Fingerprint on rear element, what to do?

Fenwoodian · 08-06-2019, 07:01 PM

Originally posted by stevebrot

Naphta will often leave a residue and acetone will attach many plastics (not safe around cameras or lenses). Full strength alcohol (IPO included) is also contraindicated because of its strong solvent action.

Blower followed by fog with breath for lubrication and clean microfibre cloth. The magic of the microfibre cloth is that it will wick oils off the glass surface. That failing, 50% isopropanol in water on a soft cotton cloth followed by gentle drying with the unwetted portion of the cloth.

Steve

(...truth be told, I use Windex on the corner of a soft cotton cloth...but I would be pilloried for suggesting such...)

You do it your way and I'll do it mine. I've repaired, adapted, CLA'ed many lenses as decribed with no residue or other problems - provided you know what you're doing!

stevebrot · 08-06-2019, 08:05 PM - **1 Like**

Originally posted by Fenwoodian

You do it your way and I'll do it mine. I've repaired, adapted, CLA'ed many lenses as decribed with no residue or other problems - provided you know what you're doing!

Fair enough...the OP does not know what they are doing, hence the more conservative advice for a task that may be done many different ways. As for hands-on experience show 'n tell...ain't gonna go there...

Steve

stevebrot · 08-06-2019, 08:08 PM

Originally posted by Not a Number

Ever since I stripped off the coating on the rear element of a teleconverter with some isopropyl alcohol back in the 80s alcohol doesn't go anywhere near my lenses. I certainly wouldn't use 75% or greater. Alcohol is rather reactive stuff - it will damage many plastics, rubbers, finishes and metallic surfaces.

Yep!

I am not that cautious, but am wary of "strong" solvent action.

Steve

(...have ancient background with differential solvent chemistry...)

Silent Street · 08-06-2019, 10:41 PM

Brush the element first. Then use Windex or commercial eyeglass cleaner on a clean microfibre cloth in a light circular fashion starting from the centre and working outward. No rocket science involved, but realise you are scrubbing a very high precision part of the lens.

Benz3ne · 08-07-2019, 01:28 AM

The echo some of the suggestions above, I'd go blower first, cotton bud with 70:30 isopropyl:water with a cotton bud, cotton bud to dry and blower again to remove any final dusts.

Has worked for me with a number of recently-acquired lenses which, although don't have fingerprints (which is just an oil residue anyway, iPrOH will take care of that) have had some grubby marks which have all shifted easily with the technique I've used.

Dartmoor Dave · 08-07-2019, 01:57 AM - **3 Likes**

Optical grade glass with a multicoating bonded to it on a molecular level is so fragile that the only safe method is to use the wing of a butterfly dipped in fresh morning dewdrops from the petals of a wild rose. Anything harsher will rip out deep gouges in the glass and make the lens unusable.

But seriously, do what @stevebrot says. Give it a blast with a blower, breathe on it, and wipe with a microfiber. I've never found anything that cleans any lens better than that.

Lev · 08-07-2019, 03:21 AM

Originally posted by Benz3ne

The echo some of the suggestions above, I'd go blower first, cotton bud with 70:30 isopropyl:water with a cotton bud, cotton bud to dry and blower again to remove any final dusts.

Has worked for me with a number of recently-acquired lenses which, although don't have fingerprints (which is just an oil residue anyway, iPrOH will take care of that) have had some grubby marks which have all shifted easily with the technique I've used.

but did you do that on rear element? or it doesnt matter?

Benz3ne · 08-07-2019, 03:23 AM

Originally posted by Lev

but did you do that on rear element? or it doesnt matter?

Yes, both front and rear elements. If I'm doing a quick 'tidy up' of a lens (mine are often seen down the beach) it's blower, ensure physical particulates are away from the centre with very light touches of a cotton bud, clean cloth and breath, blower again. It's worked fine for me so far and I'm sure it'll continue to.

Lev · 08-07-2019, 03:25 AM

Originally posted by Dartmoor Dave

Optical grade glass with a multicoating bonded to it on a molecular level is so fragile that the only safe method is to use the wing of a butterfly dipped in fresh morning dewdrops from the petals of a wild rose. Anything harsher will rip out deep gouges in the glass and make the lens unusable.

But seriously, do what @stevebrot says. Give it a blast with a blower, breathe on it, and wipe with a microfiber. I've never found anything that cleans any lens better than that.

From what you are saying, it must never be touched with anything. How to remove it then? Breath is worst idea imo, you are transferring just who knows what kind of materials including acids and etc that way

Benz3ne · 08-07-2019, 03:28 AM - **2 Likes**

Originally posted by Lev

From what you are saying, it must never be touched with anything. How to remove it then? Breath is worst idea imo, you are transferring just who knows what kind of materials including acids and etc that way

I think you have, perhaps, missed their British humour. Breath isn't that bad. It's mostly water vapour. If you were breathing acids of any dangerous pH or quantity you'd probably be in a hospital or worse.

Dartmoor Dave · 08-07-2019, 09:00 AM - **1 Like**

Originally posted by Lev

From what you are saying, it must never be touched with anything. How to remove it then? Breath is worst idea imo, you are transferring just who knows what kind of materials including acids and etc that way

My apologies Lev. As Benz3ne says, the British sense of irony doesn't always make any sense at all in other countries.

So this is a serious answer. The air we breathe out is mostly nitrogen, with some oxygen, some carbon dioxide, some water vapour, and a tiny percentage of other trace elements. Unless you've just breathed in something loaded with particulates, such as cigarette smoke, breathing on your lens won't cause any harm at all. Any saliva in your breath is sterile and usually PH neutral, so the idea that you might be breathing acid onto the lens is really just an internet myth. There might be some germs in there if you've got an infection, but they won't harm your lens since you'll be wiping them off with the microfiber anyway.

Lev · 08-07-2019, 10:31 AM

Originally posted by Dartmoor Dave

My apologies Lev. As Benz3ne says, the British sense of irony doesn't always make any sense at all in other countries.

So this is a serious answer. The air we breathe out is mostly nitrogen, with some oxygen, some carbon dioxide, some water vapour, and a tiny percentage of other trace elements. Unless you've just breathed in something loaded with particulates, such as cigarette smoke, breathing on your lens won't cause any harm at all. Any saliva in your breath is sterile and usually PH neutral, so the idea that you might be breathing acid onto the lens is really just an internet myth. There might be some germs in there if you've got an infection, but they won't harm your lens since you'll be wiping them off with the microfiber anyway.

Sorry I didn't get the humor but that's temporary thing, fly to georgia we will then exchange with some

Argh.. back to the lens, I'm preparing for this operation like a surgeon in hospital.

Soft brush, microfiber cloth, IPA, distilled water, medical gloves and lot of my nerves.

Breath or not, something must be in contact with the rear element to take that fingerprint off. That's the main problem I'm afraid of.

stevebrot · 08-07-2019, 10:52 AM - **2 Likes**

Originally posted by Lev

Breath or not, something must be in contact with the rear element to take that fingerprint off. That's the main problem I'm afraid of.

Be gentle and don't scrub. It will turn out fine.

Steve

Lev · 08-07-2019, 11:11 AM

Originally posted by stevebrot

Be gentle and don't scrub. It will turn out fine.

Steve

thanks Steve!

Lev · 08-09-2019, 07:09 AM

Well, things are not that good, couldn't remove smear completely but I think I've screwed up as there is something which looks like a scratch on daylight bulb but on direct sunlight it looks like another line of smear. I'm not sure but I think it's scratched. Now I hell afraid to touch front. I knew instantly that things will go very bad when I touched the rear element with my fff finger. Take care of your gear guys but not too much because sometimes it leads to worst.

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08-06-2019, 07:01 PM	#16
Fenwoodian Pentaxian Join Date: Apr 2015 Location: USA Photos: Gallery \| Albums Posts: 2,874	Originally posted by stevebrot Naphta will often leave a residue and acetone will attach many plastics (not safe around cameras or lenses). Full strength alcohol (IPO included) is also contraindicated because of its strong solvent action. Blower followed by fog with breath for lubrication and clean microfibre cloth. The magic of the microfibre cloth is that it will wick oils off the glass surface. That failing, 50% isopropanol in water on a soft cotton cloth followed by gentle drying with the unwetted portion of the cloth. Steve (...truth be told, I use Windex on the corner of a soft cotton cloth...but I would be pilloried for suggesting such...) You do it your way and I'll do it mine. I've repaired, adapted, CLA'ed many lenses as decribed with no residue or other problems - provided you know what you're doing!

08-06-2019, 08:05 PM - 1 Like	#17
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Fenwoodian You do it your way and I'll do it mine. I've repaired, adapted, CLA'ed many lenses as decribed with no residue or other problems - provided you know what you're doing! Fair enough...the OP does not know what they are doing, hence the more conservative advice for a task that may be done many different ways. As for hands-on experience show 'n tell...ain't gonna go there... Steve

08-06-2019, 08:08 PM	#18
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Not a Number Ever since I stripped off the coating on the rear element of a teleconverter with some isopropyl alcohol back in the 80s alcohol doesn't go anywhere near my lenses. I certainly wouldn't use 75% or greater. Alcohol is rather reactive stuff - it will damage many plastics, rubbers, finishes and metallic surfaces. Yep! I am not that cautious, but am wary of "strong" solvent action. Steve (...have ancient background with differential solvent chemistry...)

08-06-2019, 10:41 PM	#19
Silent Street Veteran Member Join Date: Nov 2011 Location: Castlemaine, Victoria, AUS Photos: Albums Posts: 1,151	Brush the element first. Then use Windex or commercial eyeglass cleaner on a clean microfibre cloth in a light circular fashion starting from the centre and working outward. No rocket science involved, but realise you are scrubbing a very high precision part of the lens.

08-07-2019, 01:28 AM	#20
Benz3ne Pentaxian Join Date: Jun 2019 Location: Cymru Posts: 2,356	The echo some of the suggestions above, I'd go blower first, cotton bud with 70:30 isopropyl:water with a cotton bud, cotton bud to dry and blower again to remove any final dusts. Has worked for me with a number of recently-acquired lenses which, although don't have fingerprints (which is just an oil residue anyway, iPrOH will take care of that) have had some grubby marks which have all shifted easily with the technique I've used.

08-07-2019, 01:57 AM - 3 Likes	#21
Dartmoor Dave Pentaxian Join Date: Aug 2012 Location: Dartmoor, UK Photos: Gallery Posts: 3,882	Optical grade glass with a multicoating bonded to it on a molecular level is so fragile that the only safe method is to use the wing of a butterfly dipped in fresh morning dewdrops from the petals of a wild rose. Anything harsher will rip out deep gouges in the glass and make the lens unusable. But seriously, do what @stevebrot says. Give it a blast with a blower, breathe on it, and wipe with a microfiber. I've never found anything that cleans any lens better than that.

08-07-2019, 03:21 AM	#22
Lev Veteran Member Join Date: Aug 2015 Location: Tbilisi, Georgia Posts: 1,197 Original Poster	Originally posted by Benz3ne The echo some of the suggestions above, I'd go blower first, cotton bud with 70:30 isopropyl:water with a cotton bud, cotton bud to dry and blower again to remove any final dusts. Has worked for me with a number of recently-acquired lenses which, although don't have fingerprints (which is just an oil residue anyway, iPrOH will take care of that) have had some grubby marks which have all shifted easily with the technique I've used. but did you do that on rear element? or it doesnt matter?

08-07-2019, 03:23 AM	#23
Benz3ne Pentaxian Join Date: Jun 2019 Location: Cymru Posts: 2,356	Originally posted by Lev but did you do that on rear element? or it doesnt matter? Yes, both front and rear elements. If I'm doing a quick 'tidy up' of a lens (mine are often seen down the beach) it's blower, ensure physical particulates are away from the centre with very light touches of a cotton bud, clean cloth and breath, blower again. It's worked fine for me so far and I'm sure it'll continue to.

08-07-2019, 03:25 AM	#24
Lev Veteran Member Join Date: Aug 2015 Location: Tbilisi, Georgia Posts: 1,197 Original Poster	Originally posted by Dartmoor Dave Optical grade glass with a multicoating bonded to it on a molecular level is so fragile that the only safe method is to use the wing of a butterfly dipped in fresh morning dewdrops from the petals of a wild rose. Anything harsher will rip out deep gouges in the glass and make the lens unusable. But seriously, do what @stevebrot says. Give it a blast with a blower, breathe on it, and wipe with a microfiber. I've never found anything that cleans any lens better than that. From what you are saying, it must never be touched with anything. How to remove it then? Breath is worst idea imo, you are transferring just who knows what kind of materials including acids and etc that way

08-07-2019, 03:28 AM - 2 Likes	#25
Benz3ne Pentaxian Join Date: Jun 2019 Location: Cymru Posts: 2,356	Originally posted by Lev From what you are saying, it must never be touched with anything. How to remove it then? Breath is worst idea imo, you are transferring just who knows what kind of materials including acids and etc that way I think you have, perhaps, missed their British humour. Breath isn't that bad. It's mostly water vapour. If you were breathing acids of any dangerous pH or quantity you'd probably be in a hospital or worse.

08-07-2019, 09:00 AM - 1 Like	#26
Dartmoor Dave Pentaxian Join Date: Aug 2012 Location: Dartmoor, UK Photos: Gallery Posts: 3,882	Originally posted by Lev From what you are saying, it must never be touched with anything. How to remove it then? Breath is worst idea imo, you are transferring just who knows what kind of materials including acids and etc that way My apologies Lev. As Benz3ne says, the British sense of irony doesn't always make any sense at all in other countries. So this is a serious answer. The air we breathe out is mostly nitrogen, with some oxygen, some carbon dioxide, some water vapour, and a tiny percentage of other trace elements. Unless you've just breathed in something loaded with particulates, such as cigarette smoke, breathing on your lens won't cause any harm at all. Any saliva in your breath is sterile and usually PH neutral, so the idea that you might be breathing acid onto the lens is really just an internet myth. There might be some germs in there if you've got an infection, but they won't harm your lens since you'll be wiping them off with the microfiber anyway.

08-07-2019, 10:31 AM	#27
Lev Veteran Member Join Date: Aug 2015 Location: Tbilisi, Georgia Posts: 1,197 Original Poster	Originally posted by Dartmoor Dave My apologies Lev. As Benz3ne says, the British sense of irony doesn't always make any sense at all in other countries. So this is a serious answer. The air we breathe out is mostly nitrogen, with some oxygen, some carbon dioxide, some water vapour, and a tiny percentage of other trace elements. Unless you've just breathed in something loaded with particulates, such as cigarette smoke, breathing on your lens won't cause any harm at all. Any saliva in your breath is sterile and usually PH neutral, so the idea that you might be breathing acid onto the lens is really just an internet myth. There might be some germs in there if you've got an infection, but they won't harm your lens since you'll be wiping them off with the microfiber anyway. Sorry I didn't get the humor but that's temporary thing, fly to georgia we will then exchange with some Argh.. back to the lens, I'm preparing for this operation like a surgeon in hospital. Soft brush, microfiber cloth, IPA, distilled water, medical gloves and lot of my nerves. Breath or not, something must be in contact with the rear element to take that fingerprint off. That's the main problem I'm afraid of.

08-07-2019, 10:52 AM - 2 Likes	#28
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Lev Breath or not, something must be in contact with the rear element to take that fingerprint off. That's the main problem I'm afraid of. Be gentle and don't scrub. It will turn out fine. Steve

08-07-2019, 11:11 AM	#29
Lev Veteran Member Join Date: Aug 2015 Location: Tbilisi, Georgia Posts: 1,197 Original Poster	Originally posted by stevebrot Be gentle and don't scrub. It will turn out fine. Steve thanks Steve!

08-09-2019, 07:09 AM	#30
Lev Veteran Member Join Date: Aug 2015 Location: Tbilisi, Georgia Posts: 1,197 Original Poster	Well, things are not that good, couldn't remove smear completely but I think I've screwed up as there is something which looks like a scratch on daylight bulb but on direct sunlight it looks like another line of smear. I'm not sure but I think it's scratched. Now I hell afraid to touch front. I knew instantly that things will go very bad when I touched the rear element with my fff finger. Take care of your gear guys but not too much because sometimes it leads to worst.