Telescope care

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Hi,
I was out doing some observing last night and a large amount of due got on my equipment. Everything looks alright but the eyepieces look pretty dirty, so I was wondering the best way to clean them. I have looked on line a bit and some places suggest 91% pure isopropyl alcohol and some suggest distilled water.

I am just wondering, does anyone have any advice on the best method and what to use to clean eyepieces? Thanks for the help.
 

Answers and Replies

  • #2
Chronos
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Methanol is good, as is optical lens cleaning solution. Use distilled water to rinse away the cleaning solution. Opticians recommend a lens brush or compressed air [like the kind used on circuit boards] to remove simple dust. I would steer clear of lens wipes.
 
  • #3
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For light dust and dirt I just use compressed air.

On the rare occasion I have to 'clean' my eyepieces I use 99% Isopropyl alcohol and distilled water in a 50 /50 ratio.

You can produce your own distilled water with a kettle or pot or you can usually purchase it along with 99% Isopropyl alcohol from a pharmacy.

I also have a couple of cloths I obtained from an optical shop. They are very soft and lint free.
I keep them in a covered box to keep them dust free and clean.

This may seem be a bit overboard but I don't want to take chances with expensive eyepieces or optics.
 
  • #4
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Great! Thanks for the advice. I will probably go get some stuff from the pharmacy tomorrow. Course its supposed to rain for like a week so I guess there is no rush.
 
  • #5
russ_watters
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For light dust and dirt I just use compressed air.
Is that "real" compressed air or "compressed air" in a can that you buy at a computer store? I'd be wary of using the stuff you buy in a computer store because it is actually a liquid hydrocarbon similar to propane and I've found if some of the liquid comes out, it can leave a residue on what you are cleaning.
 
  • #6
turbo
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Is that "real" compressed air or "compressed air" in a can that you buy at a computer store? I'd be wary of using the stuff you buy in a computer store because it is actually a liquid hydrocarbon similar to propane and I've found if some of the liquid comes out, it can leave a residue on what you are cleaning.
Yep! That stuff spatters and makes things worse, especially if the can is really full or is inadvertently agitated. If you can't get the dust off with a squeeze bulb and want to do a gentle cleaning, I suggest the 50:50 Iso:water mix. Those are both solvents, and together they will remove a wide range of contaminants, including sweat, skin oils, and any pollen, dust or other solids embedded in them. When I was making and refitting lenses to eyeglasses, that is the only cleaning agent that I ever used on the glasses and frames. It is safe for anti-reflective coatings, UV coatings, etc, and does a really good job. Just don't "scrub" an optical surface with it until solid contaminants have been flushed away. Gentle wiping with Kim-wipes or other optical tissue with the mix will do the job.

Rule #1: Don't clean optics unless you have to, and then do the job as gently as possible.

If you have a little dirt on an objective lens or on a primary mirror, the image degradation will be minimal, and you can do far more harm that good by cleaning.
 
  • #7
chroot
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Eek.... cleaning lenses properly is much more difficult than just throwing some rubbing alcohol on a cloth and scrubbing away. The best advice I can give you is DON'T CLEAN YOUR LENSES. That's right, just don't. You almost definitely don't need to.

Dew is virtually pure water, and should evaporate away without leaving a trace. You do not have to clean a telescope after it has been exposed to dew. If it leaves spots, then you likely had pretty dirty optics to begin with.

It's extremely easy to sleek your optics when using any kind of cloth, so I'd advise that you never touch your optics with any cloth of any sort.

Water/alcohol baths are pretty safe. Even better is a product called "collodion," which is cellulose dissolved in ether. You pour it over the lens/mirror, wait for it to dry, and peel it off. It leaves an antiseptic, perfectly clean surface, free of dust, fingerprints, skin oils, etc.

- Warren
 
  • #8
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Is that "real" compressed air or "compressed air" in a can that you buy at a computer store? I'd be wary of using the stuff you buy in a computer store because it is actually a liquid hydrocarbon similar to propane and I've found if some of the liquid comes out, it can leave a residue on what you are cleaning.
I agree, I would not use the computer store 'stuff'.
I get compressed air in a can from one of the local photo shops. It is suppose to be dry air without any CFCs.

I don't use it all that often so a can lasts quite a while.
Not totally sure but I believe it is call 'Dust Gun' or something like that. I use it on my camera lenses and found it good on eyepieces and such.
 
  • #9
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We are talking about eyepieces right? I don't intend on cleaning the mirror only the eyepieces. I heard that this wasn't too dangerous, is that wrong? Should I avoid doing this if at all possible? There are quite a few specs all over the side of the eyepiece that your eye is close to.

Also where do you purchase one of these squeeze air bulbs?
 
  • #10
Chronos
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For consideration:

HOW TO CLEAN MIRRORS AND LENSES
by Lenny Abbey, <LAbbeymindspring.com>

The cleaning of optical surfaces, especially those of first-surface mirrors, is the most delicate and exacting task which the astronomer is called upon to perform. At the time of cleaning, a lens is most vulnerable to damage; damage which cannot be re paired. Yet if a telescope is to perform at its greatest potential, cleaning must be done time to time.

I have used the following method for over twenty-five years without adding a single scratch to the surface of my mirrors and lenses. It has the advantage of requiring only materials which are readily available at the neighborhood pharmacy or grocery store. The cost is less than twenty-five cents per cleaning.

First you must realize that usually the best advice on cleaning mirrors and lenses is.........DON'T DO IT. Dirt and grease which are adhering to the surface of mirrors and lenses may degrade image quality, but they will not damage the delicate optical surface until they are moved against it. Removing dirt without allowing it to rub against the underlying optical surface is what makes cleaning such a tricky task. If your mirrors and lenses are so dirty that they must be cleaned, then this is the way to do it:

FOR MIRRORS

Blow all loose dirt off with "Dust Off" or another canned clean air product. (Available in camera stores.) Take care not to shake the can while you are using it, and be sure to release a little air before using it on the optical surface. This will assure that no liquid is dispensed to make things worse! You can use a rubber bulb for this purpose, but it is not nearly as effective.
Prepare a VERY dilute solution of mild liquid detergent (e.g., Dawn). Use about 2 - 4 drops per liter (quart).
Rinse the mirror off under a moderate stream of luke-warm water for two or three minutes. Test the temperature of the water with your wrist, just as you would when warming a baby's bottle.
Make a number of cotton balls from a newly opened package of Johnson & Johnson sterile surgical cotton, U.S.P. Soak 2 or 3 balls in the detergent solution. Wipe the surface of the wet mirror with a circular motion, going first around the circumference, and then working your way towards the center. The only pressure on the cotton should be its own weight. For this first "wipe" you should use several fresh sets of cotton balls.
Throw cotton balls away.
Repeat process with new cotton balls, using a LITTLE more pressure.
Rinse mirror thoroughly under tap, which has been kept running for this step.
Rinse mirror with copious amounts of distilled water (do this no matter how clean or "hard" your tap water is).
Set mirror on edge to dry, using paper towels to absorb the water which will all run to bottom of mirror. Keep replacing the paper towels as the mirror dries.
If any beads of water do not run to bottom, blow them off with Dust Off, or the rubber bulb.
Replace the mirror in its cell, being careful to keep all clips and supports so loose that the mirror can rattle in the cell if it is shook. (Perhaps .5 to l mm clearance).
Spend the next month realigning your scope.
If you do anything more than this, you will damage the coating, and maybe the glass.
You should not have to clean an aluminized mirror more often than once per year. Do NOT over clean your optics.
FOR OBJECTIVE LENSES DO NOT UNDER ANY CIRCUMSTANCES REMOVE A LENS FROM ITS CELL, OR THE CELL FROM THE TELESCOPE.
This restriction means that the above procedure must be modified. Only the front surface can be cleaned. If you remove the cell from the telescope, you will be in big trouble. There are probably not more than 25 people in the United State s who can effectively collimate a refractor!

Blow loose dirt off with Dust-Off or a rubber bulb, using the above precautions.
Soak the cotton balls in a 50:50 solution of Windex (commercial glass cleaner containing ammonia) and water. Squeeze slightly so that the balls are not dripping wet.
Wipe front lens surfaces with the wet cotton, using only the pressure of the weight of the cotton balls. Follow immediately with dry cotton, using little or no pressure.
Repeat procedure, using slightly more pressure.
If some cotton lint remains on surface, blow off with Dust-Off or rubber bulb.
Repeat procedure if lens is not clean, but if one repeat does not do it give up and leave it as is.
Inspect lens to make sure that no cleaning solution has found its way into the lens cell, or between the elements. If this has happened, leave the telescope with the lens uncovered in a warm room until it is dry.
FOR EYEPIECES AND BARLOWS

Follow the procedure given for objective lenses, but use Q-Tips (cotton on plastic sticks) instead of cotton balls. You may, of course, clean both surfaces. The eyebrow juice on the eye lens of eyepieces may require repeated applications. I think that this is OK in this case.

SOME DON'TS

Do not use any aerosol spray product, no matter who sells it, or what their claims are.
Do not use lens tissue or paper. It DOES scratch.
Do not use pre-packaged cotton balls, they frequently are not cotton.
Do not use any kind of alcohol, especially on aluminized surfaces.
Do not use plain water.
Do not use any lens cleaning solution marketed by funny companies, like Focal, Jason, or Swift. Dawn and Windex (or their equivalents in other countries) are cheap and commonly available. HOW TO CLEAN MIRRORS AND LENSES
by Lenny Abbey, <LAbbeymindspring.com>

The cleaning of optical surfaces, especially those of first-surface mirrors, is the most delicate and exacting task which the astronomer is called upon to perform. At the time of cleaning, a lens is most vulnerable to damage; damage which cannot be re paired. Yet if a telescope is to perform at its greatest potential, cleaning must be done time to time.

I have used the following method for over twenty-five years without adding a single scratch to the surface of my mirrors and lenses. It has the advantage of requiring only materials which are readily available at the neighborhood pharmacy or grocery store. The cost is less than twenty-five cents per cleaning.

First you must realize that usually the best advice on cleaning mirrors and lenses is.........DON'T DO IT. Dirt and grease which are adhering to the surface of mirrors and lenses may degrade image quality, but they will not damage the delicate optical surface until they are moved against it. Removing dirt without allowing it to rub against the underlying optical surface is what makes cleaning such a tricky task. If your mirrors and lenses are so dirty that they must be cleaned, then this is the way to do it:

FOR MIRRORS

Blow all loose dirt off with "Dust Off" or another canned clean air product. (Available in camera stores.) Take care not to shake the can while you are using it, and be sure to release a little air before using it on the optical surface. This will assure that no liquid is dispensed to make things worse! You can use a rubber bulb for this purpose, but it is not nearly as effective.
Prepare a VERY dilute solution of mild liquid detergent (e.g., Dawn). Use about 2 - 4 drops per liter (quart).
Rinse the mirror off under a moderate stream of luke-warm water for two or three minutes. Test the temperature of the water with your wrist, just as you would when warming a baby's bottle.
Make a number of cotton balls from a newly opened package of Johnson & Johnson sterile surgical cotton, U.S.P. Soak 2 or 3 balls in the detergent solution. Wipe the surface of the wet mirror with a circular motion, going first around the circumference, and then working your way towards the center. The only pressure on the cotton should be its own weight. For this first "wipe" you should use several fresh sets of cotton balls.
Throw cotton balls away.
Repeat process with new cotton balls, using a LITTLE more pressure.
Rinse mirror thoroughly under tap, which has been kept running for this step.
Rinse mirror with copious amounts of distilled water (do this no matter how clean or "hard" your tap water is).
Set mirror on edge to dry, using paper towels to absorb the water which will all run to bottom of mirror. Keep replacing the paper towels as the mirror dries.
If any beads of water do not run to bottom, blow them off with Dust Off, or the rubber bulb.
Replace the mirror in its cell, being careful to keep all clips and supports so loose that the mirror can rattle in the cell if it is shook. (Perhaps .5 to l mm clearance).
Spend the next month realigning your scope.
If you do anything more than this, you will damage the coating, and maybe the glass.
You should not have to clean an aluminized mirror more often than once per year. Do NOT over clean your optics.
FOR OBJECTIVE LENSES DO NOT UNDER ANY CIRCUMSTANCES REMOVE A LENS FROM ITS CELL, OR THE CELL FROM THE TELESCOPE.
This restriction means that the above procedure must be modified. Only the front surface can be cleaned. If you remove the cell from the telescope, you will be in big trouble. There are probably not more than 25 people in the United State s who can effectively collimate a refractor!

Blow loose dirt off with Dust-Off or a rubber bulb, using the above precautions.
Soak the cotton balls in a 50:50 solution of Windex (commercial glass cleaner containing ammonia) and water. Squeeze slightly so that the balls are not dripping wet.
Wipe front lens surfaces with the wet cotton, using only the pressure of the weight of the cotton balls. Follow immediately with dry cotton, using little or no pressure.
Repeat procedure, using slightly more pressure.
If some cotton lint remains on surface, blow off with Dust-Off or rubber bulb.
Repeat procedure if lens is not clean, but if one repeat does not do it give up and leave it as is.
Inspect lens to make sure that no cleaning solution has found its way into the lens cell, or between the elements. If this has happened, leave the telescope with the lens uncovered in a warm room until it is dry.
FOR EYEPIECES AND BARLOWS

Follow the procedure given for objective lenses, but use Q-Tips (cotton on plastic sticks) instead of cotton balls. You may, of course, clean both surfaces. The eyebrow juice on the eye lens of eyepieces may require repeated applications. I think that this is OK in this case.

SOME DON'TS

Do not use any aerosol spray product, no matter who sells it, or what their claims are.
Do not use lens tissue or paper. It DOES scratch.
Do not use pre-packaged cotton balls, they frequently are not cotton.
Do not use any kind of alcohol, especially on aluminized surfaces.
Do not use plain water.
Do not use any lens cleaning solution marketed by funny companies, like Focal, Jason, or Swift. Dawn and Windex (or their equivalents in other countries) are cheap and commonly available.
 
  • #11
70
0
Wow, thanks for the post. I think I will print it off for reference.

Although, I am not a big fan of touching anything with an aluminumized coating such as secondary or primary mirrors.
I have done it with success, but at the same time very nervous of the procedure.
I know a couple of others that have not been diligent and ended up re coating.

Eyepieces I don't find a big deal if one is careful.
 

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