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Mirror aluminizing

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#1 zeddie

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Posted 28 September 2020 - 06:37 PM

Any opinions on where to get a mirror aluminized? OWL (Optic Wave Labs) will test the mirror for free. Anyone have any experience with them?

Thanks!



#2 Steve Dodds

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Posted 28 September 2020 - 06:44 PM

Any opinions on where to get a mirror aluminized? OWL (Optic Wave Labs) will test the mirror for free. Anyone have any experience with them?

Thanks!

They have their ups and downs.  Last couple of months they had a lot of returns, turns out they had an idiot running their system, they replaced him and since then things have been ok.


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#3 CltFlyboy

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Posted 30 September 2020 - 10:25 AM

Does anyone have a preferred/trusted shop for this work? I've got a secondary on my 10" SCT that has freckles and needs a strip/coat. Only the secondary, the primary is in pristine condition.



#4 DAVIDG

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Posted 30 September 2020 - 10:35 AM

Does anyone have a preferred/trusted shop for this work? I've got a secondary on my 10" SCT that has freckles and needs a strip/coat. Only the secondary, the primary is in pristine condition.

 Never had any issues with Majestic. I have been using them for years. They are also fast. Usually I get my optics back within a week while other companies it can be a month or more.

  https://www.majestic-coatings.com/

 

              - Dave 


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#5 Garyth64

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Posted 30 September 2020 - 10:38 AM

I have always used Majestic, never had a problem.

 

Here is a recent thread here on CN from a few weeks ago:

 

https://www.cloudyni...oating-choices/


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#6 zeddie

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Posted 30 September 2020 - 08:07 PM

They have their ups and downs.  Last couple of months they had a lot of returns, turns out they had an idiot running their system, they replaced him and since then things have been ok.

FYI, OWL no longer does mirror tests.



#7 JohnnyMonroe

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Posted 03 October 2020 - 11:23 PM

Don't do business with Optic Wave Labs. Search the forums for other threads about it.



#8 stargazer193857

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Posted 05 October 2020 - 09:57 AM

Has anyone done the tape test on coatings from any known coaters? I saw a youtube coater from some coater showing passed the duck tape test, and saying that military standards only mean passing the parafin test.

How important do you think these tests actually are for normal handling and soap water cleaning without scrubbing?

#9 Oregon-raybender

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Posted 05 October 2020 - 04:11 PM

The tape test is for military grade optics, only.  It was put into place during WW2 to assure the coating would last during the war and or storage for replacement. The tape used is cellophane type, (no other tape should be used, the glue is different, some is stronger than others) the edge is tested, never the clear aperture of the optic. The pull is slow.

 

The test was designed to test the cleaning method and adherence of the coating (glow discharge) 

 

I would not advise doing a tape test on amateur optics, unless you paid for a military grade coating (which is 2-3x more expensive)

 

Normal cleaning using soap and distilled water should not cause the coating to be remove regardless of the passing the tape test or not.

 

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#10 Steve Dodds

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Posted 05 October 2020 - 05:09 PM

Just FYI doing the tape test even if it doesn't peel off the aluminum, will peel off most of the overcoat.


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#11 zeddie

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Posted 06 October 2020 - 02:19 PM

Ok, so what about protected aluminum vs. enhanced aluminum (vs. Spectrum's "MaxR")? Opinions?



#12 Steve Dodds

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Posted 06 October 2020 - 03:26 PM

Ok, so what about protected aluminum vs. enhanced aluminum (vs. Spectrum's "MaxR")? Opinions?

Contrary to most opinions they will both last the same amount of time, and enhanced doesn't scatter light more than reg al., however you will never see any difference between them, Never! 5% just isn't enough to see visually, I know this because I tried it.


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#13 stargazer193857

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Posted 06 October 2020 - 03:45 PM

Even if 6% could be see between 2 mirrors, often secondaries are done with the primaries, and so might not have the optimal thicknesses for 45 degrees.

In the best case, a 10" with enhanced coatings would be as bright as a 96/89*10"= 10.8". It would be 16% brighter total between the two mirrors. 20% is considered the limit people notice.

But nothing wrong with paying to go a bit brighter if you can. It could matter on some threshold objects, but not be noticed on others.

The 20% line in the sand really just is based on how many objects will have a difference at different magnifications. Probably at least one will be on the edge.

#14 stargazer193857

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Posted 06 October 2020 - 03:50 PM

I had an 8" and a 6", both at 53x, aimed at M51. Not much difference. I could tell the 8" was brighter, indeed twice as bright. But it did not make much difference in the beauty or what I could see.

I aimed a 10" and 35mm eyepiece at M13 (34x), and a 6" at 53x. Side by side. I saw a better view in the 6". Magnification matters.


But then I took that 10" up to 208x, and same with the 8". The 10" then blew away the 8". One was dim, the other bright.

Aperture matters most at high power or on dim dust lanes. Not much difference on bright stuff at 3-4mm exit pupil.

Your eyes may vary.



All 3 scopes were set up next to each other. I wish I could have seen M31 in the 10", but it went behind a tree. I did not feel like tree dodging with it, and only saw M31 in the 8" and 6".

Edited by stargazer193857, 06 October 2020 - 03:53 PM.


#15 Steve Dodds

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Posted 06 October 2020 - 04:25 PM

Even if 6% could be see between 2 mirrors, often secondaries are done with the primaries, and so might not have the optimal thicknesses for 45 degrees.

In the best case, a 10" with enhanced coatings would be as bright as a 96/89*10"= 10.8". It would be 16% brighter total between the two mirrors. 20% is considered the limit people notice.

But nothing wrong with paying to go a bit brighter if you can. It could matter on some threshold objects, but not be noticed on others.

The 20% line in the sand really just is based on how many objects will have a difference at different magnifications. Probably at least one will be on the edge.

The reason I say there is no difference is, back in 2000 Tom Clark of Tectron telescopes took 2  20" f/5 scopes to the winter star party.  One scope had enhanced on both mirrors, the other had regular aluminum on both mirrors.  With both scopes on the same object, same eyepiece, same observer, all night not one person could tell the difference.  And if these people under the best skies in the country couldn't tell, you can't either.


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