To clean the primary mirror, or not to clean... that is the question

I recently acquired a second hand AG Optical FA12 Convergent (12.5", f/5, FL 1570). I am not sure how it typically performs when it is brand new and squeaky clean, so I don't have any data to measure actual performance degradation. Unfortunately I committed the ultimate sin of flashing a light at the primary mirror and corrector lens. Not sure if what I am seeing is just dust, or there is mold and pollen on it.

Here is what the primary mirror looks like:

I did have first light with this OTA. Here is what an autostretch flat looks like (6200mm pro, 50mm unmounted Ha filter):

I know this might not tell you much, but here is my first fully post processed image after 4 hours of integration fwiw:

What do you think? Should I attempt cleaning the primary? I am fairly confident I can do it safely, following this video that was done based on advice from the manufacturer but obviously it is something I would rather not do unless I absolutely have to.

https://youtu.be/jqkhmJxmbHQ?si=Il4R-t-H4fltjyL0

Interesting results so far! Everyone thinks I should leave the mirror alone. One thinks never touch it, and 5 have so far thought that I don't need to clean it now, but maybe later.

To those people that said clean it later, at what point do you clean the primary mirror? Is there a way to judge it by your light frames? Or are there any other indications when you directly visualize the mirror that suggests you should go ahead and clean it?

Look at the mirror in daylight but not under direct sunlight. If you can't see your face reflected in the main mirror that well (that is the image look very dull indeed) then is time to give the mirror a wash. If you can reasonably think to put everything back together and make the operation as scratch-less as possible. Plenty of distilled water and a high power hair dryer @ zero heating setting are your best friends.

andrea tasselli:
Look at the mirror in daylight but not under direct sunlight. If you can't see your face reflected in the main mirror that well (that is the image look very dull indeed) then is time to give the mirror a wash. If you can reasonably think to put everything back together and make the operation as scratch-less as possible. Plenty of distilled water and a high power hair dryer @ zero heating setting are your best friends.

That's great advice. I will give that a shot and post an image of the mirror in indirect sunlight and see what everyone thinks.

I clean the front lens of my refractor once a year, except if a bird is too precised and impolite…

My zenithstar 73 stays mounted now outside on its "astrobox".

Marc V:
I clean the front lens of my refractor once a year, except if a bird is too precised and impolite...

My zenithstar 73 stays mounted now outside on its "astrobox".

I do the same with my refractors. With open reflectors I find the decision to remove the mirror and clean it a difficult one.

Not familiar with particular model, but I know my iDK has optics from Ostahowski. Maybe reach out to them for guidance or even reach out to Dave Tandy (AG Optical founder).

I follow the mantra of if i have to ask whether the mirror needs cleaning it most certainly does not.

But since you mention the possibility of mold and pollen, its a different matter. That could attack and degrade the mirror coatings, which will end up as a significant issue later on, so in this case i think i would clean the mirror. But like always, be cautious when handling the mirror. You can clean a dirty mirror but you cant un-scratch a scratched mirror if you handle it too roughly.

Jeffery Richards:
Not familiar with particular model, but I know my iDK has optics from Ostahowski. Maybe reach out to them for guidance or even reach out to Dave Tandy (AG Optical founder).

I have reached out to Dave and I am awaiting a response. I didn't think to reach out to Ostahowski. That's a good idea. Thanks!

Oskari Nikkinen:
I follow the mantra of if i have to ask whether the mirror needs cleaning it most certainly does not.

But since you mention the possibility of mold and pollen, its a different matter. That could attack and degrade the mirror coatings, which will end up as a significant issue later on, so in this case i think i would clean the mirror. But like always, be cautious when handling the mirror. You can clean a dirty mirror but you cant un-scratch a scratched mirror if you handle it too roughly.

Thanks. I am no expert in pollens and mold. If I direct your attention to the picture, what do you think of all the "white diffuse" spots that are all over the mirror? Is this just dust or is it mold?

Hi Ashraf,
Firstly, I hope the ADC is working out for you. Now, as far as that mirror, yes, from the look of it, I would definitely - and very carefully - clean it. Many years ago, I cleaned the primary of a 12.5" RC that had collected pollen from a nearby Russian Olive tree. I had been advised against it, but the accumulation was so much. I have also cleaned the two objectives of a classic 20" Clark refractor, with wonderful results.

Obviously, once it's cleaned, then protecting it from a large amount of further collection would be fine, and would require only periodic attention with canned air, which I do to my front corrector every month or so.

As many have mentioned, carefully blow off any hard particulates. If the mirror is removable, lay it in a clean sink and fill the sink with warm water, not hot. If the mirror is not removable, much of the following procedure can be accomplished with the mirror propped up.

Add a few drops of Dawn dishwashing liquid, swirl the water/detergent mixture with a rubber-gloved hand, then allow the mirror to sit in the liquid for about an hour.

After the hour, take a handful of sterile cotton balls, and very-gently wipe in a circular motion over the mirror, then wait a few minutes, and repeat. The mirror can then be rinsed with regular tap water, and then removed to a place where it can be stood upright. At this point, no more rubbing is necessary. You'll then want to rinse the mirror, from the top down, with distilled water, and allow it to air-dry. Anything left on the mirror would probably require more intense rubbing, and this is not recommended for fear of damaging the surface. However, if any remaining stain requires attention, carefully apply 90% Isopropyl alcohol to a sterile microfiber cloth and gently rub; if the stain remains, leave it alone - a flat frame will notice it and cancel it out in processing.

The distilled water rinse should not leave any spots, but any remaining can be removed with the alcohol/microfiber cloth application.

Best of luck. After cleaning the 12.5", there was a noticeable result in images.

- - Steve

Ashraf AbuSara:
Thanks. I am no expert in pollens and mold. If I direct your attention to the picture, what do you think of all the "white diffuse" spots that are all over the mirror? Is this just dust or is it mold?

*Best described as condensed dust, that is concentrated by dew. My primary looks the same after 2 years in the open, maybe a tad worse if I shine a light on it. Never do that.

andrea tasselli:
Ashraf AbuSara:
Thanks. I am no expert in pollens and mold. If I direct your attention to the picture, what do you think of all the "white diffuse" spots that are all over the mirror? Is this just dust or is it mold?

*Best described as condensed dust, that is concentrated by dew. My primary looks the same after 2 years in the open, maybe a tad worse if I shine a light on it. Never do that.

Agreed. It was the ultimate sin as I said in the original post. What happened really is I had my head lamp on, and I was looking down the scope barrel to remove the dust cap and dust smilled back at me and triggered my OCD.

Steve Solon:
Hi Ashraf,
Firstly, I hope the ADC is working out for you. Now, as far as that mirror, yes, from the look of it, I would definitely - and very carefully - clean it. Many years ago, I cleaned the primary of a 12.5" RC that had collected pollen from a nearby Russian Olive tree. I had been advised against it, but the accumulation was so much. I have also cleaned the two objectives of a classic 20" Clark refractor, with wonderful results.

Obviously, once it's cleaned, then protecting it from a large amount of further collection would be fine, and would require only periodic attention with canned air, which I do to my front corrector every month or so.

As many have mentioned, carefully blow off any hard particulates. If the mirror is removable, lay it in a clean sink and fill the sink with warm water, not hot. If the mirror is not removable, much of the following procedure can be accomplished with the mirror propped up.

Add a few drops of Dawn dishwashing liquid, swirl the water/detergent mixture with a rubber-gloved hand, then allow the mirror to sit in the liquid for about an hour.

After the hour, take a handful of sterile cotton balls, and very-gently wipe in a circular motion over the mirror, then wait a few minutes, and repeat. The mirror can then be rinsed with regular tap water, and then removed to a place where it can be stood upright. At this point, no more rubbing is necessary. You'll then want to rinse the mirror, from the top down, with distilled water, and allow it to air-dry. Anything left on the mirror would probably require more intense rubbing, and this is not recommended for fear of damaging the surface. However, if any remaining stain requires attention, carefully apply 90% Isopropyl alcohol to a sterile microfiber cloth and gently rub; if the stain remains, leave it alone - a flat frame will notice it and cancel it out in processing.

The distilled water rinse should not leave any spots, but any remaining can be removed with the alcohol/microfiber cloth application.

Best of luck. After cleaning the 12.5", there was a noticeable result in images.

- - Steve

Thank you for the detailed reply!

I was hoping that I can clean it by simply taking detaching the backplate with the mirror still mounted on it, to somewhat preserve the collimation a bit and avoid having to start from scratch.

Thanks for the great advice. If I decide to clean it I will keep everyone posted!

Ashraf

Ashraf AbuSara:
Agreed. It was the ultimate sin as I said in the original post. What happened really is I had my head lamp on, and I was looking down the scope barrel to remove the dust cap and dust smilled back at me and triggered my OCD.

OCD is such a terrible disease. I know the feeling...

Ashraf AbuSara:
Steve Solon:
Hi Ashraf,
Firstly, I hope the ADC is working out for you. Now, as far as that mirror, yes, from the look of it, I would definitely - and very carefully - clean it. Many years ago, I cleaned the primary of a 12.5" RC that had collected pollen from a nearby Russian Olive tree. I had been advised against it, but the accumulation was so much. I have also cleaned the two objectives of a classic 20" Clark refractor, with wonderful results.

Obviously, once it's cleaned, then protecting it from a large amount of further collection would be fine, and would require only periodic attention with canned air, which I do to my front corrector every month or so.

As many have mentioned, carefully blow off any hard particulates. If the mirror is removable, lay it in a clean sink and fill the sink with warm water, not hot. If the mirror is not removable, much of the following procedure can be accomplished with the mirror propped up.

Add a few drops of Dawn dishwashing liquid, swirl the water/detergent mixture with a rubber-gloved hand, then allow the mirror to sit in the liquid for about an hour.

After the hour, take a handful of sterile cotton balls, and very-gently wipe in a circular motion over the mirror, then wait a few minutes, and repeat. The mirror can then be rinsed with regular tap water, and then removed to a place where it can be stood upright. At this point, no more rubbing is necessary. You'll then want to rinse the mirror, from the top down, with distilled water, and allow it to air-dry. Anything left on the mirror would probably require more intense rubbing, and this is not recommended for fear of damaging the surface. However, if any remaining stain requires attention, carefully apply 90% Isopropyl alcohol to a sterile microfiber cloth and gently rub; if the stain remains, leave it alone - a flat frame will notice it and cancel it out in processing.

The distilled water rinse should not leave any spots, but any remaining can be removed with the alcohol/microfiber cloth application.

Best of luck. After cleaning the 12.5", there was a noticeable result in images.

- - Steve

Thank you for the detailed reply!

I was hoping that I can clean it by simply taking detaching the backplate with the mirror still mounted on it, to somewhat preserve the collimation a bit and avoid having to start from scratch.

Thanks for the great advice. If I decide to clean it I will keep everyone posted!

Ashraf

I think there is a YouTube video showing just that.

Jeffery Richards:
Ashraf AbuSara:
Steve Solon:
Hi Ashraf,
Firstly, I hope the ADC is working out for you. Now, as far as that mirror, yes, from the look of it, I would definitely - and very carefully - clean it. Many years ago, I cleaned the primary of a 12.5" RC that had collected pollen from a nearby Russian Olive tree. I had been advised against it, but the accumulation was so much. I have also cleaned the two objectives of a classic 20" Clark refractor, with wonderful results.

Obviously, once it's cleaned, then protecting it from a large amount of further collection would be fine, and would require only periodic attention with canned air, which I do to my front corrector every month or so.

As many have mentioned, carefully blow off any hard particulates. If the mirror is removable, lay it in a clean sink and fill the sink with warm water, not hot. If the mirror is not removable, much of the following procedure can be accomplished with the mirror propped up.

Add a few drops of Dawn dishwashing liquid, swirl the water/detergent mixture with a rubber-gloved hand, then allow the mirror to sit in the liquid for about an hour.

After the hour, take a handful of sterile cotton balls, and very-gently wipe in a circular motion over the mirror, then wait a few minutes, and repeat. The mirror can then be rinsed with regular tap water, and then removed to a place where it can be stood upright. At this point, no more rubbing is necessary. You'll then want to rinse the mirror, from the top down, with distilled water, and allow it to air-dry. Anything left on the mirror would probably require more intense rubbing, and this is not recommended for fear of damaging the surface. However, if any remaining stain requires attention, carefully apply 90% Isopropyl alcohol to a sterile microfiber cloth and gently rub; if the stain remains, leave it alone - a flat frame will notice it and cancel it out in processing.

The distilled water rinse should not leave any spots, but any remaining can be removed with the alcohol/microfiber cloth application.

Best of luck. After cleaning the 12.5", there was a noticeable result in images.

- - Steve

Thank you for the detailed reply!

I was hoping that I can clean it by simply taking detaching the backplate with the mirror still mounted on it, to somewhat preserve the collimation a bit and avoid having to start from scratch.

Thanks for the great advice. If I decide to clean it I will keep everyone posted!

Ashraf

I think there is a YouTube video showing just that.

*Yes that's what I plan to follow once I decide to clean it. The question is if I should.

I'd warn everyone wanting to wash-clean their mirrors to not let air-dry the mirror. Even distilled water washing wont prevent leaving faint marks on the surface (thanks to dust mostly) but to blow dry the surface of the mirror with a high-power hair-dryer (or similar) set at no or minimum heating will achieve a perfectly dry and clean surface. You want to actually remove the water droplets by shear air force so that absolutely no water is left on the surface of the mirror.

Also, If a stubborn mark remains just leave it be, Don't rub, just pull the cotton ball across and drag but do not push. Even moderate pitting won't affect the performance of the mirror but sure as the day is bright scratching the surface will worsen it by a lot.

Ashraf AbuSara:
Jeffery Richards:
Not familiar with particular model, but I know my iDK has optics from Ostahowski. Maybe reach out to them for guidance or even reach out to Dave Tandy (AG Optical founder).

I have reached out to Dave and I am awaiting a response. I didn't think to reach out to Ostahowski. That's a good idea. Thanks!

Oskari Nikkinen:
I follow the mantra of if i have to ask whether the mirror needs cleaning it most certainly does not.

But since you mention the possibility of mold and pollen, its a different matter. That could attack and degrade the mirror coatings, which will end up as a significant issue later on, so in this case i think i would clean the mirror. But like always, be cautious when handling the mirror. You can clean a dirty mirror but you cant un-scratch a scratched mirror if you handle it too roughly.

Thanks. I am no expert in pollens and mold. If I direct your attention to the picture, what do you think of all the "white diffuse" spots that are all over the mirror? Is this just dust or is it mold?

Cant tell from just the image, could be just dust. Shining a light like this on a mirror will make minor and unimportant dust spots look bad so its not easy to tell. If you attempt to clean it and the gunk stays on the mirror after blowing air on it/slightly agitating it with something soft, then its something stuck on the mirror.

I image in Finland and at certain times of year there is a lot of pollen in the air, as well as moisture that could develop mold. Havent seen mold on my newtonian, but pollen i have. Its more sticky than simple dust and requires actual cleaning rather than just a slight air/camera cleaning brush treatment to get rid of.

Oskari Nikkinen:
Ashraf AbuSara:
Jeffery Richards:
Not familiar with particular model, but I know my iDK has optics from Ostahowski. Maybe reach out to them for guidance or even reach out to Dave Tandy (AG Optical founder).

I have reached out to Dave and I am awaiting a response. I didn't think to reach out to Ostahowski. That's a good idea. Thanks!

Oskari Nikkinen:
I follow the mantra of if i have to ask whether the mirror needs cleaning it most certainly does not.

But since you mention the possibility of mold and pollen, its a different matter. That could attack and degrade the mirror coatings, which will end up as a significant issue later on, so in this case i think i would clean the mirror. But like always, be cautious when handling the mirror. You can clean a dirty mirror but you cant un-scratch a scratched mirror if you handle it too roughly.

Thanks. I am no expert in pollens and mold. If I direct your attention to the picture, what do you think of all the "white diffuse" spots that are all over the mirror? Is this just dust or is it mold?

Cant tell from just the image, could be just dust. Shining a light like this on a mirror will make minor and unimportant dust spots look bad so its not easy to tell. If you attempt to clean it and the gunk stays on the mirror after blowing air on it/slightly agitating it with something soft, then its something stuck on the mirror.

I image in Finland and at certain times of year there is a lot of pollen in the air, as well as moisture that could develop mold. Havent seen mold on my newtonian, but pollen i have. Its more sticky than simple dust and requires actual cleaning rather than just a slight air/camera cleaning brush treatment to get rid of.

*Fair enough. I can't tell to be honest just by looking either.

Asking for the best way to clean optics is often a fast track to a food fight among amateurs so I'm happy to see a civil discussion here. I've cleaned a lot of optical surfaces and for over-coated mirrors like you'll find in most telescopes, it's not that hard. I've cleaned a lot of C14 scopes, my 20" Planewave and a few 24" mirrors. From what I see in your photo, the amount of grime on your mirror might not affect the image quality by very much but that's a lot of grime. I would definitely clean it just to improve the throughput, which is generally the biggest thing affected by dust and deposits on telescope mirrors.

Here is the method that I use:

1) Blow off loose debris with a high pressure air. Be careful to avoid using a compressor that might blow a mist of oil. The air has to be clean and dry.

2) Mix distilled water with 99.9% isopropyl alcohol about 1 part alcohol to 7 parts water in a new, clean spray bottle. You can order reagent grade 99.9% alcohol through Amazon. DO NOT use drugstore rubbing alcohol. Some super markets sell 99% alcohol, which is okay but I prefer reagent grade to minimize deposits. You can add 1-2 drop of dishwashing liquid per cup, which will reduce surface tension and help reduce potential spotting. If your water and alcohol are really pure, you won't get any significant spotting (as long as the surface is really clean as well).

3) Have a can of compress air and a box of Kleenex brand facial tissue on hand. Make sure that you don't use tissue that contain lotion or anything else. Just get pure tissue--Kleenex brand is the best. Kim Wipes are fine as well, but it's not worth any extra effort to get Kim Wipes if you don't already have them on hand. I wear thin Nitride gloves to keep skin oil off the tissue.

4) Start by spraying the surface and very gently blotting the surface in small patches. Take your time and turn or replace the tissue to always blot with a clean surface. Tissue is cheap. Blot the surface three times and grab a fresh piece. Keep spraying and blotting (not wiping) the surface until the tissues come up clean. Try to avoid having water wick or run under mounting components if possible.

5) Next, start soaking patches of the surface and with very light pressure, wipe up the dirt using a rolling motion with the tissue. Replace the tissue with a new piece with every wipe. You should be ankle deep in tissue by the time you have gently wiped the entire surface.

6) Finally lightly mist the surface and polish it with a clean tissue followed immediately with a puff of air to dry it to avoid spotting. Use a VERY bright flashlight to inspect the surface for any regions that show any film and polish those out with a very light mist and a dry tissue. The finished surface should look like new with a bright specular reflection.

Here are a couple of examples:

John

John Hayes:
Asking for the best way to clean optics is often a fast track to a food fight among amateurs so I'm happy to see a civil discussion here. I've cleaned a lot of optical surfaces and for over-coated mirrors like you'll find in most telescopes, it's not that hard. I've cleaned a lot of C14 scopes, my 20" Planewave and a few 24" mirrors. From what I see in your photo, the amount of grime on your mirror might not affect the image quality by very much but that's a lot of grime. I would definitely clean it just to improve the throughput, which is generally the biggest thing affected by dust and deposits on telescope mirrors.

Here is the method that I use:

1) Blow off loose debris with a high pressure air. Be careful to avoid using a compressor that might blow a mist of oil. The air has to be clean and dry.

2) Mix distilled water with 99.9% isopropyl alcohol about 1 part alcohol to 7 parts water in a new, clean spray bottle. You can order reagent grade 99.9% alcohol through Amazon. DO NOT use drugstore rubbing alcohol. Some super markets sell 99% alcohol, which is okay but I prefer reagent grade to minimize deposits. You can add 1-2 drop of dishwashing liquid per cup, which will reduce surface tension and help reduce potential spotting. If your water and alcohol are really pure, you won't get any significant spotting (as long as the surface is really clean as well).

3) Have a can of compress air and a box of Kleenex brand facial tissue on hand. Make sure that you don't use tissue that contain lotion or anything else. Just get pure tissue--Kleenex brand is the best. Kim Wipes are fine as well, but it's not worth any extra effort to get Kim Wipes if you don't already have them on hand. I wear thin Nitride gloves to keep skin oil off the tissue.

4) Start by spraying the surface and very gently blotting the surface in small patches. Take your time and turn or replace the tissue to always blot with a clean surface. Tissue is cheap. Blot the surface three times and grab a fresh piece. Keep spraying and blotting (not wiping) the surface until the tissues come up clean. Try to avoid having water wick or run under mounting components if possible.

5) Next, start soaking patches of the surface and with very light pressure, wipe up the dirt using a rolling motion with the tissue. Replace the tissue with a new piece with every wipe. You should be ankle deep in tissue by the time you have gently wiped the entire surface.

6) Finally lightly mist the surface and polish it with a clean tissue followed immediately with a puff of air to dry it to avoid spotting. Use a VERY bright flashlight to inspect the surface for any regions that show any film and polish those out with a very light mist and a dry tissue. The finished surface should look like new with a bright specular reflection.

Here are a couple of examples:

John

Thank you so much John for detailing your extensive experience in this regard. This is great!

I have decided I will clean the mirror in the next few weeks once I can dedicate time for that.

I might even try to do an anecdotal test by imaging a target for one hour before and after cleaning under similar conditions and see if it made a difference. Maybe that helps others decide if cleaning the primary in such a condition is worth it. Not expecting better details, but as you say better throughput and improved SNR.

I’ve made and owned newts for decades. Two important skills are collimation and mirror cleaning. Learn to collimate from scratch and never let collimation prevent you from cleaning the mirror.

I wash my mirrors once a year by blowing them off with a rocket blower and then spraying them with a solution of distilled water and drop if Dawn, finishing with just the distilled water.

For me, the key to good mirror maintenance is to avoid the trap of perfection. Trying to get a perfectly clean, spotless mirror is what gets many in trouble. I have mirrors that are over 20 years old with no pinholes even though I wash them each year.

Ashraf AbuSara:
I might even try to do an anecdotal test by imaging a target for one hour before and after cleaning under similar conditions and see if it made a difference. Maybe that helps others decide if cleaning the primary in such a condition is worth it. Not expecting better details, but as you say better throughput and improved SNR.

Ashraf,
That's a good idea. Throughput is the biggest thing affected by dirt on your optics but all that dirt can also scatter light, which can result in a slight increase in FWHM values. Be sure to check the condition of the secondary mirror and the field optics (if you can get at them). My 20" has a nice feature that allows unscrewing the primary mirror baffle to gain easy access to the field lenses for cleaning. The mag-fluoride overcoat on your mirrors is pretty hard so if you are reasonably careful, there isn't much danger of scratching the surface--and even if you do, it won't hurt the performance of your scope in any measurable way. Follow my procedure and your optics should remain scratch free and look brand new when you are done.

I should mention one other thing. Sometimes pollen and other contaminants can become pretty firmly glued to an optical surface--particularly if the optics get wet from dew. The water/alcohol mixture that I've recommended usually removes this stuff, but if it doesn't, don't be afraid to spot treat the mirror with 100% alcohol or even high purity acetone. The folks at Celestron normally clean all of their optics in production with 100% acetone but I now avoid recommending Acetone for general use. Acetone is a really good solvent but it has two undesirable properties. First, it will dissolve greasy material like oil or grease but it tends to mostly redistribute them as a film over the surface. Second, acetone breaks down cellulose so tissue and wipes start to come apart fairly quickly as you clean so use a new tissue for every wipe. You also have to be very careful about the type of gloves that you use. Acetone will dissolve rubber and other materials, which can get onto the optics. I now only recommend acetone as a last resort for really stubborn stains.

Good luck with it!

John

John Hayes:
Ashraf AbuSara:
I might even try to do an anecdotal test by imaging a target for one hour before and after cleaning under similar conditions and see if it made a difference. Maybe that helps others decide if cleaning the primary in such a condition is worth it. Not expecting better details, but as you say better throughput and improved SNR.

Ashraf,
That's a good idea. Throughput is the biggest thing affected by dirt on your optics but all that dirt can also scatter light, which can result in a slight increase in FWHM values. Be sure to check the condition of the secondary mirror and the field optics (if you can get at them). My 20" has a nice feature that allows unscrewing the primary mirror baffle to gain easy access to the field lenses for cleaning. The mag-fluoride overcoat on your mirrors is pretty hard so if you are reasonably careful, there isn't much danger of scratching the surface--and even if you do, it won't hurt the performance of your scope in any measurable way. Follow my procedure and your optics should remain scratch free and look brand new when you are done.

I should mention one other thing. Sometimes pollen and other contaminants can become pretty firmly glued to an optical surface--particularly if the optics get wet from dew. The water/alcohol mixture that I've recommended usually removes this stuff, but if it doesn't, don't be afraid to spot treat the mirror with 100% alcohol or even high purity acetone. The folks at Celestron normally clean all of their optics in production with 100% acetone but I now avoid recommending Acetone for general use. Acetone is a really good solvent but it has two undesirable properties. First, it will dissolve greasy material like oil or grease but it tends to mostly redistribute them as a film over the surface. Second, acetone breaks down cellulose so tissue and wipes start to come apart fairly quickly as you clean so use a new tissue for every wipe. You also have to be very careful about the type of gloves that you use. Acetone will dissolve rubber and other materials, which can get onto the optics. I now only recommend acetone as a last resort for really stubborn stains.

Good luck with it!

John

The AG optocical FA12 baffle also can easily be unscrewed to have access to the corrector lenses. They are pemenantly mounted / aligned, so I plan to just clean their surfaces with the Takahashi enzyme cleaning kit. Not looking for perfect, just less dust bunnies would be great.

As to the mirror I definitely am not looking for perfection as that is unlikely to be high yield. I just want to get rid of the majority of the grime pollen.

Thank you for the valuable information! I will report back here once I get it done.

CS!

Ashraf

Randy Roy:
I’ve made and owned newts for decades. Two important skills are collimation and mirror cleaning. Learn to collimate from scratch and never let collimation prevent you from cleaning the mirror.

I wash my mirrors once a year by blowing them off with a rocket blower and then spraying them with a solution of distilled water and drop if Dawn, finishing with just the distilled water.

For me, the key to good mirror maintenance is to avoid the trap of perfection. Trying to get a perfectly clean, spotless mirror is what gets many in trouble. I have mirrors that are over 20 years old with no pinholes even though I wash them each year.

Yes perfect is the enemy of good in my line of work too.

Should I clean the primary mirror