close though, it may work as is (the tool).

I also measured it and a tool 63mm would fit perfect. Don't know but I think I am going to order the tool at that size. If you like you can wait and see if it works for me.

BTW use a black permament marker for your ring,

Last edited by jamesm007; 08-10-2009 at 12:19 AM.
08-10-2009, 01:50 PM   #6
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nice. this reminds me of cleaning my old tokina 50-250.

one question. wouldn't this procedure alter the front element's alignment?
in short, would it not affect the focusing ?

tnx
08-10-2009, 08:32 PM   #7
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QuoteOriginally posted by opiedog Quote
nice. this reminds me of cleaning my old tokina 50-250.

one question. wouldn't this procedure alter the front element's alignment?
in short, would it not affect the focusing ?

tnx
IMO no, in my experience with this lens front group, no. If you have doubts don't do it. If you have a problem with dust, fungus, water stains, that does affect IQ and the benefits out weigh the risk go ahead. But don't do it unless your good with your hands, and need to, and or want to. But at your own risk

03-13-2016, 05:06 PM   #8
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QuoteOriginally posted by jamesm007 Quote
It seems Sigma 17-70mm have a fair reputation of getting dusty between the front group and middle focusing groups; and it can get really dirty fast in the wrong places. For some users it has been a problem. You can have it cleaned or save yourself a lot of money for what is a very easy job. However I have not found as many complaints as some non Canon L zooms, seems they get dusty in days (some models).

Credit goes to Zaldidun at dpr PentaxSLR forums for showing me the ring tools.

After about 9 months of occasional use mainly outdoors my Sigma 17-70mm had too much dust for my taste. I had it cleaned and adjusted before the warranty ended but in two months it got more dust oh yes anal I know. The dust does not hurt IQ at all so if you don't feel good about taking your lens apart don't

1) You need a tool to grip the purely decorative ring around the lens that hides the screws. Take a look at the tools at the link I provided. I made my own homemade tool. Some have no luck, but remember my lens has been taken apart by Sigma before so its probably not as tight as lens never touched. The tools don't cost a lot. I don't know the right size to order, they have a universal one for $18, thats suppose to fit all, does it fit the Sigma (?).

Turn the ring toward the left (counter clockwise) to remove it. Below it is about 6 or 8 (I forgot) little screws, you will need a special Philip's screw driver made for small parts. Those screws hold the hole top piece down when you take them out you can just lift off the elements and plastic top all in one piece, there are spacers so be careful, I mean don't forget to put the spacer back on, if you do you probably should not be doing this anyways .

Gently blow out the chamber and glass, set it back on the same way it came off, put the screws back in, spin the ring back down, done. I can now clean my Sigma 17-70mm in less than 10 minuets. Its a very easy job, and you can't as far as I can tell hurt calibration. But do this at your own risk.

I would strongly advice taking the time to get the right tool to grip the ring. You don't want to touch the glass when you spin the ring. Look at the tools in the catalog. If you can make something at home great (as I did, but mine was loosened before during warranty!). This is the hardest part, the rest is easy.

There are lots of Sigma 17-70mm owners I know I read one here where their dads Sigma got full of pollen, well now you know how to get it out and never have to worry again. Hope this helps someone.

I have posted the place to get the tool they sell a black ring set for most sizes that are hollow so they don't touch the glass, this one I may get myself. The other single ones are cheaper but you have to hallow them out yourself if you don't want them touching your glass, sound harder than the job itself .

The two tools you can order, I made my own. But, my was already removed before (get the right tool ).


https://www.micro-tools.com/store/mainframe2.aspx









And a Pic with my clean Sigma of a Pentax lens. Does it take better pics? Nope, does it take worse pics? Nope, but I love having a spotless lens And I have read some cases that were the dust was so bad it could affect IQ. But again you don't have to, and if your nervous don't do it and just enjoy your lens.
As the OP I want to say don't try this. Its not worth the risk of cosmetic or even worse damage. I have learned a lot over the years here. Thanks to all. I know dust is only an issue if its on your sensor. Otherwise forget about it. Also as you mature in this hobby you truly do forget about dust. Even if I see it I don't care.

Just say no!
08-04-2017, 07:54 AM - 1 Like   #9
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No need to order the tool...
...if you're the average italian.
Just use a 6-cups coffee-machine replacement ring. It works perfectly.
Place it on the objective, then turn it upside-down, and turn it pushing gently on a clean surface: the objective ring will come out without problems.
There are 6 small screws, and once you remove the main lens you'll see three metal rings: remember (or photograph, or note down) their precise position, in relation to the lens and objective, otherwise you'll sweat to get them back in place.
Dust is gone, speckles in the sky also!
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04-05-2018, 05:58 PM   #10
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QuoteOriginally posted by leodp Quote

Place it on the objective, then turn it upside-down, and turn it pushing gently on a clean surface: the objective ring will come out without problems.
Are you used your bare hand to turn and push the ring?
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