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Will a fingerprint "bake in" one front refractor objective?

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#1 je2000

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Posted 01 August 2020 - 05:51 PM

I'm about ready to try out my new Quark Chromosphere. I forgot I have a single pristine fingerprint on the outer portion of my front objective. Suspect since it's not my fingerprint....

 

Anyway, normally I'd just leave it and wait until something else shows up before cleaning it. Since the glass will be pointed unfiltered directly into the sun I was wondering if it may become much harder to remove by doing so. I've already done plenty of white light exposure with Baader visual film, just never direct exposure.

 

Is this something to even consider? I'm not particularly up to cleaning it off right now since it's not noticeable while night time observing.



#2 BYoesle

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Posted 01 August 2020 - 06:21 PM

That's a good question. If it were me I'd bone up on appropriate cleaning methods and remove it rather than take a chance, especially if the AR coatings are soft versus hard (the Stellar view website on the SV102T is silent on this).


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#3 bigdob24

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Posted 01 August 2020 - 06:53 PM

I second the cleaning , that would really bother me


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#4 je2000

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Posted 03 August 2020 - 09:23 AM

Might be worth it to call Stellarvue anyway and maybe get some more info on their coatings.

The problem is I can't find the cleaning kit since I'm in the middle of moving into a new house. I set up everything in the new yard first thing. Priorities you know?

#5 MalVeauX

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Posted 03 August 2020 - 10:37 AM

Hi,

 

I'd clean it. I have lots of finger prints on lots of glass. Doesn't effect the view or imaging really as its way out of focus and the transmission loss from isn't detectable. At worst it may show up as a slight contrast hit in that area under extreme focal-ratio, but likely only detectable by camera sensor and then barely.

 

Wear some gloves or something and use cotton ball with distilled water and unscented basic soap. Dab. Don't rub. Dab. Rinse with dabbing distilled water on cotton ball. Dry with rocket blower and air. The coatings are way more durable than your finger tips by the way.

 

Very best,



#6 bigdob24

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Posted 03 August 2020 - 03:47 PM

Here is what a well known optician told me for lens cleaning and is very close to what Lunt recommends for cleaning there objectives

Ive removed spots with this method

 

You can make your own. Simply add 25% to 40% distilled water to isopropyl alcohol  It will clean off most pollen, but will not remove silver spots. These can be removed by rubbing in circular fashion with your fingertip wetted with your saliva, followed immediately with an alcohol wetted tissue. Do not wait, do not let it dry before the alcohol wipe!!

You can also try Purosol brand optical lens cleaner. It uses a mild soap based liquid to clean off organic materials. Stubborn spots won't come off with this stuff either, but there is always saliva (followed immediately with Purosol!!).

Why does saliva work on the most stubborn spots? It's a well known trick among opticians. Saliva has powerful enzymes that break down the most stubborn of organic compounds (and that's the basis of life). And don't worry, it won't eat the coatings since those are made of inert oxides. And fingertips will not scratch the surface, in fact every optician knows that fingers are nature's most gentle polishing pads. I use mine for final figuring on lenses.


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#7 chemman

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Posted 03 August 2020 - 05:45 PM

.... Saliva has powerful enzymes that break down the most stubborn of organic compounds (and that's the basis of life). And don't worry, it won't eat the coatings since those are made of inert oxides. And fingertips will not scratch the surface, in fact every optician knows that fingers are nature's most gentle polishing pads. I use mine for final figuring on lenses.

Amylase is one of many components of saliva.  It is the reason your kids love those french fries.  Amylase turns starch into sugar as you chew.  Just as well give the kids lollipops.   Lol

 

I would have to remove the finger print maybe blue painters tape gently on and off a few times. Maybe scotch tape, only use once just repeat with a new one. See what is left with a hand lens, then proceed with solvents, fingers etc.  


Edited by chemman, 03 August 2020 - 05:48 PM.


#8 Spikey131

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Posted 04 August 2020 - 02:00 PM

I clean all fingerprints off of my optics ASAP.  Oils from human skin can damage coatings.

 

Light from the sun would not likely influence this either way.  Light landing on your objective is not concentrated like it is near the eyepiece.

 

BTW, amylase converts starches to glucose (sometimes called blood sugar), not sucrose (cane sugar).  Glucose dose not trigger the lingual sweet sensors as sucrose does, so it does not taste sweet.  French fries are yummy from all that fat!



#9 briansalomon1

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Posted 04 August 2020 - 04:43 PM

Fingerprints have acid in the oils and will etch into the lens.

 

Here is the cleaning method the old timers taught at Litton/Northrop.

 

Take 4 Q-tips in your hand as shown and dampen the top Q-tip with a single drop of IPA. Isopropal alcohol is safe on all modern coatings. You don't need anything special, just 90% alcohol or better (higher water content dries slowly and results in smudges)

 

Using the damp Q-tip gently clean the lens in a circular motion starting in the center and working out. without pausing switch to the 3 dry Q-tips using the same motion until the surface is completely dry.

 

If the coatings are thin film metallized (and are really dirty) you can use the same procedure with Acetone. Acetone will leave a film and must be followed with IPA.

 

https://www.cloudyni...0200804-142839/


Edited by briansalomon1, 04 August 2020 - 04:45 PM.

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#10 chemman

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Posted 05 August 2020 - 03:24 AM

I clean all fingerprints off of my optics ASAP.  Oils from human skin can damage coatings.

 

Light from the sun would not likely influence this either way.  Light landing on your objective is not concentrated like it is near the eyepiece.

 

BTW, amylase converts starches to glucose (sometimes called blood sugar), not sucrose (cane sugar).  Glucose dose not trigger the lingual sweet sensors as sucrose does, so it does not taste sweet.  French fries are yummy from all that fat!

Two things my very old school Oganic Chemistry professor said was the children amalase starch to sugar and that the fat is where the flavor is at.  Glucose is still sweet as are all sugars.  Glucose is not near as sweet as many of the other sugars but as a budding chemist I had to check this out.  I took a small sample of a bunch of different sugars in the lab, Organic Chemisty professor would not have approved, and they were all pretty darn sweet.  High fructose corn syrup is used in manufacturing products because they can use so much less and get the desired sweetness. 

 

relativesweetnessofsugars.jpg.cf.jpg


Edited by chemman, 05 August 2020 - 03:26 AM.


#11 Spikey131

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Posted 05 August 2020 - 07:53 AM

Two things my very old school Oganic Chemistry professor said was the children amalase starch to sugar and that the fat is where the flavor is at.  Glucose is still sweet as are all sugars.  Glucose is not near as sweet as many of the other sugars but as a budding chemist I had to check this out.  I took a small sample of a bunch of different sugars in the lab, Organic Chemisty professor would not have approved, and they were all pretty darn sweet.  High fructose corn syrup is used in manufacturing products because they can use so much less and get the desired sweetness. 

 

attachicon.gifrelativesweetnessofsugars.jpg.cf.jpg

I stand corrected.



#12 chemman

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Posted 05 August 2020 - 11:07 PM

I stand corrected.

So I have read that honey is mostly dextrose and lesser amounts of glucose, enantimers, glucose being levarotary and dextrose dextrarotary.  Having bees I have a store of honey.  My wife won't  use it as sweetener, only when honey is called for.  I personally don't find honey to be all that sweet.  

 

So now I wonder if our OP @je2000 has removed his fingerprint and how?  



#13 je2000

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Posted 26 August 2020 - 08:53 AM

I took a microfiber cloth and used a mystery eyeglass solution from my Dr. It is probably just water and a tiny bit of soap. It is coating friendly as my glasses have all the coatings. It wasn't perfect but the smudge is gone.

Used the air puffer, small brush, spray cleaner on pad, and wipe gently.

Probably overthinking it all.

#14 je2000

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Posted 26 August 2020 - 08:53 AM

I took a microfiber cloth and used a mystery eyeglass solution from my Dr. It is probably just water and a tiny bit of soap. It is coating friendly as my glasses have all the coatings. It wasn't perfect but the smudge is gone.

Used the air puffer, small brush, spray cleaner on pad, and wipe gently.

Probably overthinking it all.

#15 KTAZ

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Posted 26 August 2020 - 09:24 AM

Probably overthinking it all.

Yup...everybody does.

 

The first rule to cleaning your optics is simply making sure you removed any dirt particles that will scratch your coatings before you use any type of wiping motion. Blow first then use an IPA and distilled water solution on pure cotton to “dab” and lift off any remaining dirt. Once that is done, you can use mild pressure (meaning the weight of the cotton ball or pad) to wipe gently and remove the deposit. Same for drying and polishing.

 

The second rule is not to use commercial lens cleaning solutions. They all leave residue. 90% or better IPA (99% preferred) plus distilled water is best.


Edited by KTAZ, 26 August 2020 - 09:25 AM.



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