Sigmatel 135mm F1.8 YS Multi (How can i Open the Lens to clear it?)

Sniggi · 12-03-2018, 01:11 AM

Hello,
recently i bought a well worn sigmatel 135mm F1.8. The Lens has a lot of fungus in it and i was trying to Clean it but i couldnt find out how to open The Lens, to clean The glass elements. Is there a was to open it?

noblepa · 12-03-2018, 12:18 PM

I'm not familiar with that particular lens, but many lenses have a threaded retaining ring at the front of the lens. This ring usually has the name, focal length, aperture size and serial number engraved on it.

I've read of a trick to unscrew the ring, in which a short piece of PVC pipe of the appropriate diameter, used with a rubber pad (sometimes used as a bottle opener) will give you enough grip to turn the ring and unscrew it.

Alternatively, you could drill two small holes, opposite each other, into the ring and use an adjustable spanner wrench.

stevebrot · 12-03-2018, 06:08 PM

Welcome to the Pentax Forums!

Is this your lens?

Sigmatel 135mm F1.8 "Multi Scalematic" Y/S Lens Reviews - Sigma Lenses - Pentax Lens Review Database

It so, it might be worth getting a bid from a professional for the cleaning. There are quirks to opening every lens and most designs feature traps for the unwary. Taking a lens apart requires special tools, excellent dexterity, good eyesight, and patience. It also helps to have a description of what to expect since many lenses have a mixture of left and right-hand thread and some non-intuitive actions to get to the optical assemblies. In regards to special tools, if a Japanese camera or lens has a cross-head screw, it is most likely JIS head and not Philips-head. Using a Philips screwdriver carries the risk of stripping the head with few options to extract and salvage.

I buy most of my camera repair tools from Micro-Tools. Their EU Web site is at:

Micro-Tools Europe Tools | Miniature Tools for Camera and Watch Repair

Good luck.

Steve

P.S. Given that your lens is unusual and sort of rare, I would avoid drilling holes, if at all possible.

**.a.t.** · 12-03-2018, 08:28 PM - **1 Like**

Originally posted by Sniggi

Hello,
recently i bought a well worn sigmatel 135mm F1.8. The Lens has a lot of fungus in it and i was trying to Clean it but i couldnt find out how to open The Lens, to clean The glass elements. Is there a was to open it?

Hi Sniggi,

If you already have some experience and the right tools, this Sigmatel is relatively easy to open.

To get inside the front end, turn the focus ring to the minimum focus distance. Then you should see a small slot head screw above the focus ring. Loosen the screw just a couple turns - it doesn't need to be removed. (If the screw comes out, it'll be easy to lose and difficult to get back in place!)
With that screw loosened, the front part of the lens can now be unscrewed counterclockwise. Then you'll have access to the front elements.

With the top piece / retainer off, the front element should come out easily. Next, there's a spacer ring to lift out. And then a cemented triplet should also slide out easily.

There are also two elements behind the iris. When the iris is wide open, I believe the next element will also fall forward and out. And to get the rear element out, you'll need a spanner wrench or similar tool.

To remove the rear element, focus the lens to infinity and remove the mount adapter. Depending on which adapter you have on your lens, it might simply spin off, or it may require removing some screws first.
When the adapter is off, you'll have easier access to the retaining ring so it can be removed with a spanner.

Here's what my lens looked like when I had it apart for cleaning a few months ago:

In the picture, the second to last element is still inside the lens because I didn't need to clean it. But as I mentioned earlier, it should slide out toward the front of the lens.
And I took the aperture ring and mount off for my picture, but it's not necessary to remove them if you're just trying to get the rear element out.

Last edited by .a.t.; 12-04-2018 at 01:54 AM. Reason: clarification & added a photo

stevebrot · 12-04-2018, 04:52 PM

Originally posted by .a.t.

If you already have some experience and the right tools, this Sigmatel is relatively easy to open.

Yay! A pro with pertinent experience!

Steve

**.a.t.** · 12-04-2018, 08:18 PM

Originally posted by stevebrot

Yay! A pro with pertinent experience!

Steve

A professional dilettante, perhaps...

Thank you, Steve.

12-03-2018, 01:11 AM	#1
Sniggi New Member Join Date: Dec 2018 Posts: 1	Sigmatel 135mm F1.8 YS Multi (How can i Open the Lens to clear it?) Hello, recently i bought a well worn sigmatel 135mm F1.8. The Lens has a lot of fungus in it and i was trying to Clean it but i couldnt find out how to open The Lens, to clean The glass elements. Is there a was to open it?

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12-03-2018, 12:18 PM	#2
noblepa Veteran Member Join Date: Sep 2007 Location: Bay Village, Ohio USA Posts: 1,142	I'm not familiar with that particular lens, but many lenses have a threaded retaining ring at the front of the lens. This ring usually has the name, focal length, aperture size and serial number engraved on it. I've read of a trick to unscrew the ring, in which a short piece of PVC pipe of the appropriate diameter, used with a rubber pad (sometimes used as a bottle opener) will give you enough grip to turn the ring and unscrew it. Alternatively, you could drill two small holes, opposite each other, into the ring and use an adjustable spanner wrench.

12-03-2018, 06:08 PM	#3
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Welcome to the Pentax Forums! Is this your lens? Sigmatel 135mm F1.8 "Multi Scalematic" Y/S Lens Reviews - Sigma Lenses - Pentax Lens Review Database It so, it might be worth getting a bid from a professional for the cleaning. There are quirks to opening every lens and most designs feature traps for the unwary. Taking a lens apart requires special tools, excellent dexterity, good eyesight, and patience. It also helps to have a description of what to expect since many lenses have a mixture of left and right-hand thread and some non-intuitive actions to get to the optical assemblies. In regards to special tools, if a Japanese camera or lens has a cross-head screw, it is most likely JIS head and not Philips-head. Using a Philips screwdriver carries the risk of stripping the head with few options to extract and salvage. I buy most of my camera repair tools from Micro-Tools. Their EU Web site is at: Micro-Tools Europe Tools \| Miniature Tools for Camera and Watch Repair Good luck. Steve P.S. Given that your lens is unusual and sort of rare, I would avoid drilling holes, if at all possible.

12-03-2018, 08:28 PM - 1 Like	#4
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by Sniggi Hello, recently i bought a well worn sigmatel 135mm F1.8. The Lens has a lot of fungus in it and i was trying to Clean it but i couldnt find out how to open The Lens, to clean The glass elements. Is there a was to open it? Hi Sniggi, If you already have some experience and the right tools, this Sigmatel is relatively easy to open. To get inside the front end, turn the focus ring to the minimum focus distance. Then you should see a small slot head screw above the focus ring. Loosen the screw just a couple turns - it doesn't need to be removed. (If the screw comes out, it'll be easy to lose and difficult to get back in place!) With that screw loosened, the front part of the lens can now be unscrewed counterclockwise. Then you'll have access to the front elements. With the top piece / retainer off, the front element should come out easily. Next, there's a spacer ring to lift out. And then a cemented triplet should also slide out easily. There are also two elements behind the iris. When the iris is wide open, I believe the next element will also fall forward and out. And to get the rear element out, you'll need a spanner wrench or similar tool. To remove the rear element, focus the lens to infinity and remove the mount adapter. Depending on which adapter you have on your lens, it might simply spin off, or it may require removing some screws first. When the adapter is off, you'll have easier access to the retaining ring so it can be removed with a spanner. Here's what my lens looked like when I had it apart for cleaning a few months ago: In the picture, the second to last element is still inside the lens because I didn't need to clean it. But as I mentioned earlier, it should slide out toward the front of the lens. And I took the aperture ring and mount off for my picture, but it's not necessary to remove them if you're just trying to get the rear element out. Last edited by .a.t.; 12-04-2018 at 01:54 AM. Reason: clarification & added a photo

12-04-2018, 04:52 PM	#5
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by .a.t. If you already have some experience and the right tools, this Sigmatel is relatively easy to open. Yay! A pro with pertinent experience! Steve

12-04-2018, 08:18 PM	#6
.a.t. Site Supporter Join Date: Mar 2011 Location: yesterday Photos: Gallery Posts: 1,261	Originally posted by stevebrot Yay! A pro with pertinent experience! Steve A professional dilettante, perhaps... Thank you, Steve.