Cleaning haze on old lenses

Mojo_fish · 03-24-2008, 06:05 AM

Dear all,
I just bought a Pentax SMC-M 100mm f/4 macro lens from someone. There was some haze on the front element of the lens so I disassembled it to take closer look. I stripped the glass from its metal casing. The front element looks like it has two layers of glass glued together and the haze looks to be in between the two layers of glass. This could be attributable to the cementing compounds used to glue the two layers together. Is there a way to clean/dissolve this residue? Does heating the lens help? I'm appealing to all experts on cleaning glass....
best regards

frank · 03-25-2008, 09:40 PM

Originally posted by Mojo_fish

Dear all,
I just bought a Pentax SMC-M 100mm f/4 macro lens from someone. There was some haze on the front element of the lens so I disassembled it to take closer look. I stripped the glass from its metal casing. The front element looks like it has two layers of glass glued together and the haze looks to be in between the two layers of glass. This could be attributable to the cementing compounds used to glue the two layers together. Is there a way to clean/dissolve this residue? Does heating the lens help? I'm appealing to all experts on cleaning glass....
best regards

By my limited knowledge, haze is pretty easy to clean, but fog isn't. Your case sounds like foggy to me. If it's between two elements, don't think it'd be easy to fixed unless you change the elements together.

BTW, here is the optical formular of the M100/4 macro lens:

It's 5 elements in 3 groups structure. The front two elements are cemented together.

**Tyama** · 03-26-2008, 12:16 AM

I had a 100mm f/4 macro lens with the same problem. I disassembled and heated the element but it did not work.

**baldeagle21b** · 03-26-2008, 02:17 AM

Originally posted by Mojo_fish

Dear all,
I just bought a Pentax SMC-M 100mm f/4 macro lens from someone. There was some haze on the front element of the lens so I disassembled it to take closer look. I stripped the glass from its metal casing. The front element looks like it has two layers of glass glued together and the haze looks to be in between the two layers of glass. This could be attributable to the cementing compounds used to glue the two layers together. Is there a way to clean/dissolve this residue? Does heating the lens help? I'm appealing to all experts on cleaning glass....
best regards

I think your best bet is to find another lens with some other defect but with a clear front element and do a swap. Depending on the cement used, it might be possible to soak the two-layer element in a solvent to separate them and then re-cement them with special UV-cure cement, but that's a long shot at best.

03-24-2008, 06:05 AM	#1
Mojo_fish Junior Member Join Date: Oct 2007 Location: Netherlands Posts: 35	Cleaning haze on old lenses Dear all, I just bought a Pentax SMC-M 100mm f/4 macro lens from someone. There was some haze on the front element of the lens so I disassembled it to take closer look. I stripped the glass from its metal casing. The front element looks like it has two layers of glass glued together and the haze looks to be in between the two layers of glass. This could be attributable to the cementing compounds used to glue the two layers together. Is there a way to clean/dissolve this residue? Does heating the lens help? I'm appealing to all experts on cleaning glass.... best regards

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03-25-2008, 09:40 PM	#2
frank Veteran Member Join Date: Nov 2006 Location: Singapore Photos: Gallery Posts: 3,202	Originally posted by Mojo_fish Dear all, I just bought a Pentax SMC-M 100mm f/4 macro lens from someone. There was some haze on the front element of the lens so I disassembled it to take closer look. I stripped the glass from its metal casing. The front element looks like it has two layers of glass glued together and the haze looks to be in between the two layers of glass. This could be attributable to the cementing compounds used to glue the two layers together. Is there a way to clean/dissolve this residue? Does heating the lens help? I'm appealing to all experts on cleaning glass.... best regards By my limited knowledge, haze is pretty easy to clean, but fog isn't. Your case sounds like foggy to me. If it's between two elements, don't think it'd be easy to fixed unless you change the elements together. BTW, here is the optical formular of the M100/4 macro lens: It's 5 elements in 3 groups structure. The front two elements are cemented together.

03-26-2008, 12:16 AM	#3
Tyama Site Supporter Join Date: Mar 2007 Location: Honolulu, Hawaii Photos: Gallery Posts: 92	I had a 100mm f/4 macro lens with the same problem. I disassembled and heated the element but it did not work.

03-26-2008, 02:17 AM	#4
baldeagle21b Site Supporter Join Date: Nov 2006 Posts: 223	Originally posted by Mojo_fish Dear all, I just bought a Pentax SMC-M 100mm f/4 macro lens from someone. There was some haze on the front element of the lens so I disassembled it to take closer look. I stripped the glass from its metal casing. The front element looks like it has two layers of glass glued together and the haze looks to be in between the two layers of glass. This could be attributable to the cementing compounds used to glue the two layers together. Is there a way to clean/dissolve this residue? Does heating the lens help? I'm appealing to all experts on cleaning glass.... best regards I think your best bet is to find another lens with some other defect but with a clear front element and do a swap. Depending on the cement used, it might be possible to soak the two-layer element in a solvent to separate them and then re-cement them with special UV-cure cement, but that's a long shot at best.

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