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guardian
Joined: 18 Mar 2009 Posts: 1747
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Posted: Wed Jun 21, 2017 11:24 am Post subject: Repairing rear lens element scratches/gouges |
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guardian wrote:
Damage to rear lens element is always a concern. Here is how one chap dealt with this dilemma:
http://www.instructables.com/id/Fixing-the-Dreaded-Scratch-on-Rear-Element-of-a-Le/ |
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visualopsins
Joined: 05 Mar 2009 Posts: 10463 Location: California
Expire: 2021-06-22
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Posted: Sat Sep 02, 2017 2:47 pm Post subject: |
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visualopsins wrote:
windscreen repair kit -- of course! Best of all it seems to have repaired severe rear element scratches... _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony A7Rii, Spotmatics II, F, and ESII, Nikon P4
M42 Asahi Optical Co., Lenses:
Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200
Tele-Takumar 1:5.6/200, 1:6.3/300
Macro-Takumar 1:4/50
Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm
Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element),
Super-Multi-Coated Fisheye-TAKUMAR 1:4/17
Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500
Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100
Super-Multi-Coated Bellows-TAKUMAR 1:4/100
SMC TAKUMAR 1:1.4/50, 1:1.8/55
Other lenses:
Carl Zeiss Jena Flektogon 2.4/35
SMC PENTAX ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto
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Lightshow
Joined: 04 Nov 2011 Posts: 3669 Location: Calgary
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Posted: Sat Sep 09, 2017 4:08 pm Post subject: |
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Lightshow wrote:
Hard to say how it will perform with colour pictures, I wonder if optical UV cure glue would perform better? _________________ A Manual Focus Junky...
One photographers junk lens is an artists favorite tool.
My lens list
http://www.flickr.com/photos/lightshow-photography/ |
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dan_
Joined: 05 Dec 2012 Posts: 1052 Location: Romania
Expire: 2016-12-19
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Posted: Sun Sep 10, 2017 12:25 am Post subject: |
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dan_ wrote:
As long as the scratches remain visible but no more detectable with the finger there are no improvements in IQ or in the overall aspect of the lens. The IQ and coatings could degradate because of the new layer applied.
My conclusion - DON'T DO THIS AT HOME! |
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visualopsins
Joined: 05 Mar 2009 Posts: 10463 Location: California
Expire: 2021-06-22
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Posted: Sun Sep 10, 2017 1:38 am Post subject: |
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visualopsins wrote:
dan_ wrote: |
As long as the scratches remain visible but no more detectable with the finger there are no improvements in IQ or in the overall aspect of the lens. The IQ and coatings could degradate because of the new layer applied.
My conclusion - DON'T DO THIS AT HOME! |
+1
This is Great Advice for example those lenses with rear elements showing many cleaning scratches... Fingernail is surprising sensitive! Everybody knows the best lens grinders outperformed machinery for many many years, due to finger sensitivity. _________________ ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮ like attracts like! ☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮☮
Cameras: Sony A7Rii, Spotmatics II, F, and ESII, Nikon P4
M42 Asahi Optical Co., Lenses:
Takumar 1:4 f=35mm, 1:2 f=58mm (Sonnar), 1:2.4 f=58mm (Heliar), 1:2.2 f=55mm (Gaussian), 1:2.8 f=105mm (Model I), 1:2.8/105 (Model II), 1:5.6/200
Tele-Takumar 1:5.6/200, 1:6.3/300
Macro-Takumar 1:4/50
Auto-Takumar 1:2.3 f=35, 1:1.8 f=55mm, 1:2.2 f=55mm
Super-TAKUMAR 1:3.5/28 (fat), 1:2/35 (Fat), 1:1.4/50 (8-element),
Super-Multi-Coated Fisheye-TAKUMAR 1:4/17
Super-Multi-Coated TAKUMAR 1:4.5/20, 1:3.5/24, 1:3.5/28, 1:2/35, 1:3.5/35, 1:1.8/85, 1:1.9/85 1:2.8/105, 1:3.5/135, 1:2.5/135 (II), 1:4/150, 1:4/200, 1:4/300, 1:4.5/500
Super-Multi-Coated Macro-TAKUMAR 1:4/50, 1:4/100
Super-Multi-Coated Bellows-TAKUMAR 1:4/100
SMC TAKUMAR 1:1.4/50, 1:1.8/55
Other lenses:
Carl Zeiss Jena Flektogon 2.4/35
SMC PENTAX ZOOM 1:3.5 35~105mm, SMC PENTAX ZOOM 1:4 45~125mm
Nikon Micro-NIKKOR-P-C Auto 1:3.5 f=55mm, NIKKOR-P Auto 105mm f/2.5 Pre-AI (Sonnar), Micro-NIKKOR 105mm 1:4 AI, NIKKOR AI-S 35-135mm f/3,5-4,5
Tamron SP 17mm f/3.5 (51B), Tamron SP 17mm f/3.5 (51BB), SP 500mm f/8 (55BB), SP 70-210mm f/3.5 (19AH)
Vivitar 100mm 1:2.8 MC 1:1 Macro Telephoto
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baychlen
Joined: 17 Aug 2017 Posts: 39 Location: Spain +/- 3000km
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Posted: Sun Sep 17, 2017 2:38 pm Post subject: |
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baychlen wrote:
LOL! WOW! Epoxy on optical glass_!_ Even idiot like me would not do such a barbarian thing... There are parameters like lines per milimeter for the resolution, I read there are polishing services here and there, but what you get, polishing epoxy?!? And polishing only from outside. The main problem I suppose is teh IOR, index of refraction, or whatever it is called, the optical angle of the passing light I mean. I would buy a broken copy of the lens on ebay and change an element, if available of course. Maybe a similar element can be put too - then make photos and share on flickr as DIY bokeh monster, not a bad idea.
Cheerz! _________________ 100% DIY homegrown amateur
KO-140M f1.8, 120 f1.8 / 35KM140 f1.8 / Kipronar 90 f1.9, 105 f1.9, 120 f1.9, 140 f1.9, 165 f2.2, 180 f2.2, 200 f2.1 / Visionar 55 f1.6, 130 f1.9, 141 f1.9, 154 f1.9/ Sonnar 180 f2.8 / Beseler 457 f3.5 / Pancolar 50 f1.8 / RO501-1 f2, 502-1 f2, 503-1 f2 / P5 150 f2, 180 f2 / Helios 44-2 f2 / Industar 51, 37 / Kinostar 125, 150 / Tair-3S 300 f4.5 / Pentacon 80 f2.8 / Diaplan 80 f2.8 / Mir-1B 37 / Triplet-6M 100 f2.8, 365 f3.65 / Jupiter 37A / Senkor 150 f2.5 / Leitz Wetzlar 150 f2.5 / Porst 135 f2.8, 35 f2.8 / Rokinon 135 f2.8 / Panorama 200 f3.5 / Meopta 50 f1 / RO-1091A f1.2 / Prokinar 90 f1.9 |
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DConvert
Joined: 12 Jun 2010 Posts: 901 Location: Essex UK
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Posted: Mon Sep 18, 2017 8:51 am Post subject: |
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DConvert wrote:
baychlen wrote: |
LOL! WOW! Epoxy on optical glass_!_ Even idiot like me would not do such a barbarian thing... There are parameters like lines per milimeter for the resolution, I read there are polishing services here and there, but what you get, polishing epoxy?!? And polishing only from outside. The main problem I suppose is teh IOR, index of refraction, or whatever it is called, the optical angle of the passing light I mean. I would buy a broken copy of the lens on ebay and change an element, if available of course. Maybe a similar element can be put too - then make photos and share on flickr as DIY bokeh monster, not a bad idea.
Cheerz! |
Refractive index varies with wavelength, and the way it varies depends on the glass (a property called dispersion). Any quality lens will use at least 2 different types of glass ('crown' & 'flint' being the early favorites though 'low dispersion', 'extra low dispersion' etc. have become common more recently). The epoxy can't automatically match it's properties to the glass it's applied too.
The epoxy is probably designed to closely match the typical refractive index of windscreen glass, the change in dispersion unlikely to be an issue for windscreens, but will often be for lenses. It will be closer to optical glass than air is, so might show some improvement over the untreated lens, but with more critical subjects I'm sure the errors will show clearly.
Adding dispersion into the equation makes this approach even worse than you make out. The age old approach of simply filling the scratches with matt black paint to remove their contribution to the image is far preferable IMO. |
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dan_
Joined: 05 Dec 2012 Posts: 1052 Location: Romania
Expire: 2016-12-19
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Posted: Mon Sep 18, 2017 9:00 am Post subject: |
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dan_ wrote:
DConvert wrote: |
The age old approach of simply filling the scratches with matt black paint to remove their contribution to the image is far preferable IMO. |
I fully agree. |
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