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Refractor Anti Reflection Coating longevity.

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#26 Sean Cunneen

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Posted 22 February 2013 - 06:15 PM

Certainly the quality of the coating has everything to do with it's longevity, but to give you an example, I have a Brandon Objective from maybe 1946 which has MGF2 coatings in beautiful condition. So when applied correctly and taken care of properly, coatings can last a LONG time.

#27 azure1961p

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Posted 22 February 2013 - 11:46 PM

I've frankly never heard if refractors *givn it up* like mirror coatings . The ONLY time I've heard if refractors losing coating effectiveness is abrasive contaminants, ammonia , ie; windex and finally dew laden with salt from the sea or outright ocean spray.

Typically tho aside from that - I think they outlast the observer no?

Pete

#28 Plane_Guru

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Posted 23 February 2013 - 10:17 AM

Hi Paul G

Would you be able to inform what what would be used instead of Magnesium Fluoride for ED glass elements?

#29 jrbarnett

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Posted 23 February 2013 - 10:25 AM

True, Pete, and with the exception of the FS-series from Tak, where the coatings on the front fluorite element protect the soft, reactive lens material from environmental or physical damage, failed refractor coatings have minimal impact on the performance of the instrument. I have four or five uncoated refractors that nonetheless perform like champs. Coatings don't fail catastrophically, so a coated objective with coating issues would be only partially uncoated. That would have even less of a detectable impact than having no coatings at all.

Telescopes are tools, and outside tools to boot. Maintaining them and not misusing them is sensible. Obsessing over having them not change in condition at all through time under ordinary use is not. That is better suited to the art collector. Worry about your Vermeer not degrading through the decades, not your Celestron. :grin:

Regards,

Jim

#30 Plane_Guru

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Posted 23 February 2013 - 10:30 AM

Hi Paul,

Would you be able to inform what what would be used instead of Magnesium Fluoride for ED glass elements?

#31 Plane_Guru

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Posted 23 February 2013 - 10:39 AM

Interesting input.I already stated that I love Science and have a keen interest in the Science of Optics.Thanks

#32 jrbarnett

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Posted 23 February 2013 - 10:51 AM

You may find this informative on mating coating formulations to glass type:

http://tech.groups.y...g/message/17280

"For best results of minimum reflectivity, each glass type should have its own
multi-layer formula. This can be expensive, and does impact the final cost in
things like multi-element eyepieces where there may be many different glass
types in each assembly. It is usually cheaper for the manufacturer to coat them
all with the same formula in a large batch. The end result is multi-colored
hues on the various surfaces."

Though it doesn't give you the actual chemical formulation of different coatings that are used for different glass types, it does indicate that different glass types benefit from different coating formulations. This is one of the high-cost features of the ZAO II Orthos - each air to glass surface has multicoatings optimized for the underlying glass type. Almost no one bothers to do this. I don't think that even A-P uses different coating formulations on different surfaces in its refractors.

Now Celestron does share what multicoatings it uses on its SCT corrector plates in this article:

http://www.celestron...starbright-xlt/

The correctors are water white glass. Celestron's AR coating on the correctors is a combination of MgF2 and HfO2 (Hafnium Dioxide).

Regards,

Jim

#33 TG

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Posted 24 February 2013 - 12:12 PM

I've frankly never heard if refractors *givn it up* like mirror coatings . The ONLY time I've heard if refractors losing coating effectiveness is abrasive contaminants, ammonia , ie; windex and finally dew laden with salt from the sea or outright ocean spray.

Typically tho aside from that - I think they outlast the observer no?

Pete


Windex does not contain ammonia:

http://www.aossmedic...lasscleaner.pdf

It's actually quite safe on lens coatings.


Tanveer

#34 mgwhittle

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Posted 24 February 2013 - 12:23 PM

Most windex products do contain ammonia.

From Windex website:

All but two Windex® Glass and Multi-Surface Cleaners contain detergents, solvents, fragrance, Ammonia-D®, and alcohol. They should not be used if ammonia is not recommended for use on surface. (Windex® Multi-Surface Vinegar and Windex® Outdoor Multi-Surface do not contain ammonia. They are safe to use in these cases.)

MSDS on Windex Ammonia D : http://www.btps.ca/f...x_Ammonia-D.pdf

Notice there is no mention of "ammonia" in the ingrediants. MSDS are not required to list any component in which there is less than 1% of a hazardous component in the mixture. Ammonia is in there, it's just not a required listing in the MSDS.

#35 TG

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Posted 24 February 2013 - 10:34 PM

Most windex products do contain ammonia.

From Windex website:

All but two Windex® Glass and Multi-Surface Cleaners contain detergents, solvents, fragrance, Ammonia-D®, and alcohol. They should not be used if ammonia is not recommended for use on surface. (Windex® Multi-Surface Vinegar and Windex® Outdoor Multi-Surface do not contain ammonia. They are safe to use in these cases.)

MSDS on Windex Ammonia D : http://www.btps.ca/f...x_Ammonia-D.pdf

Notice there is no mention of "ammonia" in the ingrediants. MSDS are not required to list any component in which there is less than 1% of a hazardous component in the mixture. Ammonia is in there, it's just not a required listing in the MSDS.


Do you have a source for confirming that there is actually ammonia in there? From what I recall, Ammonia-D is not actually ammonia but marketingspeak for some other chemical.

Tanveer

#36 teelgul

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Posted 25 February 2013 - 12:20 AM

Televue is a great scope optically and mechanically .
its only weak points if at all are its internal coating and its non airline portability . Its mechanical design is a mixture of old and traditional, but solid. But I dont believe that it can do things which no other 4 inch can do.
if we are a bit flexible with the 4 inch definition then TEC 110 will be way ahead in design,and portability with the same optical performance if not better.
Any way if you live in CON USA internal coatings should not be a worry as its a shorter distance to the Televue factory.
For me the coating peeeling off in 4 places with in three months in the not so humid sydney was a bad experience.
if i were a Televue owner i would be more concerned with the paper coating and a some times loose rack mechanism than with the lens coating which iam sure will outlive all of us. This is from first hand experience of two televue scopes.Hope Televue has a better resin and if the paper coating now is half as durable as their lens coating it will be fine for a life time . :D

#37 Plane_Guru

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Posted 25 February 2013 - 02:27 AM

Hello teelgul ,

I reside in Queensland,Eastern Australia and I am also worried about the Televue NP-101 Internal Flocking Paper lifespan and durability because where I reside the Weather can also be very humid(Central Queensland).

I have a brand NEW Televue NP-101 on order from:

http://www.bintel.co...roductview.aspx



I phoned The Binocular and Telescope Shop and raised the issue of the Internal Flocking Paper de-flocking and I was told that Televue have changed their Adhesives now to try and combat this very rare? issue.

All my best

#38 teelgul

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Posted 25 February 2013 - 04:47 AM

Hello guru
Televue did fix it up for me but i had to pay one way fare.
If the new resin has fixed it up then great. Televue should have done this long
Back .A slight debonding may not performance but it should not happen in a scope of this price range. . Any way if you are going to use it from a fixed location with occasional transport then it should be fine .
Cheers

#39 Plane_Guru

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Posted 25 February 2013 - 05:24 AM

Hello guru
Televue did fix it up for me but i had to pay one way fare.
If the new resin has fixed it up then great. Televue should have done this long
Back .A slight debonding may not performance but it should not happen in a scope of this price range. . Any way if you are going to use it from a fixed location with occasional transport then it should be fine .
Cheers



Hi ,I concur wholeheartedly..The Flocking paper De-Flocking and becoming unglued should never be an issue in a Premium Telescope of this price .I too hope that Televue's change to a new Adhesive/Resin fixes the De-Flocking issue.

#40 mgwhittle

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Posted 25 February 2013 - 08:49 AM

Most windex products do contain ammonia.

From Windex website:

All but two Windex® Glass and Multi-Surface Cleaners contain detergents, solvents, fragrance, Ammonia-D®, and alcohol. They should not be used if ammonia is not recommended for use on surface. (Windex® Multi-Surface Vinegar and Windex® Outdoor Multi-Surface do not contain ammonia. They are safe to use in these cases.)

MSDS on Windex Ammonia D : http://www.btps.ca/f...x_Ammonia-D.pdf

Notice there is no mention of "ammonia" in the ingrediants. MSDS are not required to list any component in which there is less than 1% of a hazardous component in the mixture. Ammonia is in there, it's just not a required listing in the MSDS.


Do you have a source for confirming that there is actually ammonia in there? From what I recall, Ammonia-D is not actually ammonia but marketingspeak for some other chemical.

Tanveer


Hi Tanveer, the quote above is directly from Windex's website regarding ammonia in their products. As you see they say specifically, except for two products, all their glass cleaners contain ammonia.

Here are all the ingredients in Windex with Ammonia D:
http://www.whatsinsi...x-1/windex-w...

And the contents of original Windex (the stuff often recommended here):
http://www.whatsinsi...x-1/windex-o...

Ammonium Hydroxide is listed in both.

I used the MSDS from Ammonia-D as an example that some ingredients are not listed on the MSDS even though they are in there. Ammonia-D is a trademarked marketing name and it is a 28% solution of ammonia present at .05% in their cleaners. Since it is only at .05% it is not required to be listed on the MSDS. You can gleen this information from the Windex website (http://www.windex.co.../Pages/Faq.aspx ), and how to read an MSDS (many sites, this just happened to come up first on a google search http://www.ehso.com/...regulations.php )

#41 jrbarnett

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Posted 25 February 2013 - 10:29 AM

I've seen few Televue refractors, including recent vintage units, on which you could see at least a bubble or two and/or the seam in the tube flocking material. Most never come loose, but some do. On Astromart you will see pictures from time to time of Televue objectives with the corner of the flocking material drooping into the tube. It happens.

That said, it shouldn't be a big deal as Televue will repair the issue in the unlikely event that that it arises. It's a risk (decontacted flocking) assumed to achieve the tube diameter goals (smaller due to the lack of knife edge baffles). In all things there are tradeoffs. Talahashi paint, for example, is beautiful but thin and fragile as a coating of toothpaste. Televue tube paint is bombproof by comparison. In all things there are tradeoffs. No one is charging enough for any of these scopes to be able to deliver perfection in every case. That's why we have warranties.

Regards,

Jim

#42 teelgul

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Posted 25 February 2013 - 12:57 PM

Hello guru
Just make sure about warranty in case .I did not get worried much about the issue And got upset only when televue initially advised me that it was due to humidity and not normally warrantied .

#43 TG

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Posted 25 February 2013 - 04:20 PM

Most windex products do contain ammonia.

From Windex website:

All but two Windex® Glass and Multi-Surface Cleaners contain detergents, solvents, fragrance, Ammonia-D®, and alcohol. They should not be used if ammonia is not recommended for use on surface. (Windex® Multi-Surface Vinegar and Windex® Outdoor Multi-Surface do not contain ammonia. They are safe to use in these cases.)

MSDS on Windex Ammonia D : http://www.btps.ca/f...x_Ammonia-D.pdf

Notice there is no mention of "ammonia" in the ingrediants. MSDS are not required to list any component in which there is less than 1% of a hazardous component in the mixture. Ammonia is in there, it's just not a required listing in the MSDS.


Do you have a source for confirming that there is actually ammonia in there? From what I recall, Ammonia-D is not actually ammonia but marketingspeak for some other chemical.

Tanveer


Hi Tanveer, the quote above is directly from Windex's website regarding ammonia in their products. As you see they say specifically, except for two products, all their glass cleaners contain ammonia.

Here are all the ingredients in Windex with Ammonia D:
http://www.whatsinsi...x-1/windex-w...

And the contents of original Windex (the stuff often recommended here):
http://www.whatsinsi...x-1/windex-o...

Ammonium Hydroxide is listed in both.

I used the MSDS from Ammonia-D as an example that some ingredients are not listed on the MSDS even though they are in there. Ammonia-D is a trademarked marketing name and it is a 28% solution of ammonia present at .05% in their cleaners. Since it is only at .05% it is not required to be listed on the MSDS. You can gleen this information from the Windex website (http://www.windex.co.../Pages/Faq.aspx ), and how to read an MSDS (many sites, this just happened to come up first on a google search http://www.ehso.com/...regulations.php )


Thanks, this is interesting reading. However, with a pH of 10.4, I don't think that Windex is going to strip any fluoride coatings off any time soon.

Tanveer.

#44 mgwhittle

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Posted 25 February 2013 - 04:52 PM

I completely agree with you. I have used Windex, along with other products (ROR, isopropyl alcohol and acetone) for years and will continue to do so.






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