The attached images are micrographs of the surface of an eyepiece which has been damaged by Aeroguard (or similar) I believe (feel free to correct me or add any other relevant detail Houghy!). The damage is to the coatings on the EP lens. It is evident the chemical(s) have eaten away part of the coating, resulting in glarey haloes around bright objects.
The first two images are at about 50x magnification (the white areas are light reflections within the EP). The remainder are of different sections of the lens surface at about 200x magnification.
The EP is Meade 24mm Series 5000 Ultra Wide Angle EP. Feel free to cry if you like...
That looks like some type of film on the lens not MgF etc.
I have read about some fella in the US who tried all kinds of solvents and chemicals who could not get any type of damage to the coating.
I suggest it is a non reflective polymer coating that has been damaged.
If it was me with an expensive eye pc like this I would dis-assemble the Ep and remove the damaged lense.
Then try to find what type of chemical/solvent that damaged the eye p/c and remove the damaged coating from the glass by rubbing a cloth wetted with the "solvent" until all the coating is removed.
What have you to loose? if you can clean up the damaged lens to a clean class state all you loose is one element loosing a coating to one side. Worth a few percent light loss and having a useable Ep again at no cost. http://www.cloudynights.com/ubbthrea.../o/all/fpart/1
Looks nasty Al , I thought todays coatings were pretty tolerant to solvents , no ones been having a fag at the eyepiece ? Have seen some pics of an eyelens with lots of little burns on it .
Oh yeah the coatings are tough alright. When Houghy gave me the EP he said "Clean this with whatever you like..." if I can get the surface clear, it's a step in the right direction.
You could be right, David. It may be a film on top of the coating. Still it's a tough film!
There must be some nasty stuff in insect repellents (and I suspect sunscreens) though. A mate of mine used Rid, and still had some on his hands when he picked up his camera. It started to dissolve the the plastic in his camera. It only affected the surface, but his camera has an ugly looking handprint permanently in the surface now. Finger print ID of ownership! ...and people happily put this stuff on their skin. Just shows how tough our skin is!
Al.
Last edited by sheeny; 11-08-2009 at 07:10 AM.
Reason: afterthought
The EP is Meade 24mm Series 5000 Ultra Wide Angle EP. Feel free to cry if you like...
Al.
Waaaah!!! Yep its nasty stuff alright - no wonder the bugs dont like it.
I did a similar thing to the lenses of some sunglasses not too long ago - except that I had petrol all over my hands (playing with my mower I was) and left some lovely permanant finger prints on the lenses.
There must be some nasty stuff in insect repellents (and I suspect sunscreens) though.
Yep... most include organic solvents for both hydrophobic and hydrophilic chemicals. Diphenylacrylate (dissolves most plastics) is pretty common, and they can include any of the following:
Ethanol
C12-15 Alcohols
Benzoate (Crodamol AB)
Dioctyl Maleate
Ceitol 868
Isopropyl Palmitate
Isopropyl Myristate
Silicone Fluid 345DC
Tridecyl Salicylate (Cosmacol ESI)
Butyloctyl Salicylate
Liquid Paraffin BP
Almond Oil BP
Deodorised Winter Sunflower Oil
Polydecene (Nexbase)
Xylene
Toluene
I'm with Eric, use roll-on Aerogard.
The other problem with sprays, whether it be insecticides, deodorants or air fresheners, is that the chemical cocktail of airborn droplets is going to be breathed into the lungs.
I can confirm that insect repellants totally stuff optical coatings. Last year at Snake Valley someone sprayed repellent near my Tak, and it destroyed the coating to the point I had to send the scope back to Japan. They were initially going to just remove the old coating and re-coat, but apparently the glass was damaged and the objective lenses had to be replaced totally. $6000.00 was the final cost including all the freight. Luckily I had all risks with my Insurance. So as far as I am concerned, any repellents used at least spray types do NOT belong anywhere near sensitive optical coatings.
Just for information, thinners (30% acetone, etc) and acetone free nail polish remover (ethyl acetate and isopropyl alcohol) won't touch it.
In fact careful examination reveals that a tiny section to one side of the lens is not damaged. The bad news is the "islands" that look like a coating on top of the coating are infact the remains of the original optical coating. It is well and truly etched!
6K to kill a few mozzies .. fair call on the aroguard
I know suncream is nasty stuff I once dropped a dolop on the cars bonnet by the beach by the time I locked up and wiped it off it took a fair swag of paint with it
Just one reason why I never use bug repellant. Personally I can't stand the stuff, both the gross oily feeling on the skin and the smell, plus I end up sneezing like hell should any of that garbage find its way near my nose.
I'd rather suffer hundreds of mozzie bites than use that feral crap they call Aeroguard. Besides mozzie bites are fun to scratch lol
I can confirm that insect repellants totally stuff optical coatings. Last year at Snake Valley someone sprayed repellent near my Tak, and it destroyed the coating to the point I had to send the scope back to Japan. They were initially going to just remove the old coating and re-coat, but apparently the glass was damaged and the objective lenses had to be replaced totally. $6000.00 was the final cost including all the freight. Luckily I had all risks with my Insurance. So as far as I am concerned, any repellents used at least spray types do NOT belong anywhere near sensitive optical coatings.
I'd rather suffer hundreds of mozzie bites than use that feral crap they call Aeroguard. Besides mozzie bites are fun to scratch lol
Even in southern Australia mosquitoes can carry nasty infectious diseases. I spray RID on my clothing though I might switch to roll-on after reading this thread. I had no idea of the danger to optics.
Combined Ross River/Barmah Forest Virus notifications for last year = 6500. (263 in Victoria). Both diseases have affected my family.
I got a small amount of sunscreen on the edge of a polycarbonate lens in my glasses a few years back and didn't notice it immediately. The lens cracked in half an hour later while I was wearing the glasses.
Finger print ID of ownership!
...and people happily put this stuff on their skin.
Just shows how tough our skin is!
. It is well and truly etched!
