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Equipment Discussions >> Reflectors

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BillShort
member


Reged: 11/06/09

Loc: Corner Brook, Newfoundland,Can...
Re: What's on this secondary? new [Re: howard929]
      #5925244 - 06/17/13 11:06 AM

Can anyone tell me just how many pinholes can be on a mirror before it is necessary for a recoat? I have a 10 inch mirror with several dozen pinholes that show from the back with a bright light. It is berol coated,about 8 to 10 years old,but rearly used. Thanks Bill

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Starman1
Vendor (EyepiecesEtc.com)
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Reged: 06/24/03

Loc: Los Angeles
Re: What's on this secondary? new [Re: howard929]
      #5925278 - 06/17/13 11:23 AM

Quote:

Hey Don,

Since you're here and I know you to be quite knowledgeable, I'll ask you a question.

I removed some milk jug washers that were behind my secondary mirror holder since they were too rutted out to be of much use. Should I PM you a photo of them or just use my telescope to view the heavens?

(sorry ALL, i just had to...)



Well, actually, you have to use two-part epoxy to put them back in the milk jugs they came out of before the milk leaks out. Make sure, though, that the grain of the plastic lines up.


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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's on this secondary? new [Re: BillShort]
      #5925335 - 06/17/13 11:54 AM

Quote:

Can anyone tell me just how many pinholes can be on a mirror before it is necessary for a recoat? I have a 10 inch mirror with several dozen pinholes that show from the back with a bright light. It is berol coated,about 8 to 10 years old,but rearly used. Thanks Bill




That's a good question. Thanks for asking as I'm interested in the answer to. But I bet the answer is "it depends on how bad you think the view is degraded by the missing reflective material." Several dozen 'pin' holes probably doesn't qualify as bad as my new secondary, freshly coated, has a lot more than several dozen across its face and I was told this is normal.

You could post a picture of it for better clarity but you may be ridiculed for asking such a question as this forum isn't intended for that sort of learning which could be construed as questioning the optical quality of something. As Howard suggests, just use your scope to look at the heavens and don't ask questions.

Rob

Edited by robininni (06/17/13 11:56 AM)


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KerryR
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Reged: 12/05/07

Loc: SW Michigan
Re: What's on this secondary? new [Re: robininni]
      #5925494 - 06/17/13 01:01 PM

I'm not sure things like "spend some time enjoying your scope and watch out for falling prey to overly obsessive testing/worrying, particularly while developing observing skills" qualify as ridiculing. I thought the participants in your recent threads have been quite supportive and respectful, mostly intended to reduce unnecessary anxiety.

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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's on this secondary? new [Re: KerryR]
      #5925612 - 06/17/13 01:57 PM

Quote:

I'm not sure things like "spend some time enjoying your scope and watch out for falling prey to overly obsessive testing/worrying, particularly while developing observing skills" qualify as ridiculing. I thought the participants in your recent threads have been quite supportive and respectful, mostly intended to reduce unnecessary anxiety.




I agree, the advice you listed in quotes doesn't sound like ridicule to me either. But I guess you accidentally skipped over Howard's smart *BLEEP* post a few replies back? Read that one and I think you'll find the ridicule I mentioned.

Many of you have great scopes and optics and some of you don't. Perhaps most of you have not found reason to investigate any optical issue and therefore don't care much for the intricacies of the subject and would rather just use the telescope. Others, like me, either have had reason to investigate the subject further or are just plain interested in the details.

I am learning as much as I can about telescope optics as they pertain to me, mainly reflectors. I am learning the answers to the questions not given in the owners manuals. Some of the information is cut and dry, based upon objective measurements and characteristics (Strehl Ratios, Transverse error, mirror vs ambient temperature, center sticker placement). I find it interesting how this objective information is looked at subjectively by some therefore watering down its usefulness. However, there certainly is some subjective material with optics, based upon perception or a 'judgement call' because there isn't a good way to measure the issue (such as when to recoat optics--how many pinholes are too many, how much light should shine through the back, how can one easily measure how much light is reflected vs absorbed?).

I suspect others are on the same quest I am to really understand the characteristics of the instruments. It doesn't take years of observing to start learning this. Asking questions, reading, measuring things and making comparisons--this will facilitate learning along side observing. One thing that will not facilitate learning is not being critical of the subject.

I am currently reading Star Testing Astronomical Telescopes, 2nd Edition. So far it is very good and very enlightening. At the end of the foreword, Richard Berry states "If your telescope has properly adjusted and excellent optics, the star test will confirm that fact--and you are free to turn your attention to observing the splendors of the heavens." Sounds to me like he thinks it is pretty important to be focused and concerned about your optics and then, after all is well, observe the heavens.

Rob


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KerryR
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Reged: 12/05/07

Loc: SW Michigan
Re: What's on this secondary? new [Re: robininni]
      #5925663 - 06/17/13 02:21 PM

I didn't accidentally or deliberately skip it, I just didn't understand what he meant. I'm still not really sure. Even if that post was intended to be malicious, that's one post out of many, and certainly doesn't indicate that the general atmosphere on CN is one of ridicule.

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GlennLeDrew
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Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: What's on this secondary? new [Re: robininni]
      #5925673 - 06/17/13 02:30 PM

If I had to pin down a number for an acceptable number of pinholes in an aluminized coating, I might go with 10 per square inch (2 per square centimeter.) It would be worth knowing just what number of pinholes within the pupil start to become problematic...

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LivingNDixie
TSP Chowhound
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Reged: 04/23/03

Loc: Trussville, AL
Re: What's on this secondary? new [Re: GlennLeDrew]
      #5925815 - 06/17/13 03:51 PM

What about residue from if the scope really dewed over, SCTs can get a weird residue if they dew over and there is enough dust or the right kind kind of dust.

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Vic Menard
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Reged: 07/21/04

Loc: Bradenton, FL
Re: What's on this secondary? new [Re: robininni]
      #5925824 - 06/17/13 03:56 PM

Quote:

...I am learning as much as I can about telescope optics...Some of the information is cut and dry, based upon objective measurements and characteristics (Strehl Ratios, Transverse error, mirror vs ambient temperature, center sticker placement).



Cut and dry?

Let's see--Strehl ratio and transverse error. How about a quote from Mike Lockwood, "Results from an interferometer are only as honest as the optician/supplier allows them to be."
Mirror vs. ambient? How close is close enough? What temperature differential is required to cause a change in correction? How significant are boundary layer effects relative to aperture? When will a smaller mirror outperform a larger mirror?
Center sticker placement? How can you tell if the mechanical center spot placement does not coincide with the optical center?

I don't think any of these are "cut and dry".

Quote:

...I find it interesting how this objective information is looked at subjectively by some therefore watering down its usefulness.



I disagree. While I think it's important to remember that the information is subjective, it is data and data can provide a useful metric. While the Strehl ratio of a mirror may vary from one manufacturer to the next, the number is useful when evaluating the individual manufacturers finished product (average, better, best). And while there's no argument with regard to managing temperature differentials, unless equilibrium is achieved, predicting image impact with single digit swings has so many variables that it's probably best to experiment and see what you get. And mechanical vs. optical centering is a lot less problematic if you keep the focal ratio above, here's a good guess, about f/5.

Quote:

...there certainly is some subjective material with optics, based upon perception or a 'judgement call' because there isn't a good way to measure the issue (such as when to recoat optics--how many pinholes are too many, how much light should shine through the back, how can one easily measure how much light is reflected vs absorbed?).



You forgot to include the effects of airborne contaminants and aging on mirror coatings. Or how about when it's safe to clean a new coating? Or how often you should clean your optics? Or when they should be replaced? And with what type of coating(s)?

Quote:

I suspect others are on the same quest I am to really understand the characteristics of the instruments. It doesn't take years of observing to start learning this. Asking questions, reading, measuring things and making comparisons--this will facilitate learning along side observing. One thing that will not facilitate learning is not being critical of the subject.



It's OK to ask questions. But when you're in the deep end, you should expect a variety of answers. You may even hear one that fits your own sensibility and personal understanding of the problem. But rest assured, it's probably not going to be the best answer for every situation or everyone's sensibility and understanding.

Quote:

I am currently reading Star Testing Astronomical Telescopes, 2nd Edition. So far it is very good and very enlightening. At the end of the foreword, Richard Berry states "If your telescope has properly adjusted and excellent optics, the star test will confirm that fact--and you are free to turn your attention to observing the splendors of the heavens."



It's on my bookshelf--I reference it often. I've enjoyed many hours of discussion with Suiter and Berry (mostly on collimation and its impact on image performance). At this point in your 24-inch Obsession exposé, I think Berry would have cautioned you to be wary of reading too much into anomalous/distorted star test results generated by a thermally unsettled 24-inch f/4 Newtonian in average (or even good) seeing. In fact, I think he would encourage you to, "...turn your attention to observing the splendors of the heavens". I'm not trying to ridicule or dismiss your concerns. But I think you'll gain valuable insight under the stars at the eyepiece.

Sorry for the long post.


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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's on this secondary? new [Re: Vic Menard]
      #5926121 - 06/17/13 06:44 PM

Okay, Vic, I want to do battle with you a bit with some of what you said .

Quote:

Quote:

...I am learning as much as I can about telescope optics...Some of the information is cut and dry, based upon objective measurements and characteristics (Strehl Ratios, Transverse error, mirror vs ambient temperature, center sticker placement).



Cut and dry?

Let's see--Strehl ratio and transverse error. How about a quote from Mike Lockwood, "Results from an interferometer are only as honest as the optician/supplier allows them to be."
Mirror vs. ambient? How close is close enough? What temperature differential is required to cause a change in correction? How significant are boundary layer effects relative to aperture? When will a smaller mirror outperform a larger mirror?
Center sticker placement? How can you tell if the mechanical center spot placement does not coincide with the optical center?

I don't think any of these are "cut and dry".




Well, the mirror values are objective. They are cut and dry, but I suppose the amount of value you should place on them depends on who did the measuring. I'm sure some opticians would take offense to you suggesting their measurements are subjective and not cut and dry--the honest ones anyway.

Mirror vs ambient? I was told with 2 degrees Fahrenheit was close enough. If the mirror is then close enough to ambient temperature, boundary layers don't form causing issues. And of equal quality, a smaller mirror never outperforms a larger mirror.


Quote:

While I think it's important to remember that the information is subjective, it is data and data can provide a useful metric. While the Strehl ratio of a mirror may vary from one manufacturer to the next, the number is useful when evaluating the individual manufacturers finished product (average, better, best).




No. Measured data by definition cannot be subjective. What you do with the data can be subjective. The Strehl of a mirror is the strehl of that mirror (given a reasonable margin or error). There is only one accurate Strehl ratio. Whether all manufacturers are equally adept at measuring and calculating it doesn't change this fact. If you passed the same mirror from optician to optician and had them test it, you would find a repeating close range and then some outliers. The outliers are wrong. I don't know what an acceptable margin of error is, but I bet any good optician could tell us. The Strehl ratio is not only useful to the individual manufacturer if he or she does accurate testing following accepted principles.


Quote:

Quote:

...there certainly is some subjective material with optics, based upon perception or a 'judgement call' because there isn't a good way to measure the issue (such as when to recoat optics--how many pinholes are too many, how much light should shine through the back, how can one easily measure how much light is reflected vs absorbed?).




You forgot to include the effects of airborne contaminants and aging on mirror coatings. Or how about when it's safe to clean a new coating? Or how often you should clean your optics? Or when they should be replaced? And with what type of coating(s)?




When it is safe to clean you new coatings should not be subjective. The coater should be able to tell us this. As, I have recently learned, when to *recoat* them is subjective depending on how much image degradation you are okay with. I would just pic your favorite optician or telescope manufacturer and go with what they say is their guideline.

Quote:

Quote:

I suspect others are on the same quest I am to really understand the characteristics of the instruments. It doesn't take years of observing to start learning this. Asking questions, reading, measuring things and making comparisons--this will facilitate learning along side observing. One thing that will not facilitate learning is not being critical of the subject.



It's OK to ask questions. But when you're in the deep end, you should expect a variety of answers. You may even hear one that fits your own sensibility and personal understanding of the problem. But rest assured, it's probably not going to be the best answer for every situation or everyone's sensibility and understanding.




This makes sense .

Quote:

Quote:

I am currently reading Star Testing Astronomical Telescopes, 2nd Edition. So far it is very good and very enlightening. At the end of the foreword, Richard Berry states "If your telescope has properly adjusted and excellent optics, the star test will confirm that fact--and you are free to turn your attention to observing the splendors of the heavens."



It's on my bookshelf--I reference it often. I've enjoyed many hours of discussion with Suiter and Berry (mostly on collimation and its impact on image performance). At this point in your 24-inch Obsession exposé, I think Berry would have cautioned you to be wary of reading too much into anomalous/distorted star test results generated by a thermally unsettled 24-inch f/4 Newtonian in average (or even good) seeing. In fact, I think he would encourage you to, "...turn your attention to observing the splendors of the heavens". I'm not trying to ridicule or dismiss your concerns. But I think you'll gain valuable insight under the stars at the eyepiece.




How do you know my scope has been thermally unsettled for all star tests? I've had it at 1-2 degrees from ambient temperature the last few nights I've used it after I changed my cool-down routine. I've had similar star test results, slightly easier to read on the inside of focus, since doing so. Your statement exemplifies something I see which I have come to dislike on CN. Experienced (in your case well respected as well) people making statements put forth as a matter of fact which actually contain assumptions (in your case, a critical one, that my mirror was not equilibrated well) but without acknowledging such premises. These statement seem to be directed at those perceived as inexperienced. Is it impossible that I have learned how to cool my big mirror down?



Rob

Edited by robininni (06/17/13 07:21 PM)


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Vic Menard
Post Laureate
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Reged: 07/21/04

Loc: Bradenton, FL
Re: What's on this secondary? new [Re: robininni]
      #5926249 - 06/17/13 08:03 PM

Quote:

...Well, the mirror values are objective.



I humbly disagree. I think you would be surprised how they are derived and how much they vary from one optician to another. I suspect this is the reason some of the best refuse to put a number on their finished product.

Quote:

Mirror vs ambient? I was told with 2 degrees Fahrenheit was close enough. If the mirror is then close enough to ambient temperature, boundary layers don't form causing issues. And of equal quality, a smaller mirror never outperforms a larger mirror.



The number of texts describing the efforts to scrub boundary layers and rapidly equilibrate and track moving temperatures in these forums alone is enough to fill a text. And that's just dealing with thermals, not correction. There's much left to be written.

Similarly, a smaller, more responsive aperture may indeed outperform a larger aperture struggling with rapid temperature changes. As I mentioned earlier, more resolving power makes larger apertures better detectors of thermal instability.

Quote:

...No. Measured data by definition cannot be subjective.



Once again, it depends on how the data is derived, how it's being measured, how many data points are being used, how the "outlier"s are handled, etc.

Quote:

...The Strehl of a mirror is the Strehl of that mirror (given a reasonable margin or error).



Even Zambuto would tell you it's fluid, and although he doesn't use an interferometer to quantify his work, Wolfgang Rohr (considered by some an expert with an interferometer) has found his work to be better than most, while showing wild disagreement with IF certified mirrors sent for evaluation. Changing the way a large, thin mirror is supported (for example, changing the altitude of the telescope), measurably changes the mirror surface--before cable slings and better edge supports, as much as a wave deformation!

Quote:

...I don't know what an acceptable margin of error is, but I bet any good optician could tell us.



I bet most "good" opticians are reticent to have their work evaluated by someone else unless they have thoroughly vetted the tester, the equipment, the method, and the reliability. Even then, I think they would prefer having a "ringside seat" to make sure their metric is either supported, or closely in line with the results of an outside testing facility. If you're looking for a "bureau of standards" reference for mirror testing reliability, you're probably not going to be able to afford it. Similarly, optical flat testing can be performed with a reference sphere or a reference flat, which even then, is dependent on the reference accuracy and the number of data points, and here we go again.

Don't get me wrong, there's a technological shift occurring with relatively inexpensive IFs (there's a thread in the ATM forum right now). All that data and number crunching can be a good thing or a bad thing...

Quote:

...When it is safe to clean you new coatings should not be subjective. The coater should be able to tell us this. As, I have recently learned, when to *recoat* them is subjective depending on how much image degradation you are okay with. I would just pic your favorite optician or telescope manufacturer and go with what they say is their guideline.



I have certain "rules of thumb" I adhere to, but, it's all subjective and dependent on many outside factors.

Quote:

...How do you know my scope has been thermally unsettled for all star tests?



I didn't say "for all star tests", but you described your first tests that way in this thread, IIRC.

Quote:

I've had it at 1-2 degrees from ambient temperature the last few nights I've used it after I changed my cool-down routine. I've had similar star test results, slightly easier to read on the inside of focus, since doing so.



Perhaps it's just atmospheric turbulence. As I mentioned in an earlier post, the scintillation you've described in your drawings is indicative of this.

Quote:

Your statement exemplifies what I have come to detest on CN. Experienced (in your case well respected as well) people making statements put forth as a matter of fact which actually contain assumptions...



When I make a comment based on an assumption, I usually note that it is, indeed an assumption. But when someone calls me out and says they "detest" my commentary, I do my best not to take it personally. I have tried to offer my insight and I've tried to be supportive of your journey. If there was a way I could be there to help, I would very much like that.

Quote:

...Is it impossible that I have learned how to cool my big mirror down?



I don't know. When my 22 is reasonably stable and seeing is as perfect as I can hope for, Sirius at 550X with full aperture is a brilliant pinpoint with steady gray ribbons defining the diffraction pattern (not a flicker). On one occasion I observed the Pup embedded in one of these ribbons, with a dark minima around it. But I'm sorry to tell you that I don't know what the temperature differential was, or just how good the seeing actually was. It was an exceptionally steady night and a serendipitous alignment. I've had similar observing moments over the past several years (sparkling stars embedded in M82 and NGC4449, surface detail on Mars during the last opposition, following Porimma through periastron, both components of the Twin Lensing Quasar, etc.). Those observations are the data points I use to define my scope's performance.


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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's on this secondary? new [Re: robininni]
      #5926292 - 06/17/13 08:32 PM

Okay, Vic, thanks for hanging in with me. I appreciate you. I also changed the 'strong' word detest to dislike, but you were too quick on the draw and quote-replied before I submitted my change.

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Vic Menard
Post Laureate
*****

Reged: 07/21/04

Loc: Bradenton, FL
Re: What's on this secondary? new [Re: robininni]
      #5926339 - 06/17/13 08:56 PM

Rob,
I do appreciate your dilemma.
Hopefully, your solution will provide a clear path from this unfortunate situation.
As Tippy D'Auria would say, "Soon it will be time, to commit astronomy!"
And then there's Plato, "He was a wise man who invented beer."

My best,

Vic Menard


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Joe G
scholastic sledgehammer


Reged: 01/10/07

Loc: Southern California
Re: What's on this secondary? new [Re: Vic Menard]
      #5926440 - 06/17/13 10:02 PM

Rob,

I have been following your various threads from the beginning. As many have pointed out, there is not always a "perfect" answer to your questions. With all dew (astro joke) respect, please consider that you are getting many answers from some of the most respected amateur/professional telescope gurus in this field. Vic, Jason, Howie, Mike, Don, etc have posted literally thousands of helpful replies for many of us asking similar questions over and over.

As you are finding out, there are a myriad of factors that affect telescopes and their performance in the real world. As many have suggested enjoy your telescope(s) and keep asking questions. But lighten up a little. The folks responding in this thread (and your many others) mean no harm and have been very helpful in ramping you up the learning curve. Imagine what your learning curve would be like if there was no Cloudy Nights?

Also, there have been relatively few vendors that have not been given a hard time on CNs. There is no plot to protect any vendor at the expense of sharing knowledge, both good and bad. Personally, I believe that the majority of the folks responding in this thread are highly objective. Learn from them.

Three nights ago, I set up my 16 inch reflector for some friends on a weekend get away. I wanted to show them Saturn. My mirror is a refigured 16 inch Lightbridge. It performed much better after the refigure (based upon a side-by-side comparison with my 12 inch Orion reflector). Much to my surprise, Saturn looked okay. No one complained about it. But stars were oblong rectangles. Of course I was frustrated and tweaked the collimation with Catseye tools, my Glatter laser, etc. Nothing changed. I had a fan blowing on the mirror for hours.

The next day I loosened the mirror clips. Voila, later that evening it made a major difference. Without CNs, I would never have known what to do or what to expect. I would not have known where or how to get my mirror refigured or recoated. I would not have known that a Glatter laser is a huge improvement over an Orion laser. I would not have purchased Vic's fine book on collimation. Nor seen Jason's many descriptions and charts and how he improved the Catseye autocollimator.

Keep asking questions. But remember these people are just trying to help.

Joe


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okieav8rAdministrator
I'd rather be flying!
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Reged: 03/01/09

Loc: Oklahoma!
Re: What's on this secondary? new [Re: Joe G]
      #5926539 - 06/17/13 11:01 PM

Quote:

Rob,

Keep asking questions. But remember these people are just trying to help.

Joe




Also remember, that at some point, you just have to let go and have fun with it. After all, it was in interest in astronomy that got you into this endeavor in the first place.


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: What's on this secondary? new [Re: robininni]
      #5926596 - 06/17/13 11:23 PM

man you don't want to know about the pinholes you see in coatings on mirrors when you do this to them.

its normal, carry on enjoy the views.

optics are never perfect, glass is never perfect. we live in an imperfect world, scrutinizing things to this level will just drive you crazy.


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frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: What's on this secondary? new [Re: frito]
      #5926630 - 06/17/13 11:40 PM

also Rob, i work in the glass industry.

specifically i run a ceramic ink jet printer that prints directly onto glass, we have the same problem with ceramic inks, a substance that is compatible with glass as its the same material and it is fused into the glass surface via heating the glass to high temperature via our tempering furnace. its extremely rare that i get a print on even small sample sized glass (12" x 12") that is completely free of pinholes.

the coating process used to put aluminum and many other materials onto the surface of glass can and will suffer the same problems if not worse ones than our process simply because those coating processes are not actually putting anything into the glass surface, they are simply layering on top of the surface via vacuum deposition

see http://en.wikipedia.org/wiki/Sputter_deposition for more info.

this process allows the coating of otherwise incompatible materials but the problem with it is durability. its durability is very low compared to a process that is fused into the glass like say our ceramic inks or pyrolytic process used in hard coat low-e's and other coating types like reflective coatings on architectural flat glass.

http://www.pilkington.com/north-america/usa/english/building+products/trade/t...

if it helps you at all to know this, minor surface defects like these effect the image extremely little, in total its probably a fraction of a percentage of light lost due to it and i would wager that one could search the world and never find a aluminum coated mirror that is free of a defect. its not worth loosing sleep over. just like in your brand new multi-thousand dollar heavy glass shower door you just bought has tons of surface defects known as pitts from the tempering process they must go through for safety requirements that the average person will never even see but if one is as picky as you are they will see them and raise holy hell over it and it has no real impact on anything ever.


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Vic Menard
Post Laureate
*****

Reged: 07/21/04

Loc: Bradenton, FL
Re: What's on this secondary? new [Re: frito]
      #5927184 - 06/18/13 10:30 AM

The advice that Rob was/is seeking was not unsolicited, and while some responses may have seemed unwarranted, in retrospect, his enthusiastic curiosity (and subsequent angst) is both genuine and "normal" considering the step up in aperture (10 to 25) and the unforeseen detours along the way.

Many of us have encouraged Rob to get in some serious observing time to get a better idea of his scope's performance. (Sometimes, not "knowing" can make a big difference, but in this case, Pandora's box has already been opened.)

Tom Clark is a good friend and an old observing buddy from Chiefland, Florida (he's since moved to New Mexico for even darker skies). I often describe Tom's observing method as "brute force" astronomy. His 42-inch f/4 GoTo Dobsonian is the largest scope I've looked through, and for the 10 years he had the scope in Chiefland, he invited an awful lot of folks to climb the movable stairwell to the eyepiece for the brilliant views of many deep sky "showcase" objects. For reference, "low" power (31mm Nagler and Paracorr = about 7mm exit pupil) on this scope is 158X (about 0.5-degree tfov). IIRC, Tom's pretty fond of his new ES20 (245X at 0.4-degree tfov--still less than 6X per inch of aperture). On their way to New Mexico, his 42-inch mirror and 7-inch m.a. secondary spent some time at Mike Lockwood's shop. The story is here.

This isn't intended to admonish Rob for expecting to receive what he thought he purchased! While Tom was pretty sure his optics weren't Mike Lockwood class, I think if he had known how bad they really were it could have spoiled those 10 years of observing fun in Chiefland.

Of course, now Tom's optics are Mike Lockwood class, and soon, the comparisons will begin. But the optics have a new home now too, so will Mike get all the credit, or will Tom attribute part of the performance to New Mexico skies? I know--we'll ask Jeannie!


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dave brock
professor emeritus


Reged: 06/06/08

Loc: Hamilton, New Zealand
Re: What's on this secondary? new [Re: Vic Menard]
      #5928617 - 06/19/13 02:15 AM

Quote:

This isn't intended to admonish Rob for expecting to receive what he thought he purchased! While Tom was pretty sure his optics weren't Mike Lockwood class, I think if he had known how bad they really were it could have spoiled those 10 years of observing fun in Chiefland.




Maybe if he had done what Rob is doing he would have had the optics refigured ~ 10 years ago and would have enjoyed his scope even more over that time?

Dave


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Re: What's on this secondary? new [Re: dave brock]
      #5928828 - 06/19/13 09:00 AM

Quote:

...Maybe if he had done what Rob is doing he would have had the optics refigured ~ 10 years ago and would have enjoyed his scope even more over that time?



I'm not so sure it was possible back then--42-inch aperture optical work had limited takers--and that's not even considering pickup and delivery!

But as I commented above, let the comparisons begin...


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