I recently aquired an old celestron comet catcher for use as a super finder on the big scope that I am building. After a few minor repairs, it works very well. My only quam is that the corrector plate is uncoated. Is there anywhere quasi-local where I could get at least a magnesium flouride coating put on it? Greg --------------------------------- Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day
Greg, for a finder you won't notice any difference re: coated vs. uncoated. -BUT- The last time I got new eyeglasses, anti-reflection coatings were offered as an option. I use glass lenses exclusively, prescription safety glasses, essentially. So I"m pretty sure that there are local labs who can do it. C. --- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
I recently aquired an old celestron comet catcher for use as a super finder on the big scope that I am building. After a few minor repairs, it works very well. My only quam is that the corrector plate is uncoated. Is there anywhere quasi-local where I could get at least a magnesium flouride coating put on it?
Greg
--------------------------------- Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Thanks. The reason that I was asking is that when I was testing it out on Jupiter this morning, the light from the moon reflected off of the plate, causing the field to be washed-out. (I'm somewhat astonished at how razor thin the focal plane is at f/3.64). Greg Chuck Hards <chuckhards@yahoo.com> wrote:Greg, for a finder you won't notice any difference re: coated vs. uncoated. -BUT- The last time I got new eyeglasses, anti-reflection coatings were offered as an option. I use glass lenses exclusively, prescription safety glasses, essentially. So I"m pretty sure that there are local labs who can do it. C. --- Greg Taylor wrote:
I recently aquired an old celestron comet catcher for use as a super finder on the big scope that I am building. After a few minor repairs, it works very well. My only quam is that the corrector plate is uncoated. Is there anywhere quasi-local where I could get at least a magnesium flouride coating put on it?
Greg
--------------------------------- Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy --------------------------------- Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day
As I recall, this thing has no dewcap or glare shield, right? You could make a dewcap about twice the aperture in length. This would serve to keep the corrector from dewing-up, and let you spot targets close to the moon with less glare. Also, an anti-reflection coating can be done at home- it's not an evaporated coating, but a chemical surface etch. It has been in S&T and at least one other ATM-type journal, but memory fails me right now on the specifics. Chuck --- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Thanks. The reason that I was asking is that when I was testing it out on Jupiter this morning, the light from the moon reflected off of the plate, causing the field to be washed-out. (I'm somewhat astonished at how razor thin the focal plane is at f/3.64). Greg
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
I just searched the archives of S&T, and I can't find anything about making one's one coatings. I also searched the web, no dice. Do you have an aproximate time range of when you saw the articles? Greg --- Chuck Hards <chuckhards@yahoo.com> wrote:
As I recall, this thing has no dewcap or glare shield, right? You could make a dewcap about twice the aperture in length. This would serve to keep the corrector from dewing-up, and let you spot targets close to the moon with less glare.
Also, an anti-reflection coating can be done at home- it's not an evaporated coating, but a chemical surface etch. It has been in S&T and at least one other ATM-type journal, but memory fails me right now on the specifics.
Chuck
--- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Thanks. The reason that I was asking is that when I was testing it out on Jupiter this morning, the light from the moon reflected off of the plate, causing the field to be washed-out. (I'm somewhat
astonished
at how razor thin the focal plane is at f/3.64). Greg
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Well, I've been reading S&T since the early seventies, it could have been anytime in the last 30 years, but for some reason I'm thinking late 70's to mid 80's. You may need to search the cumulative index, I think the on-line archives only go back 15 years or so, last time I checked. As time permits, I'll go through my collection and let you know if I find the article. There is a short section on vacuum-deposition of coatings in ATM 3, page 337, but it has little to no practical advice. Chuck --- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
I just searched the archives of S&T, and I can't find anything about making one's one coatings. I also searched the web, no dice. Do you have an aproximate time range of when you saw the articles?
Greg
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Just checking the S&T archives, they DO now go back to the first issue. I found 567 articles using "lens coatings" as search terms....this is going to take some time. C.
--- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
I just searched the archives of S&T, and I can't find anything about making one's one coatings. I also searched the web, no dice. Do you have an aproximate time range of when you saw the articles?
Greg
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
I've tried searching S&T from my work computer, which is considerabley faster. No luck. Obviously the search terms I'm using are not in the article title. The farther back you go in the archives, fewer keywords are available to the search engine. I'll have to go through my collection by hand; I am positive they published an article on coating lenses at home, though it may have been a side-bar for a different subject, in which case the search engine may not find it all. I'll also check with my contacts at S&T directly. C. __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Now I see that the fault is with the selectivity of the S&T search engine. A search using "eyepeice" with various modifiers failed to turn-up even one of my own articles, Feb. 00, on home-made eyepieces! Here again is demonstrated one of the failings of Web searches; sometimes only an exact search term will get you what you want. I'm still a firm believer in the superiority of good old fashioned book and library research. In my own case, a few hours of Web searching still falls fall short of 30 years of legwork. The huge number of errors I find on personal Webpages also undercuts any faith in Web research. Get thee to a library! I'll continue looking through my back issues as time permits, but there are over 700 issues to check. Stay tuned. C. __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Thanks for the help Chucks! Greg --- Chuck Hards <chuckhards@yahoo.com> wrote:
Now I see that the fault is with the selectivity of the S&T search engine.
A search using "eyepeice" with various modifiers failed to turn-up even one of my own articles, Feb. 00, on home-made eyepieces!
Here again is demonstrated one of the failings of Web searches; sometimes only an exact search term will get you what you want.
I'm still a firm believer in the superiority of good old fashioned book and library research. In my own case, a few hours of Web searching still falls fall short of 30 years of legwork. The huge number of errors I find on personal Webpages also undercuts any faith in Web research. Get thee to a library!
I'll continue looking through my back issues as time permits, but there are over 700 issues to check. Stay tuned.
C.
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Greg, I just fot back from Wyoming and saw youe post. You can have magnesium flouride applied by Joh Ross in Clearfield. He coated all four surfaces of my refractor and the 12"window in my 10". His phone number is:825-2130. His address is 423 Marilyn, Clearfield, UT 84015. Taking it to him is easier than trying to find the reference! Brent __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Great! I will do that. I am generally vehemently opposed to uncoated optics (oh no, a strong opinion ;) ). Greg --- Brent Watson <brentjwatson@yahoo.com> wrote:
Greg,
I just fot back from Wyoming and saw youe post. You can have magnesium flouride applied by Joh Ross in Clearfield. He coated all four surfaces of my refractor and the 12"window in my 10". His phone number is:825-2130. His address is 423 Marilyn, Clearfield, UT 84015. Taking it to him is easier than trying to find the reference!
Brent
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Hey, guys, MgFL2 will only work for ONE wavelength- thus the current rage over multi-coatings. Hopefully this one wavelength is centered in the visual spectrum- I didn't get that far before sleep overtook me. It is an interference coating, so thickness is critical. The idea is that the reflection off the glass surface itself is 1/2 wave out-of-phase with the reflection off the coating surface, thus they cancel out, no reflection at that wavelength. (For multiple wavelengths, you must use different materials & coat them to the thickness appropriate for the desired wavelength.) Now, you may ask, OK, no reflection, but how does that contribute to total throughput? After all, the relfected light is being cancelled by phase shifting; it's not being re-routed back through the glass to the focal plane. We have entered the weird, counterintuitive world of quantum mechanics and probabilities...apparently, if no light is lost to reflection, it must be going through with the rest! I know, I don't fully understand it either. But make sure that Mr. Ross knows what wavelength you want to dampen- that will determine the coating thickness. Just seeing a blue tint on your glass is indicative of- a blue tint. Brent, did you do any throughput tests, before and after? I'd like to see Mr. Ross's work. Does he have a website, or brochure perhaps? A local source is SO convenient! Chuck --- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Great! I will do that. I am generally vehemently opposed to uncoated optics (oh no, a strong opinion ;) ).
Greg
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Greg,
I just fot back from Wyoming and saw youe post. You can have magnesium flouride applied by Joh Ross in Clearfield. He coated all four surfaces of my refractor and the 12"window in my 10". His phone number is:825-2130. His address is 423 Marilyn, Clearfield, UT 84015. Taking it to him is easier than trying to find the reference!
Brent
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Chuck, No I didn't do any throughput testing. I do think the contrast increased slightly, but the secondary color also is more apparent (My estimations). John Ross does this in his basement at home. He is retired from Hiill AFB where he did this for a living. Therefore, he has no brochures, no web site, and works from word of mouth only. He will do any coating, including aluminum and gold. Some folks around have a different opinion as to quality, but Ihave had no complaints with his work. He can do up to about 16" optics. Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Hey, guys, MgFL2 will only work for ONE wavelength- thus the current rage over multi-coatings. Hopefully this one wavelength is centered in the visual spectrum- I didn't get that far before sleep overtook me.
It is an interference coating, so thickness is critical. The idea is that the reflection off the glass surface itself is 1/2 wave out-of-phase with the reflection off the coating surface, thus they cancel out, no reflection at that wavelength. (For multiple wavelengths, you must use different materials & coat them to the thickness appropriate for the desired wavelength.)
Now, you may ask, OK, no reflection, but how does that contribute to total throughput? After all, the relfected light is being cancelled by phase shifting; it's not being re-routed back through the glass to the focal plane.
We have entered the weird, counterintuitive world of quantum mechanics and probabilities...apparently, if no light is lost to reflection, it must be going through with the rest! I know, I don't fully understand it either.
But make sure that Mr. Ross knows what wavelength you want to dampen- that will determine the coating thickness. Just seeing a blue tint on your glass is indicative of- a blue tint.
Brent, did you do any throughput tests, before and after?
I'd like to see Mr. Ross's work. Does he have a website, or brochure perhaps? A local source is SO convenient!
Chuck
--- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Great! I will do that. I am generally vehemently opposed to uncoated optics (oh no, a strong opinion ;) ).
Greg
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Greg,
I just fot back from Wyoming and saw youe post. You can have magnesium flouride applied by Joh Ross in Clearfield. He coated all four surfaces of my refractor and the 12"window in my 10". His phone number is:825-2130. His address is 423 Marilyn, Clearfield, UT 84015. Taking it to him is easier than trying to find the reference!
Brent
Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
--- Brent Watson <brentjwatson@yahoo.com> wrote:
No I didn't do any throughput testing. I do think the contrast increased slightly, but the secondary color also is more apparent (My estimations).
If the coating tint is blue, then you should see a slight increase in the red end of the spectrum (yellow, orange, red) and a decrease in the blue. Very slight. Is this what you see? Did he do all four surfaces of your objective?
John Ross does this in his basement at home. He is retired from Hiill AFB where he did this for a living. Therefore, he has no brochures, no web site, and works from word of mouth only. He will do any coating, including aluminum and gold.
Sounds like he's doing vacuum deposition and not a chemical etch, yes?
Some folks around have a different opinion as to quality, but Ihave had no complaints with his work. He can do up to about 16" optics.
I would like to speak with him; if he can give a working coating, this is a boon to local bottom feeders like me. But, if it's just a blue tint with little or no througput gain- well, I don't pay money for "comfort factors". I work only a mile down the road from Skypark, Brent, how often are you at the hangar? Ever have lunch at Leger's? Maybe we can get together for lunch one day soon. BTW, some of the "do-it-yourself" coating article has come back to me- I seem to remember that it was a nitric acid dip, with some neutralizer afterwards. The acid pits the optical surface on a 1/4-wavelength scale, so you get the same effect as a deposited coating- the light reflecting off the bottom of the pits is 1/2 wave out of phase with the light reflecting off the unpitted surface. Because the pits are so small, optical performance is not negatively affected, in fact is increased due to the anti-reflection properties. You can't even detect them during testing. But nitric acid is really wicked stuff. I wouldn't recommend this for anyone who hasn't had at least AP Chemistry in high-school, or a college lab of at least the 300 level. Chuck __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Brent Watson wrote:
...He will do any coating, including aluminum and gold.
In case anyone is wondering, Brent is not kidding about gold mirrors. A few years ago Bruce Grim was having trouble with his mirror holding on to its coatings (the mirror had accidentally been impregnated by oil during fabrication). So after several failed aluminum coatings he had John strip the mirror down and apply a gold coating. Held up longer than aluminum, views through the scope looked the same and IR photometry was enhanced. And talk about pretty. Looked great (almost as good a Celestron orange <g>). BTW, eventually the gold came off too so Bruce finally fixed the problem for good by having John again strip the mirror and then apply a chrome coat and an aluminum coat over that. Patrick
BTW, Chuck, he is very knowledgable about coatings. Give him a call and talk to him. You can tell him I gave you his name. You can see my refractor and my 10" at my hangar. Come on by during one of our mirror grinding sessions. Thursday eve. from 7-10. Brent --- Chuck Hards <chuckhards@yahoo.com> wrote:
Hey, guys, MgFL2 will only work for ONE wavelength- thus the current rage over multi-coatings. Hopefully this one wavelength is centered in the visual spectrum- I didn't get that far before sleep overtook me.
It is an interference coating, so thickness is critical. The idea is that the reflection off the glass surface itself is 1/2 wave out-of-phase with the reflection off the coating surface, thus they cancel out, no reflection at that wavelength. (For multiple wavelengths, you must use different materials & coat them to the thickness appropriate for the desired wavelength.)
Now, you may ask, OK, no reflection, but how does that contribute to total throughput? After all, the relfected light is being cancelled by phase shifting; it's not being re-routed back through the glass to the focal plane.
We have entered the weird, counterintuitive world of quantum mechanics and probabilities...apparently, if no light is lost to reflection, it must be going through with the rest! I know, I don't fully understand it either.
But make sure that Mr. Ross knows what wavelength you want to dampen- that will determine the coating thickness. Just seeing a blue tint on your glass is indicative of- a blue tint.
Brent, did you do any throughput tests, before and after?
I'd like to see Mr. Ross's work. Does he have a website, or brochure perhaps? A local source is SO convenient!
Chuck
--- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Great! I will do that. I am generally vehemently opposed to uncoated optics (oh no, a strong opinion ;) ).
Greg
--- Brent Watson <brentjwatson@yahoo.com> wrote:
Greg,
I just fot back from Wyoming and saw youe post. You can have magnesium flouride applied by Joh Ross in Clearfield. He coated all four surfaces of my refractor and the 12"window in my 10". His phone number is:825-2130. His address is 423 Marilyn, Clearfield, UT 84015. Taking it to him is easier than trying to find the reference!
Brent
Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
I've looked manually through over 250 issues today, so far with no success. I also sent an email to a contact at S&T, so we'll see if it bears fruit. I'll keep looking elsewhere, too. It may be that I saw the article in a different publication. I did come across Bill's article-hey man, you look ten years younger in the magazine photo! ;) If any other "old timers" remember this article, please jump in (Brent W., Bill K., Bruce G., Siegfried J., Patrick W.?) C. __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
Might have been because I was 10 years younger :-) Bill Kelley ----- Original Message ----- From: "Chuck Hards" <chuckhards@yahoo.com> To: <utah-astronomy@mailman.xmission.com> Sent: Sunday, February 16, 2003 2:14 PM Subject: Re: [Utah-astronomy] Comet Catcher (lens coating)
I've looked manually through over 250 issues today, so far with no success. I also sent an email to a contact at S&T, so we'll see if it bears fruit.
I'll keep looking elsewhere, too. It may be that I saw the article in a different publication.
I did come across Bill's article-hey man, you look ten years younger in the magazine photo! ;)
If any other "old timers" remember this article, please jump in (Brent W., Bill K., Bruce G., Siegfried J., Patrick W.?)
C.
__________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.com
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
participants (5)
-
Bill Kelley -
Brent Watson -
Chuck Hards -
Greg Taylor -
Patrick Wiggins