Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Reflectors

Pages: 1 | 2 | 3 | 4 | 5 | (show all)
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Why are high-quality mirrors so expensive?
      #5714805 - 03/05/13 04:20 PM

This is probably a dumb question, but I'm sure many can tell me why it is. As I understand it, many mirror makers use or will soon be using robotic equipment. Now, to an uneducated person like me, this sounds like they take a great blank, put it into a slot, switch on the power, and presto - out comes a newly-minted mirror ready for coating. I know they must inspect & test somehow.

Now, why can't they churn out dozens a day? Are materials scarce? Does the grinding take a long time? Are there many points where humans intervene to check or modify?

I can understand where the equipment may be expensive and costs need to be recouped. I can understand where QC might be critical and labor-intensive.

But what accounts for the cost difference between Chinese robotic manufacture & US robotic manufacture? Chinese mirrors may be terrific or poor. I get that. A Zambuto will never be anything but terrific. Is that strictly a QC thing? Does he have better robotics? Or does he keep tweeking as many runs as he needs to get a great mirror while the Chinese simply pull them off the assembly line after a single run?

So why am I naive and misunderstanding the mirror making process. Are we getting closer to the day when robotics will be able to consistently produce Zambuto-like mirrors routinely, consistently & in large quantity over short time spans?


Post Extras: Print Post   Remind Me!   Notify Moderator  
csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5714816 - 03/05/13 04:23 PM

Unlike the Chinese mirrors where "close is good enough", If a Zambuto mirror doesn't meet Carl's specs....it makes a good ashtray, Carl won't put it in a scope.

Post Extras: Print Post   Remind Me!   Notify Moderator  
KerryR
Carpal Tunnel
*****

Reged: 12/05/07

Loc: SW Michigan
Re: Why are high-quality mirrors so expensive? new [Re: csrlice12]
      #5714830 - 03/05/13 04:31 PM

Some, if not most, of the difference in cost also relates to the hourly wage difference between high end mirror makers and Asian workers. The issue compounds-- more time spent at a higher cost.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Deep13
Carpal Tunnel
*****

Reged: 01/25/05

Loc: NE Ohio
Re: Why are high-quality mirrors so expensive? new [Re: KerryR]
      #5714921 - 03/05/13 05:13 PM

labor and skill intensive, economy of scale (small in this case)

Post Extras: Print Post   Remind Me!   Notify Moderator  
David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5714931 - 03/05/13 05:20 PM

While mass-produced mirrors are definitely getting better, their smoothness and precise figure will rarely match that of some of the better custom mirror makers like Zambuto or Lockwood. Then, the main factor is time. Time (and a fine touch) is needed to get the mirrors to the very high level of surface accuracy and smoothness that makes these mirrors really work well for the demanding observer. With machine grinding and quick figuring, you can put out a lot of mirrors of acceptable quality in a shorter period of time, but these mass-producing mirror manufacturers just can't afford to take the extra time needed to really make darn sure that the surfaces are simply as good as they can be (time is money after all). It is that hand figuring and repeated measurement of the professional optician that gets the quality of the custom mirrors to a very high level. Is the extra quality worth the extra cost? Well, maybe yes and maybe no, but for my money, the mass produced mirror I got was not even of acceptable quality. Now that Lockwood has refigured it to premium specs, I am secure in the knowledge that the optics of my telescope are simply as good as they can ever be. Clear skies to you.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Why are high-quality mirrors so expensive? new [Re: David Knisely]
      #5715006 - 03/05/13 06:07 PM

David's right, it's time spent, AND materials.

It might be OK if polished for a certain period of time. If you double that time, the surface may be even smoother, but you've just cut your production in half. And, if I understand it right, the time spent to make a just OK surface into a superb surface cuts production to a small fraction of the quantity. Since time = money, excellence = expensive.

And there is also a difference in materials. Many inexpensive mirrors are made of plate glass or BK7 or some less-expensive material. High end mirrors are made of Borosilicate glass or fused quartz or ULE materials or zero-expansion glass types, which can literally be 10-20X as expensive (and more).

There is even a difference in roundness, wedge, quality of edge bevel, and annealing between production telescope mirrors and the premium stuff.

Is the difference worth spending? Well, that's a personal matter each of us decides. For me, the very small incremental difference in visual quality going from a premium mirror to an ultra-premium mirror was worth it, even though the difference was less than going from a production mirror to a premium mirror. I could see a difference, and as long as I could see a difference, I was not going to rest until I had the best of the best.

Because we're talking very small differences in money, here. Compare a Hyundai with a Lamborghini. That difference in price, both in dollars and percentage is WAY more than the difference between a cheap mirror and one of the best made. Sure, it depends on your economic position in life, but, the way I look at it, it's all about priorities. The very best eyepieces and the very best mirror cost small fractions of even a cheap boat. As hobbies go, this is a relatively cheap one. And that goes a long way toward explaining why so many people have cases full of eyepieces. My high-end dob, with a high-end mirror still cost less than the camera a close friend uses on his scope, and he paid almost as much for his scope and mount as my wife and I spent on new cars---combined! It's all about priorities.

David did it an economical way: get a production scope, have the mirror refigured to a premium level, and still pay a fraction of the price of a decent astrophotography rig. I'm sure he will be tinkering with the mechanicals of his scope (or already has), but the idea is good--it's the optics that we look through, not the wood in the base or the tube material or the bearings or the mirror cell. In fact, if you're good at woodworking, you could build a scope wherein the mirrors were 75% of the overall cost. Most of us aren't machinists or carpenters, though.

But, after the optics, the rest is just details.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5715080 - 03/05/13 06:45 PM

Unless you are dealing with meter class optics, good mirrors still require a good deal of work by hand. While machines do very well for excavating the curve and the polising, they fall short for the critical figuring process. It's very difficult to make a good large mirror, and opticians who do this work often have to put many hours into the figuring and testing, itself requiring a lot of skill to carry out. Yes you can get a good mirror that is mass produced, but a truly great mirror has to be at least partially handmade. The glass blanks are also very expensive, and so is the equipment required to produce optics commerically.

Taras


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Re: Why are high-quality mirrors so expensive? new [Re: Achernar]
      #5715110 - 03/05/13 06:56 PM

So, even if someone uses robotics to do the work, hand figuring is required? What does that mean? The glass comes out of the robotics, tested, found slightly off, and is polished by recalibrating the robotics or done somehow manually? I am completely uneducated here - does figuring = grinding out imperfections? So robotics get the glass close, then in comes the human and somehow manually finishes the final polishing after extensive testing?

I can certainly understand that better grade of materials being used by premium mirror makers upping the price.

Edited by Dragonwatcher (03/05/13 06:59 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
nirvanix
Carpal Tunnel


Reged: 06/07/07

Loc: Saskatoon, SK
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5715148 - 03/05/13 07:12 PM

A nominal hourly rate for such work is likely 10 or more times higher here than Asia.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5715180 - 03/05/13 07:24 PM

Quote:

So, even if someone uses robotics to do the work, hand figuring is required? What does that mean? The glass comes out of the robotics, tested, found slightly off, and is polished by recalibrating the robotics or done somehow manually? I am completely uneducated here - does figuring = grinding out imperfections? So robotics get the glass close, then in comes the human and somehow manually finishes the final polishing after extensive testing?

I can certainly understand that better grade of materials being used by premium mirror makers upping the price.




Jackie:

It is probably worth thinking about the accuracy that is required for the surface of a mirror. Generally optics are measured in terms of lambda, the wave length of light. For visual optics, typically lambda is 550nm, the wave length of green light. To get a feel for how small that really is, a human hair is about 200 times lambda.

Mirrors are measured in fractions of lambda, an average mirror might be 1/4 wave. I believe that is wave front error, a reflection doubles the surface error so that's a measure of the surface error over the entire mirror, it is perfect within something like 1/1600th the thickness of human hair. A good mirror is probably 1/10th wave, at the surface about 25nanometers.

So there you have a piece of glass maybe 10, 15, 20 inches in diametar, with a surface that is parabolic to within maybe 20 nanometers....

Such precision requires attention to each and every detail. Just the heat generated by a few quick polishes must be allowed to equilibrate before the mirror can be tested. In the book "the Perfect Machine", the story of the Hale 200 inch at Palomar, the final figuring was done in a basement that was temperature controls. Each week the mirror would be tested, polished for a very short while and then allowed to wait a week for the next test.

Amateur astronomers make their own mirrors. You could make one too.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Re: Why are high-quality mirrors so expensive? new [Re: Jon Isaacs]
      #5715192 - 03/05/13 07:33 PM

Jon,

Thanks. I guess I never thought about the substrate needing to "rest" between polishes to come to equilibrium. I suppose temperature, air particulates, material interactions, gases, etc all come into play. So robotics don't control all the variables, requiring human intervention...

I know some amateurs grind their own mirrors. I know a couple... I can understand the painstaking, time-consuming nature of that. It's a labor of love and pride often. But I wasn't understanding why automatic robotics needed tinkering with if well implemented. I am beginning to see now...

Edited by Dragonwatcher (03/05/13 07:36 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5715237 - 03/05/13 07:55 PM

Superior craftsmanship, quality control, good process, professional reputation--just to name a few.

Post Extras: Print Post   Remind Me!   Notify Moderator  
GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5715249 - 03/05/13 08:00 PM

Don,
Good answer. If you buy the right telescope, it will last a lifetime. If on a limited budget, the Chinese made mirrors for the most part give good value for the money. However, I am at the time of my life when I will only buy premium mirrors for my telescopes. My goal is to spend all my money before I die. My kids believe in the survival of the fittest. So, why die and leave them rich?


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Why are high-quality mirrors so expensive? new [Re: GeneT]
      #5715254 - 03/05/13 08:03 PM

Getting that last 10% of improvement can take 90% of the time.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jason D
Postmaster
*****

Reged: 10/21/06

Loc: California
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5715274 - 03/05/13 08:18 PM

There is a more basic answer and that is supply and demand. As long as the price convinces the master optician to stay in business and as long as the same price will attract enough buyers then that sets the “fair” price regardless of its amount.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Jason D]
      #5715666 - 03/06/13 12:14 AM

I've quickly scanned the thread and have this:

There are a number of misconceptions:

#1 Mirror makers are using robotic equipment. Not so, not so, not so.... show me one mirror maker that caters to the amateur market that is using "robotic" equipment to figure mirrors. I only know of ONE person that claims so but has shown no evidence of doing so.


#2. Don Pensack made a statement of "time and materials". Nope... it's just time. My materials cost for figuring mirrors is insignificant. PITIFULLY SMALL. Its the time and therefore the overhead of my shop that drives the cost.

What drives the cost of a "good" mirror up is the added time to take it from what some consider acceptable, to what "high quality" mirror makers consider acceptable. To put this in understandable terms:

What you are paying for is the additional labor and overhead. Figuring a mirror from 1/4 wave to 1/8th wave or better is purely art that only a handful of people on earth have learned how to do on a commercial scale.

And... to top it off we all do it for a pitifully low wage when you consider our labor input and overhead. I'm sure many other mirror makers will chime in and back me up on the fact that we don't do it for the money alone.

Edited by ausastronomer (03/06/13 06:37 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
jpcannavo
scholastic sledgehammer
*****

Reged: 02/21/05

Loc: Ex NYCer, Now in Denver CO!
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5715866 - 03/06/13 06:32 AM

Quote:

This is probably a dumb question, but I'm sure many can tell me why it is. As I understand it, many mirror makers use or will soon be using robotic equipment. Now, to an uneducated person like me, this sounds like they take a great blank, put it into a slot, switch on the power, and presto - out comes a newly-minted mirror ready for coating.




I think there is a misunderstanding here. Even for mass produced mirros, the above description is a qualitative oversimplification of a process that still requires a significant human involvement. I don't think - and anyone please correct me if wrong - we are anywhere close to such an entirely robotic process that yields a polished, figured surface for typical mass produced mirror. As such, the already required hands-on-human element becomes far more time-intensive when trying to obtain premium results. And so, price goes up accordingly.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5717310 - 03/06/13 09:23 PM

Quote:


There are a number of misconceptions:

#1 Mirror makers are using robotic equipment. Not so, not so, not so.... show me one mirror maker that caters to the amateur market that is using "robotic" equipment to figure mirrors. I only know of ONE person that claims so but has shown no evidence of doing so.




Perhaps you are correct. I was under the impression that one NW mirror maker does, it's done in China, and when I go to the site for Veritas Optics I see the message "Veritas Optics is currently implementing robotic figuring/testing systems to produce the highest quality medium to large aperture primary mirrors. Availability expected mid 2013."

So if I have jumped the gun in my assumption and robotics are not currently being used by many/any mirror makers, then I apologize for making an unfounded statement.

Also, I wonder if we could be dealing with a semantics issue? I may not have a clear understanding of robotics from an engineering/manufacturing point of view. Does largely automated fall short of the definition of robotics?


Post Extras: Print Post   Remind Me!   Notify Moderator  
mark cowan
Vendor (Veritas Optics)
*****

Reged: 06/03/05

Loc: salem, OR
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5717390 - 03/06/13 10:12 PM

I've had to change that a few times already, as the difficulty involved keeps pushing my timeline back.

Best,
Mark


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5717448 - 03/06/13 10:40 PM

Quote:

I've quickly scanned the thread and have this:

There are a number of misconceptions:

#1 Mirror makers are using robotic equipment. Not so, not so, not so.... show me one mirror maker that caters to the amateur market that is using "robotic" equipment to figure mirrors. I only know of ONE person that claims so but has shown no evidence of doing so.


#2. Don Pensack made a statement of "time and materials". Nope... it's just time. My materials cost for figuring mirrors is insignificant. PITIFULLY SMALL. Its the time and therefore the overhead of my shop that drives the cost.





so far as I know, commercial scopes from China do not use fused quartz, Zerodur, ULE materials, and I'm not even sure they use borosilicate glass.
So there would, indeed, be a significant difference in materials cost.
Admittedly, though, materials are not a significant part of the difference in price between premium mirrors and those in commercial scopes from China.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff Morgan
Postmaster
*****

Reged: 09/28/03

Loc: Prescott, AZ
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5717470 - 03/06/13 10:49 PM

Quote:

And there is also a difference in materials. Many inexpensive mirrors are made of plate glass or BK7 or some less-expensive material. High end mirrors are made of Borosilicate glass or fused quartz or ULE materials or zero-expansion glass types, which can literally be 10-20X as expensive (and more).




Even in things as innocuous as pitch and cerium oxide.

Or in letting a mirror set in the stand for three hours before testing, vs. 30 seconds.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5717482 - 03/06/13 10:54 PM

The final adjustments to the mirror's surface have to be done by hand, IF you want a mirror to be as smooth and well corrected as possible. Machines do very well for hogging out the curve, and the initial polishing. The figuring is best done by hand because when a person does it the figuring strokes are somewhat random, which keeps roughness and errors to a minimum. Figuring a large and or fast mirror is no small task, let alone the testing to see what needs to be done next or if the mirror is finished. That can take quite some time. Also, premium mirror makers can make your mirror from any sort of low-expansion glass or glasslike material you want. That alone is quite expensive, but worth it because they are easier for the optician to work on, and you won't have to deal with the mirror's figure shifting when the mirror is cooling down to ambient temperature.

Taras


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Why are high-quality mirrors so expensive? new [Re: Achernar]
      #5717541 - 03/06/13 11:53 PM

When I make 12.5" f/2 primaries of elliptical figure, getting that last 10% of finesse takes at least 80% of the time devoted to aspherizing. And that's in spite of the substrate being fused silica, which allows virtually instantaneous testing due to its low coefficient of thermal expansion. Initial removal of glass can proceed quickly, with robust action of the tool. But as the final figure is approached, the pace slows down considerably so as to bring about a smooth surface of good correction.

A graph of time spent vs volume of glass removed over time would show a curve which very rapidly deflects to near horizontal for most of the process, due to the relatively minuscule amounts of glass polished away during the last 80+ per cent of work on aspherizing.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5717818 - 03/07/13 07:24 AM

Quote:

Perhaps you are correct. I was under the impression that one NW mirror maker does, it's done in China, and when I go to the site for Veritas Optics I see the message "Veritas Optics is currently implementing robotic figuring/testing systems to produce the highest quality medium to large aperture primary mirrors. Availability expected mid 2013."




"Highest quality" is probably subjective.. Reading that interferometer and deciding where to make the corrections would seem difficult to automate. If you want Roland Christen or Peter Ceravolo quality optics, someone like Roland or Peter or ... better be at the helm.

Jon


Post Extras: Print Post   Remind Me!   Notify Moderator  
azure1961p
Postmaster
*****

Reged: 01/17/09

Loc: USA
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5717854 - 03/07/13 07:51 AM

Time. It's very time intensive.

Pete


Post Extras: Print Post   Remind Me!   Notify Moderator  
turtle86
Pooh-Bah Everywhere Else
*****

Reged: 10/09/06

Re: Why are high-quality mirrors so expensive? new [Re: azure1961p]
      #5718066 - 03/07/13 10:31 AM

Quote:

Time. It's very time intensive.

Pete




Yes. Quality takes time and time is money.


Post Extras: Print Post   Remind Me!   Notify Moderator  
kfrederick
Carpal Tunnel


Reged: 02/01/08

Re: Why are high-quality mirrors so expensive? new [Re: turtle86]
      #5718096 - 03/07/13 10:40 AM

The nice thing a great mirror lasts more than a lifetime . We are blessed that there are such good mirrors to be had .

Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5718236 - 03/07/13 11:42 AM

Quote:

Quote:

I've quickly scanned the thread and have this:

There are a number of misconceptions:

#1 Mirror makers are using robotic equipment. Not so, not so, not so.... show me one mirror maker that caters to the amateur market that is using "robotic" equipment to figure mirrors. I only know of ONE person that claims so but has shown no evidence of doing so.


#2. Don Pensack made a statement of "time and materials". Nope... it's just time. My materials cost for figuring mirrors is insignificant. PITIFULLY SMALL. Its the time and therefore the overhead of my shop that drives the cost.





so far as I know, commercial scopes from China do not use fused quartz, Zerodur, ULE materials, and I'm not even sure they use borosilicate glass.
So there would, indeed, be a significant difference in materials cost.
Admittedly, though, materials are not a significant part of the difference in price between premium mirrors and those in commercial scopes from China.




Correct if we are talking about super premium mirrors, however I was thinking in terms of amateur astronomy. You just don't see any zerodur or ule mirrors in dobs and such. There are a few Asian manufacturers that do use borosilicate but most are BK7. One thing that befuddles me on the use of the BK7 is that it is torturous to anneal properly. The energy costs of annealing large chunks of bk7 is about 10 times that of borosilicate. If they find this more cost effective then Asian energy prices must be almost free.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5718285 - 03/07/13 11:58 AM

I received a P.M. from a moderator that my comments above had been edited because they violated the TOS. I had commented on the optical quality of mirrors coming out of Asia. Since I am considered a competing manufacturer I am not permitted to do so even though I rarely make new mirrors. My primary business has evolved into re-figuring these very mirrors.

So my thought is that I'm one of the very few people on earth who has handled, tested, and re-figured many hundreds of these optics. The count is in the thousand plus range now.

It's quite likely that I have the best understanding of the optical quality of the various manufacturers parabolic mirrors yet I am not allowed to bring any discussion about it into the public light. Doesn't seem right.

I'll risk saying that after ten years of testing mirrors of all makes, manufacturers and vintages the "public" would be shocked at the results.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5718319 - 03/07/13 12:18 PM

Cary,
Don't forget that your sample is "pre-selected" to exclude the better mirrors. People aren't going to send you a mirror for refiguring unless there is an issue with the mirror, i.e. the owners are not getting the results out of the mirror they think they should.
You aren't going to be sent the 16" LightBridge mirror I star tested as having one of the most perfect figures I'd ever seen on a mirror. That, of course, wasn't the average mirror, but does show the issue.

I grant you, though, that the brand names of the mirrors you are sent in significant quantities would be enlightening.


Post Extras: Print Post   Remind Me!   Notify Moderator  
KerryR
Carpal Tunnel
*****

Reged: 12/05/07

Loc: SW Michigan
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5718333 - 03/07/13 12:25 PM

On the other hand, when you send a mirror to OWL for re-coating, testing is free, isn't it? I suspect most folks sending their Asian mirrors in for re-coating would have this done. So, it'd seem likely Cary would see the figure of nearly everything coming in, re-figuring or not.

No?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: KerryR]
      #5718443 - 03/07/13 01:31 PM

Don, you may be correct. I do get the feeling that there is some pre-selction going on but as Kerry points out I get a lot of mirrors in for coating that get the free optical test too. Among those mirrors are some premium made mirrors (big names I cannot mention) that test out differently than expected.

I can also say that there is a brand/make selection process going on. I get mostly all of one asian made brand (we'll call it "Brand X") coming in for testing and refiguring and the other of the two major brands very rarely is sent in for an test / refigure. Of those "other" brand mirrors that come in for testing, only a handful (about 8 all time) warranted refiguring. When most people guess about which brand is which they almost always guess wrong. I guess this is the power of marketing? Who knows. I can say that the difference is so large that I personally would never purchase a scope with "Brand X" mirrors in them.

It does seem a shame that I am barred from sharing my ten years of experience with testing these mirrors and the public goes uneducated.

Edited by Jarad (03/08/13 08:23 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
CosmoSat
Pooh-Bah


Reged: 07/24/09

Loc: India
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5718494 - 03/07/13 01:55 PM

That "X" word might be misleading here too, it might well have been "Y"...

Clear Skies!

Edited by Jarad (03/08/13 08:27 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
FirstSight
Duke of Deneb
*****

Reged: 12/26/05

Loc: Raleigh, NC
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5718504 - 03/07/13 01:57 PM

Quote:

I get mostly all of one asian made brand (we'll call it "Brand X") coming in for testing and refiguring and the other of the two major brands very rarely is sent in for an test / refigure. Of those "other" brand mirrors that come in for testing, only a handful (about 8 all time) warranted refiguring.




Another way to look at it is that the viable continuation of your refiguring business is dependent on Brand X's lax approach to quality control of their mirrors, as well as their continuing commercial success despite that incorporating that factor into their business model. This observation is not at all intended as a negative comment about you; after all, you are being as bluntly frank and forthcoming about the true state of things as the CN TOS permits in this forum, and amounts to nothing more than a particular application of the obvious fact that if all mirrors were well-figured there would be none left to be re-figured.

Edited by Jarad (03/08/13 08:26 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: Why are high-quality mirrors so expensive? new [Re: CosmoSat]
      #5718514 - 03/07/13 02:04 PM

Quote:

That "X" word might be misleading here too, it might well have been "Y"...

Clear Skies!




I have a very good brand "%^&&&&^%##@@" mirror but the Baytronix scope/mirror I had was horrible.

Jon

Edited by Jarad (03/08/13 08:27 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: FirstSight]
      #5718526 - 03/07/13 02:13 PM

Quote:

Another way to look at it is that the viable continuation of your refiguring business is dependent on Brand X's lax approach to quality control of their mirrors, as well as their continuing commercial success despite that incorporating that factor into their business model. This observation is not at all intended as a negative comment about you; after all, you are being as bluntly frank and forthcoming about the true state of things as the CN TOS permits in this forum, and amounts to nothing more than a particular application of the obvious fact that if all mirrors were well-figured there would be none left to be re-figured.




They've already made and sold more mirrors than I could ever refigure in my remaining lifetime.

Edited by Jarad (03/08/13 08:28 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
mark cowan
Vendor (Veritas Optics)
*****

Reged: 06/03/05

Loc: salem, OR
Re: Why are high-quality mirrors so expensive? new [Re: Jon Isaacs]
      #5718608 - 03/07/13 02:56 PM

Quote:

Reading that interferometer and deciding where to make the corrections would seem difficult to automate.




Well, that would be exactly the wrong way to automate the process. The correct way uses deterministic figuring that converges on the desired curve, not error correction after the fact.

The OP asked about robotic mirror production and why that hasn't resulted in lower cost high quality mirrors. It really won't result in that as far as I can see, given the expenses involved. But it will increase my production capacity many fold, while allowing the same time and attention to ultimate surface quality.

It's not as simple as putting a blank in the slot and pulling out a finished mirror, though of course I don't really believe the OP ever thought that.

It still involves a large number of steps in a complicated process. But by automating the time consuming testing and figuring steps - linked in one feedback and prediction loop - the process converges under robotic control on the desired figure. Which is all anybody really wants to see anyway.

Best,
Mark


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: Why are high-quality mirrors so expensive? new [Re: mark cowan]
      #5718672 - 03/07/13 03:26 PM

On the topic of vendors:

The rule about vendors commenting on other vendors products is there for several reasons:
1 - To protect both CN and the person posting the comments from potential lawsuits.
2 - To prevent the person being commented on from being unfairly denigrated without the opportunity respond.
3 - To preserve CN as a place where anyone (including vendors) can participate in civil discussions.

A vendor cannot claim to be unbiased about their competitor's products. There is a financial incentive to convince potential customers that a competing product is inferior. This rule goes both ways - they are also protected from being commented on by other vendors.

So let's move away from comments about a specific company's mirrors, and back to the original topic about why it costs money to achieve high quality. A vendor's experience and insights into the process are welcome, and allowed by the TOS.

Thanks,

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarrod
Pooh-Bah
*****

Reged: 01/20/13

Loc: SE USA
Re: Why are high-quality mirrors so expensive? new [Re: Jarad]
      #5718702 - 03/07/13 03:39 PM

-----
Good
Cheap
Fast

Pick two.
------

Remember this relationship. It applies to almost every product or service. Including, I expect, to telescope mirrors where "fast" could mean two things (production speed or f-ratio), both of which still make the relationship true.

Edited by Jarrod (03/07/13 03:42 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5718713 - 03/07/13 03:50 PM

Quote:

This is probably a dumb question, but I'm sure many can tell me why it is. As I understand it, many mirror makers use or will soon be using robotic equipment...




The term "robotic equipment" covers a lot of territory.

Traditional CNC machinery is often called "robotic" - it makes precise motions following a precise set of instructions for movement. Such a system provides no feedback at all to the control system, and does not have any adaptive behavior of its own.

You can't make large precision optics ONLY using a system like because it could never be precise enough to cut a final surface. Precision optics requires feedback from an iterative measuring process that guides the figuring to make the final surface.

SSG/Tinsley that makes big mirrors, and mirrors out of exotic materials, for NASA and the military uses a precision CNC system for this:
http://www.asphere.com/CA_CCOS.html

What they do is make precise measurements of the deviations from the desired figure (where and how much) then uses the CNC system to grind each mapped area down by the calculated amount, and repeats the process until the figure is final.

All this high precision stuff costs a lot of money.

More recently "robotic" systems have added adaptive behavior of their own - using optical or mechanical sensors to guide what they are doing, some even doing automated task learning. This requires a lot more computer processing power and more sophisticated software which is why it is only emerging now. This type of robotic equipment is now taking over manual tasks that resisted the former precise control paradigm.

Traditional mirror making used mechanical equipment to generate (rough out) the surface to its overall form, and then used hand guided techniques to figure it. Since humans can't do anything precisely or consistently a very different strategy of using randomized movements which inevitably combine (if truly random) to produce a very smooth unbiased surface.

The measuring process that guides this does not need to be as high-tech as the system used by SSG/Tinsley since qualitative measurements are about as useful as precise quantitative ones.

A robotic system in the recent style could do this also. Computer control would allow highly randomized figuring movements, much better than what a human can do.

One can imagine a commercial production system using such a machine and the same type of semi-qualitative measurements. With sufficient sophistication of the software, the figuring machine would use the test images directly to guide its operation.

In a mass production environment mirror cooling between measuring figuring runs would not be a problem since a number of mirrors would be in process at once, and the machine would rotate which one it was working on.

It has been pointed out here frequently that the thing that makes a premium mirror "premium" is really the consistency of the manufacturer. And this requires excellent quality control of the final product no matter how the mirror is finished.

Mass market mirror makers are under pressure to get the mirror out the door with a limited fixed amount of work invested in it to keep costs low. An adaptive system that can converge efficiently on a high quality figure could change this calculation. It would discharge a mirror from figuring once it hit the necessary quality level (and only then) and only the average amount of work per mirror would need to be considered for the cost.

I have no knowledge of such a system being developed or installed anywhere, but would be surprised if one does not eventually appear.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: careysub]
      #5719072 - 03/07/13 06:59 PM

There are two robotic start to finish figuring machines commercially available. QED is one of them and I cannot extract the other brand out of my head - they are UK based. Two slightly different technologies but they both produce near perfect aspheres.

Both of these technologies are really really really amazing. Both technologies work from interoferograms and polish the optic from it's starting state to surface figures of 1/40th wave in one pass.

Amazing comes at a price though. Entry level for both companies is around $400K for a machine that can figure up to 200mm dimaeter. Machines up to 4 meter capacity are available at a cost of many millions. There is also the support equipment, materials etc etc.. and the requirements of the optical "blanks" get quite stringent for the QED technology. QED requires the blanks to have less than 50 microns of wedge (if I recall correctly).

It CAN be done, but its out of the price range of amateur astronomy. Also consider the fact that if someone like myself invested in such machinery why would I sell optics in the several hundred dollar price point when I could produce and document similar optics, but of a much higher surface quality, and then sell them to the government in the many thousands price point.


Post Extras: Print Post   Remind Me!   Notify Moderator  
johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5719237 - 03/07/13 08:06 PM

Darn. "Robotics" - in my mind I was picturing actual robots making mirrors.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Re: Why are high-quality mirrors so expensive? new [Re: johnnyha]
      #5719639 - 03/07/13 11:30 PM

Quote:

Darn. "Robotics" - in my mind I was picturing actual robots making mirrors.




So we can one day expect our mirrors to come from R2D2 Optics, C-3PO Optics, Robby Optics, Astro-Boy Optics and Cyborg Optics? Maybe I should look into buying some domain names to later sell at huge profit!


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5719729 - 03/08/13 12:39 AM

Quote:

There are two robotic start to finish figuring machines commercially available. QED is one of them ... Two slightly different technologies but they both produce near perfect aspheres.

Both of these technologies are really really really amazing. Both technologies work from interoferograms and polish the optic from it's starting state to surface figures of 1/40th wave in one pass.

Amazing comes at a price though. Entry level for both companies is around $400K for a machine that can figure up to 200mm dimaeter. ... There is also the support equipment, materials etc etc.. and the requirements of the optical "blanks" get quite stringent for the QED technology. QED requires the blanks to have less than 50 microns of wedge (if I recall correctly).

It CAN be done, but its out of the price range of amateur astronomy. ...




Mark Cowan said (maybe giving me too much credit):
"It's not as simple as putting a blank in the slot and pulling out a finished mirror, though of course I don't really believe the OP ever thought that. "

So, if I had about 1/2 million to invest, I could produce hundreds of mirrors a year at Zambuto quality? And it would be as simple as putting them in a slot and pulling out a finished product?

Disclaimer: I don't have that much cash lying around...

Edited by Dragonwatcher (03/08/13 12:40 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
sopticals
professor emeritus


Reged: 03/28/10

Loc: New Zealand
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5719775 - 03/08/13 01:47 AM

Quote:



I can also say that there is a brand/make selection process going on. I get mostly all of one asian made brand (we'll call it "Brand X") coming in for testing and refiguring and the other of the two major brands very rarely is sent in for an test / refigure. Of those "other" brand mirrors that come in for testing, only a handful (about 8 all time) warranted refiguring. When most people guess about which brand is which they almost always guess wrong. I guess this is the power of marketing? Who knows. I can say that the difference is so large that I personally would never purchase a scope with "Brand X" mirrors in them.





This is "tricky ground", but large volume mirror makers need to be accountable for the quality of their product. Amateur astronomers should not be seen as "cash cows". If the quality of brand "A" mirrors is consistently inferior to that of brand "B", then surely the astro scope buyer has a right to know?

Edited by Jarad (03/08/13 08:29 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5719783 - 03/08/13 01:56 AM

Quote:

...

Both of these technologies are really really really amazing. Both technologies work from interoferograms and polish the optic from it's starting state to surface figures of 1/40th wave in one pass.

Amazing comes at a price though. Entry level for both companies is around $400K for a machine that can figure up to 200mm dimaeter. Machines up to 4 meter capacity are available at a cost of many millions. There is also the support equipment, materials etc etc.. and the requirements of the optical "blanks" get quite stringent for the QED technology. QED requires the blanks to have less than 50 microns of wedge (if I recall correctly)....




I Googled the website and you are not kidding. Magnetorheological polishing - a combination of magnetic, hydrodynamic and mechanical effects. This is real "rocket science" and it produces fantastic precision.
http://www.qedmrf.com/polishing/mrf-technology/how-it-works

What I had in mind was something a bit less advanced, though this does fit the bill, just in really expensive form - the Bugatti Veyron version.

It is also definitely a classic CNC type system, taken to the nth degree.

Most (all?) technical innovations in amateur astronomy seem to be imports of techniques developed for other purposes. Adaptive robotic systems are rapidly spreading and by their nature are at least somewhat general in function. As they proliferate and the price points drop it seems inevitable that someone will take one that and modify it to make amateur telescope mirrors through more conventional tooling.

Edited by careysub (03/08/13 02:11 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5720118 - 03/08/13 09:31 AM

Quote:

Quote:

Darn. "Robotics" - in my mind I was picturing actual robots making mirrors.




So we can one day expect our mirrors to come from R2D2 Optics, C-3PO Optics, Robby Optics, Astro-Boy Optics and Cyborg Optics? Maybe I should look into buying some domain names to later sell at huge profit!




A Borg Scope. You are the scope, a mechanical eyepiece will be permanently installed in your eye (your choice, or both). You, and the photons will be assimillated....Resistance is Futile....


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: Why are high-quality mirrors so expensive? new [Re: csrlice12]
      #5720299 - 03/08/13 11:08 AM

Quote:

A Borg Scope. You are the scope, a mechanical eyepiece will be permanently installed in your eye (your choice, or both). You, and the photons will be assimillated....Resistance is Futile....




Yes, I have one. It's very nice...

http://www.sciencecenter.net/hutech/borg/solution/systems/swii.htm

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
csrlice12
Postmaster
*****

Reged: 05/22/12

Loc: Denver, CO
Re: Why are high-quality mirrors so expensive? new [Re: Jarad]
      #5720365 - 03/08/13 11:49 AM

No wonder people volunteer to be assimmillated.....

Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Costello
Carpal Tunnel
*****

Reged: 03/08/05

Loc: Matthews, NC, USA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5720528 - 03/08/13 01:20 PM

One thing I've noticed is that some "premium" Dob makers sell ther Dobs at prices in the ball park with similar size SCTs from "large" makers....

Post Extras: Print Post   Remind Me!   Notify Moderator  
BluewaterObserva
Postmaster
***

Reged: 05/18/04

Re: Why are high-quality mirrors so expensive? new [Re: csrlice12]
      #5720532 - 03/08/13 01:22 PM

I suggest the OP try to produce a good mirror.

Evevn just try to produce one to the point of decent ronchi lines.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: careysub]
      #5720556 - 03/08/13 01:34 PM

Quote:

Quote:

...

Both of these technologies are really really really amazing. Both technologies work from interoferograms and polish the optic from it's starting state to surface figures of 1/40th wave in one pass.

Amazing comes at a price though. Entry level for both companies is around $400K for a machine that can figure up to 200mm dimaeter. Machines up to 4 meter capacity are available at a cost of many millions. There is also the support equipment, materials etc etc.. and the requirements of the optical "blanks" get quite stringent for the QED technology. QED requires the blanks to have less than 50 microns of wedge (if I recall correctly)....




I Googled the website and you are not kidding. Magnetorheological polishing - a combination of magnetic, hydrodynamic and mechanical effects. This is real "rocket science" and it produces fantastic precision.
http://www.qedmrf.com/polishing/mrf-technology/how-it-works

What I had in mind was something a bit less advanced, though this does fit the bill, just in really expensive form - the Bugatti Veyron version.

It is also definitely a classic CNC type system, taken to the nth degree.

Most (all?) technical innovations in amateur astronomy seem to be imports of techniques developed for other purposes. Adaptive robotic systems are rapidly spreading and by their nature are at least somewhat general in function. As they proliferate and the price points drop it seems inevitable that someone will take one that and modify it to make amateur telescope mirrors through more conventional tooling.




Just fetched the other company from the memory banks: Zeeko

http://www.zeeko.co.uk/site/tiki-index.php?page=HomePagePublic

Again...awesome performance with the price tag to match.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Howie Glatter
Vendor


Reged: 07/04/06

Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5720563 - 03/08/13 01:36 PM

". . why would I sell optics in the several hundred dollar price point when I could produce and document similar optics . . and then sell them to the government in the many thousands price point."

Because you might have qualms about some of the things it is being used for ?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5720650 - 03/08/13 02:21 PM

Who would pony up the immense sum of money such a machine cost, and who would they be making optics for with it?

Taras


Post Extras: Print Post   Remind Me!   Notify Moderator  
Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Why are high-quality mirrors so expensive? new [Re: Mark Costello]
      #5720663 - 03/08/13 02:28 PM

Even so, a premium 15 or 16-inch Dob while expensive is a lot less expensive than a 16-inch SCT complete with mounting and pier or tripod. But yes, there are premium Dobs that are second to none in all respects, that is why they command the prices they do.

Taras


Post Extras: Print Post   Remind Me!   Notify Moderator  
Dragonwatcher
Carpal Tunnel
*****

Reged: 01/21/08

Loc: Coupeville, WA
Re: Why are high-quality mirrors so expensive? new [Re: BluewaterObserva]
      #5720700 - 03/08/13 02:56 PM

Quote:

I suggest the OP try to produce a good mirror.

Evevn just try to produce one to the point of decent ronchi lines.




Where did that come from? I was merely asking a question, not criticizing anyone or suggesting it was such an easy project even a klutz like I could do it. Making a mirror is way beyond my interests or skills. I was simply looking for an explanation of why there exists such a wide range of pricing for mirrors and how automation might fit into the picture.

I have been given many good answers so I understand some of the issues better. I don't think I need to make my own mirror to understand what people are saying.

[And you can see by my equipment list I have been happily "Borged" in the refractor domain.]


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Howie Glatter]
      #5720866 - 03/08/13 05:17 PM

Quote:

". . why would I sell optics in the several hundred dollar price point when I could produce and document similar optics . . and then sell them to the government in the many thousands price point."

Because you might have qualms about some of the things it is being used for ?




Among other things I made prototype optics for a Naval defense targeting system that identifies, tracks, and provides fire control for up to 8 moving surface targets. It's used to protect ships from incoming suicide bombers so bombings like the USS Cole don't happen again. Yes, death is involved in with things that I have made but I guess I don't have qualms about helping to kill those who would kill "us".


Post Extras: Print Post   Remind Me!   Notify Moderator  
Starhawk
Space Ranger
*****

Reged: 09/16/08

Loc: Tucson, Arizona
Re: Why are high-quality mirrors so expensive? new [Re: Howie Glatter]
      #5720869 - 03/08/13 05:18 PM

So, think about this:

Mirror Machine (Dream version): $400K
Mirror Blanks (base Quality, 200mm size): $35
Consumables/ mirror: $20
Labor/mirror: $60

I'm going to neglect coating costs since there isn't anything about the robotic grinder to make that part easier.

Mirrors needed to be sold to pay for mirror machine at-cost (assuming mirrors are sold for 40% more than above cost, $161): 8,696.

So, even if this dream machine exists, to make mirrors for dirt cheap delivered prices is going to require trainloads of them to be sold. just to break even, during which time you will be deep in the hole.

If you want a return on the investment for the machine, like 40% to have made the whole endeavor worthwhile, then we're talking about selling 12,173 of these miracle mirrors to get that point. And in this hobby, that's a lot of telescopes. In reality, you'd be unable to meet this price for the cost and stay fiscally whole.

If you talk $750 mirror, making a reasonable rate of return on the machine still requires selling 882 of them to do it. At that point, your business would have invested a total of $501,430 to earn $702,002, and the $201K you could keep would be eaten up by other costs and taxes. So, it isn't obvious there is a fortune waiting to be made this way.

If this were lens sets for iPhones, then selling stuff by the millions is possible, and one isn't a slave to trying to amortize equipment costs just to break even..

-Rich


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5720872 - 03/08/13 05:20 PM

Quote:

Quote:

I suggest the OP try to produce a good mirror.

Evevn just try to produce one to the point of decent ronchi lines.




Where did that come from? I was merely asking a question, not criticizing anyone or suggesting it was such an easy project even a klutz like I could do it. Making a mirror is way beyond my interests or skills. I was simply looking for an explanation of why there exists such a wide range of pricing for mirrors and how automation might fit into the picture.

I have been given many good answers so I understand some of the issues better. I don't think I need to make my own mirror to understand what people are saying.

[And you can see by my equipment list I have been happily "Borged" in the refractor domain.]




In a nutshell : Making high quality mirrors ain't easy and it takes a long time and time equals money.

How's that


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Costello
Carpal Tunnel
*****

Reged: 03/08/05

Loc: Matthews, NC, USA
Re: Why are high-quality mirrors so expensive? new [Re: Achernar]
      #5720880 - 03/08/13 05:29 PM

Quote:

Even so, a premium 15 or 16-inch Dob while expensive is a lot less expensive than a 16-inch SCT complete with mounting and pier or tripod. But yes, there are premium Dobs that are second to none in all respects, that is why they command the prices they do.

Taras





Hello, Taras. I was a little circumspect in my last post on this thread. To put it more bluntly and cite an example, a "mass produced" rig involving a 8"- 9.25" SCT goes for roughly the same amount of money as an 8"-11" Teeter Dob with a "premium" mirror....


Post Extras: Print Post   Remind Me!   Notify Moderator  
BillFerris
Post Laureate
*****

Reged: 07/17/04

Loc: Flagstaff, Arizona, USA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5720940 - 03/08/13 06:04 PM

Quote:

It does seem a shame that I am barred from sharing my ten years of experience with testing these mirrors and the public goes uneducated.




Write and submit an article to the astro mags. If it's not accepted, publish it on your web site.

Bill in Flag


Post Extras: Print Post   Remind Me!   Notify Moderator  
careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Why are high-quality mirrors so expensive? new [Re: Starhawk]
      #5721285 - 03/08/13 09:53 PM

Can anyone give a good estimate of the market for amateur mirrors? How many does GSO turn out annually?

Using a production device designed to produce MILSPEC and NASA grade optics is not going to be cost effective for amateur mirrors.

Robotic arms are available used for only $25,000. A production system built around adapting more general purpose technology could be put together (soon - if not today) for a fraction of that $400,000 super-high-tech system.

Edited by careysub (03/08/13 11:14 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Starhawk]
      #5722158 - 03/09/13 11:55 AM

Quote:

So, think about this:

Mirror Machine (Dream version): $400K
Mirror Blanks (base Quality, 200mm size): $35
Consumables/ mirror: $20
Labor/mirror: $60


-Rich




Not to mention you missed the mark on the numbers and forgot a few important items.

Mirror Machine (Dream version): $400K
Support interferometer from QED $200K
Mirror Blanks (base Quality, 200mm size): $35
Consumables/ mirror: $100 MRF Fluid is expensive!
Labor/mirror: $160

MRF is not a magic bullet, there is lots of prep work just to get it ready for MRF.
Plus you still need a regular mirror lab and all that equipment.
My SMALL lab has about $150K in Strasbaugh polishing machines.

Rich proved the point but its even tougher that his guess.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: careysub]
      #5722176 - 03/09/13 12:08 PM

Quote:


Robotic arms are available used for only $25,000. A production system built around adapting more general purpose technology could be put together (soon - if not today) for a fraction of that $400,000 super-high-tech system.




Again, it's just not so easy. I've already built a semi "robotic" polishing machine for large mirrors Its a linear over arm machine much like they use at Steward Mirror Lab for the 10 meter mirrors, mine is just scaled down to 1 meter.

The software I wrote is not all that sophisticated with no intelligence, but it does follow polishing sequence scripts. Surprisingly this approach works fairly well and is very intuitive for me to write the scripts based upon optical test data. I can direct the process to push a mirror towards parabolic as well as concentrate on zones or even mix the process up so it corrects a zone while moving the over all shape of the mirror. It's pretty cool.

The problem is that the fundamental process of polishing glass is still very slow and requires people to monitor the process which equals $$$$. Speed and high quality optical surfaces are mutually exclusive.


Post Extras: Print Post   Remind Me!   Notify Moderator  
careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5722302 - 03/09/13 01:10 PM

Sounds fascinating. I would really like to see your shop someday.

I am a software algorithms/machine learning/AI guy and would like to learn more about the problems in automating.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5722311 - 03/09/13 01:14 PM

I figured that in order to make a profit and stay in business, an optician HAS to use machines to grind and polish optics before figuring them by hand, machine or both. I don't see how someone can make optics for a living by hand entirely, it seems to be just too labor intensive otherwise making telescopes for amatuer astronomers.

Taras


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Achernar]
      #5722419 - 03/09/13 02:17 PM

Quote:

I figured that in order to make a profit and stay in business, an optician HAS to use machines to grind and polish optics before figuring them by hand, machine or both. I don't see how someone can make optics for a living by hand entirely, it seems to be just too labor intensive otherwise making telescopes for amatuer astronomers.

Taras




You are correct. We do use machines for the basic polishing and most of the figuring. They are just not automated and they need not be automated as the process is VERY basic.

As of late we have made very few new mirrors from scratch. The Chinese have taken over this market but thankfully a huge number of these mirror need refiguring or finishing really. Our business has transitioned from making lots of new mirrors to almost exclusively correcting existing optics. Interestingly enough I prefer it this way. The basic grinding and polishing of the blank is messy and labor intensive and BORING for me. Adjusting the figure on existing mirrors uses very little materials and does not require my constant attention and it is an art form that I enjoy in my own twisted way.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Bob S.
Carpal Tunnel
*****

Reged: 07/14/05

Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5722542 - 03/09/13 04:05 PM

I back channeled an optician who has told me that they have rarely ever had to refigure a Synta mirror. Apparently, this is not true of other Chinese sourced manufacturers. I am glad that Synta is putting out pretty consistent mirrors. This represents an opportunity for folks on a limited budget to sometimes not have to spend a bunch of money to get a good mirror. Bob

Post Extras: Print Post   Remind Me!   Notify Moderator  
careysub
Carpal Tunnel
*****

Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: Why are high-quality mirrors so expensive? new [Re: Bob S.]
      #5722558 - 03/09/13 04:15 PM

Does Synta sell mirrors directly to the public? GSO is the only Chinese vendor selling mirrors a la carte that I know of.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: Why are high-quality mirrors so expensive? new [Re: careysub]
      #5722608 - 03/09/13 04:35 PM

Synta mirrors are available in Celestron, Sky-Watcher, Konus, Orion, and other brands of telescopes.
They are not uniformly good, however. Read David Knisely's review of his 14" from Orion to get a horror story.
That the average may be better is a good thing. They certainly make a lot of mirrors.
http://synta.en.gongchang.com/
and also see:
http://www.skywatcher.com/swtinc/index2.php


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: Why are high-quality mirrors so expensive? new [Re: Starman1]
      #5722641 - 03/09/13 04:52 PM

well here's my SW 130..again...the most important seems to turn back to spherical.



but then again my first mirror with a flash polish off a machine...



machines may increase speed, which it only took two hours to correct this but in the hands of the clueless... I'll be first in line.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Bob S.
Carpal Tunnel
*****

Reged: 07/14/05

Re: Why are high-quality mirrors so expensive? new [Re: Pinbout]
      #5722941 - 03/09/13 08:22 PM

This is what David Knisely wrote about a recent experience with a Synta mirror in late 2012. "I recently did a star test of another XX14i at the Nebraska Star Party, and it passed fairly well, so maybe what I got originally was something of a fluke. Clear skies to you."

I am not pushing Synta mirrors and the majority of my Newtonian optics have been from Zambuto, Lockwood, Spooner, Harry, Stevens, Swayze and Pegasus. I am also not an optician so rely on those folks who figure glass for a living. Just because Knisely got a bad mirror does not tell us much IMHO. However, when an optician reports to me that he has figured countless other Chinese sourced mirrors and rarely gets a Synta for refiguring, that tells me something. I guess based on what was conveyed to me, I would be inclined to try a Synta mirror before I would select one of the other brands. I too have heard sterling reports of other Chinese manufacturers making very good mirrors and do not doubt the veracity of the end-users experiences. However, an optician would seem to me to be a more authorative source for discriminating the good from the bad as they again make their livings refiguring other people's work. Bob

Edited by Bob S. (03/09/13 08:25 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
bryguy27007
super member
*****

Reged: 03/09/09

Loc: Minnesota
Re: Why are high-quality mirrors so expensive? new [Re: Bob S.]
      #5723057 - 03/09/13 10:02 PM

Here's a question. Is a refigured mirror that was originally from Synta or GSO with a new coating from a good optician in the same league as a mirror from a good optician in the first place? Or are the Bk-7 and pyrex mirrors never going to be able to preform in the same league as the premium mirrors? Is the only difference heat retention at that point?

This thread has been fascinating to follow. Cary, I would love to see your thoughts in a blog post of something of the sort that isn't censored by the forum. Seems like you are quite knowledgable in the subject.

Edited by bryguy27007 (03/09/13 10:09 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Achernar
Postmaster
*****

Reged: 02/25/06

Loc: Mobile, Alabama, USA
Re: Why are high-quality mirrors so expensive? new [Re: Cary]
      #5723152 - 03/09/13 11:15 PM

I imagine the drying up of Pyrex sheet glass might have something to do with that as well. And it makes sense to fix a mirror when a poor mirror can be turned into an excellent one. The nice thing about them, is unless some calamity befalls them, they outlast their owners and then some.

Taras


Post Extras: Print Post   Remind Me!   Notify Moderator  
Cary
Vendor (Woden Optics)


Reged: 07/07/04

Loc: Rancho Cordova, CA
Re: Why are high-quality mirrors so expensive? new [Re: Achernar]
      #5723247 - 03/10/13 12:21 AM

There is only a lack of Pyrex brand boroslicate. There is no lack of borosilcate glass. Also, very good figures can be made on BK& and soda lime glass.... my customer comments have confirmed this over the last ten years.

Post Extras: Print Post   Remind Me!   Notify Moderator  
johnnyha
Postmaster
*****

Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: Why are high-quality mirrors so expensive? new [Re: Bob S.]
      #5723256 - 03/10/13 12:27 AM

Quote:

I back channeled an optician who has told me that they have rarely ever had to refigure a Synta mirror. Apparently, this is not true of other Chinese sourced manufacturers. I am glad that Synta is putting out pretty consistent mirrors. This represents an opportunity for folks on a limited budget to sometimes not have to spend a bunch of money to get a good mirror. Bob




Bob I have heard exactly the same thing and on very good authority. So strong rumor would have it anyway, that Synta (Orion/Celestron/Sky-Watcher) has better robots...


Post Extras: Print Post   Remind Me!   Notify Moderator  
Sgt
Pooh-Bah
*****

Reged: 12/17/05

Loc: Under the southern horn of the...
Re: Why are high-quality mirrors so expensive? new [Re: johnnyha]
      #5723356 - 03/10/13 04:19 AM

Synbots - no ordinary robots!

Post Extras: Print Post   Remind Me!   Notify Moderator  
David Knisely
Postmaster
*****

Reged: 04/19/04

Loc: southeastern Nebraska
Re: Why are high-quality mirrors so expensive? new [Re: Bob S.]
      #5723389 - 03/10/13 05:29 AM

Quote:

This is what David Knisely wrote about a recent experience with a Synta mirror in late 2012. "I recently did a star test of another XX14i at the Nebraska Star Party, and it passed fairly well, so maybe what I got originally was something of a fluke. Clear skies to you."

I am not pushing Synta mirrors and the majority of my Newtonian optics have been from Zambuto, Lockwood, Spooner, Harry, Stevens, Swayze and Pegasus. I am also not an optician so rely on those folks who figure glass for a living. Just because Knisely got a bad mirror does not tell us much IMHO. However, when an optician reports to me that he has figured countless other Chinese sourced mirrors and rarely gets a Synta for refiguring, that tells me something. I guess based on what was conveyed to me, I would be inclined to try a Synta mirror before I would select one of the other brands. I too have heard sterling reports of other Chinese manufacturers making very good mirrors and do not doubt the veracity of the end-users experiences. However, an optician would seem to me to be a more authorative source for discriminating the good from the bad as they again make their livings refiguring other people's work. Bob




My problem isn't that a mirror was necessarily bad (which *does* happen even with some good mirror makers). It was that Orion claimed it "met their standards", when it clearly did not even get to the Rayleigh optical criteria of 1/4 wave! This kind of "standard" by Orion is simply poor to mediocre quality in *any* telescope mirror. Orion should know by now just what the Rayleigh and Marechal limits truly require and should have used that as their standard. Instead, the company basically "hid" behind the term "diffraction limited", which, as we all know means little if anything. If my original mirror had been exactly 1/4 wave p-v and 1/14th wave RMS wavefront, I wouldn't have said very much about the issue in my review, as I knew I wouldn't be getting a professional quality set of optics. I expected that I would probably get a mirror that would perform OK and would eventually benefit at least slightly with some refiguring work by a professional optician. However, I didn't expect that what I would get would fail *both* of the common standards for minimum mirror optical wavefront quality and would require immediate refiguring before it worked halfway close to what its aperture would normally yield. Synta let one get through that didn't meet two common standards, which happens. Orion sold the scope to me and didn't truly and precisely define a standard of optical quality. That is my beef with them. However, with Mike Lockwood's intervention, I now have optics in my scope which vastly exceeded my wildest expectations. It cost me some money, but I think it was well worth it. Clear skies to you.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Bob S.
Carpal Tunnel
*****

Reged: 07/14/05

Re: Why are high-quality mirrors so expensive? new [Re: David Knisely]
      #5723460 - 03/10/13 07:22 AM

Quote:

Quote:

This is what David Knisely wrote about a recent experience with a Synta mirror in late 2012. "I recently did a star test of another XX14i at the Nebraska Star Party, and it passed fairly well, so maybe what I got originally was something of a fluke. Clear skies to you."

I am not pushing Synta mirrors and the majority of my Newtonian optics have been from Zambuto, Lockwood, Spooner, Harry, Stevens, Swayze and Pegasus. I am also not an optician so rely on those folks who figure glass for a living. Just because Knisely got a bad mirror does not tell us much IMHO. However, when an optician reports to me that he has figured countless other Chinese sourced mirrors and rarely gets a Synta for refiguring, that tells me something. I guess based on what was conveyed to me, I would be inclined to try a Synta mirror before I would select one of the other brands. I too have heard sterling reports of other Chinese manufacturers making very good mirrors and do not doubt the veracity of the end-users experiences. However, an optician would seem to me to be a more authorative source for discriminating the good from the bad as they again make their livings refiguring other people's work. Bob




My problem isn't that a mirror was necessarily bad (which *does* happen even with some good mirror makers). It was that Orion claimed it "met their standards", when it clearly did not even get to the Rayleigh optical criteria of 1/4 wave! This kind of "standard" by Orion is simply poor to mediocre quality in *any* telescope mirror. Orion should know by now just what the Rayleigh and Marechal limits truly require and should have used that as their standard. Instead, the company basically "hid" behind the term "diffraction limited", which, as we all know means little if anything. If my original mirror had been exactly 1/4 wave p-v and 1/14th wave RMS wavefront, I wouldn't have said very much about the issue in my review, as I knew I wouldn't be getting a professional quality set of optics. I expected that I would probably get a mirror that would perform OK and would eventually benefit at least slightly with some refiguring work by a professional optician. However, I didn't expect that what I would get would fail *both* of the common standards for minimum mirror optical wavefront quality and would require immediate refiguring before it worked halfway close to what its aperture would normally yield. Synta let one get through that didn't meet two common standards, which happens. Orion sold the scope to me and didn't truly and precisely define a standard of optical quality. That is my beef with them. However, with Mike Lockwood's intervention, I now have optics in my scope which vastly exceeded my wildest expectations. It cost me some money, but I think it was well worth it. Clear skies to you.




Dave, I think your beef with Orion and also Synta on your mirror is more than legitimate. I doubt that Orion tests any or few of the scopes they receive from their manufacturers. In this case, Synta did not live up to their reputation. As you have pointed out, this even happens with professional opticians, who occassionally who put out a clunker.

However, your poor experience could lead someone to believe that Synta mirrors are inferior to brand X, Y or Z and apparently, at least one optician who is reportedly refiguring a lot of Chinese mirrors has told me that Syntas do not come into his shop very often. Apparently, another Chinese mirror maker that has made their mirrors available to the public and also does a lot of OEM work is producing many poorly performing mirrors. I would imagine that it is difficult for a company like Synta to seperate themselves from the pack. One of the things that the optician and I discussed is that many consumers have not looked through a well corrected mirror system and experienced what a high-performing Newtonian can do. If they were to put there poorly figured scope next to a better figured mirror under the same condtions, they would be able to discriminate for themselves how poorly a given mirror was performing.

I am certainly with you on your appreciation of Mike Lockwood. I have owned a 16.5" f/3.6, 28" f/3.5 and currently own and will own for the time I am in the hobby a 20" f/3 Lockwood equipped scope. In terms of why high-quality mirrors are so expensive, one just needs to look through a Lockwood or Zambuto-mirrored scope to appreciate the difference. There are other opticians capable of the same performance but I do not know if they can do it with the same consistency that the above-mentioned opticians seem to be able to do it?

Rather than keep the optician a mystery, I back channeled Cary Clebord of OWL to find out who's mirrors he was refiguring and who's he was not. He gave me permission to mention that he rarely has seen a Synta come into his shop for refiguring yet has seen hundreds/thousands of other Chinese mirrors with consistently poor figures. That to me seems like a very important and not to be disregarded piece of data. In mentioning this experience, he is not in anyway self-promoting in the sense that he is just pointing out that there is one manufacturer, Synta, that seems to be doing a more consistently good job as compared to some other Chinese-sourced manufacturers. If I wasn't hooked on Lockwood or Zambuto, and wanted a Chinese-sourced mirror, it seems that I would be improving my chances of getting a good one if I went with Synta. Obviously, unlike premium mirrors from the likes of Lockwood or Zambuto, there are less safeguards in terms of what gets out of the shop. In your case Dave, both Orion and Synta obviously let you down and that was a bit of a shame. On the positive side, you now get to experience with the Lockwood refigure, what it is like to have a "premium" mirror. Bob


Post Extras: Print Post   Remind Me!   Notify Moderator  
Joe G
scholastic sledgehammer


Reged: 01/10/07

Loc: Southern California
Re: Why are high-quality mirrors so expensive? new [Re: Bob S.]
      #5724007 - 03/10/13 02:15 PM

I just had my 16 inch Lightbridge mirror refigured by Cary. I also have an Orion XT12i bought new in 2006-07. I think that vintage was made with Pyrex.

After a spell of aperture fever, I bought the LB 16 used in 2009. After adjusting for some Naglers and Catseye tools that were included with the sale I paid about $1700 for the LB which included a Moonlite focuser and an Argo Navis system.

Over the years I hardly used the scope versus my 12 inch Orion. Part of the reason was the weight and size of the LB and the optics of the LB versus the Orion. Despite the 78% increase in mirror size, the Orion scope provided better views. Last December, I finally decided to "makeover" the LB. I had Dennis Steele of Dobstuff do his wonders and sent the mirrors to Cary/Optic Wave Labs.

I am likely not the best star tester. In side by side comparisons with these two scopes, the Orion snapped into focus more easily. The E and F stars in the trapezium were instantly visible in the Orion 12 inch, yet much harder to see in the larger LB 16 inch. Jupiter looked better as well.

Cary tested the LB mirror and said that it had a PV Error of 1/2.8 and a Strehl of 0.69. He said that it was a fairly typical Lightbridge mirror in his experience. After refiguring, it now has a PV Error of 1/8.9 and a Strehl of 0.96.

I will say that Cary's service was excellent. He responded to all emails promptly and the turnaround time was about two weeks. I just received the mirror last week and had it briefly under the stars last night and will test further over the next few days.

A question for Cary:

Of the hundreds (or thousands) of Brand X mirrors that you have refigured, what has been the satisfaction rate? With that many, I'm sure there have been a few unsatisfied customers. But I would guess that most have been exceedingly happy with the results?

In all, I can't argue with the notion that buying a used Brand X mirror for a decent price and having it tested and possibly refigured is a great way to get a great mirror at a decent overall price.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: Why are high-quality mirrors so expensive? new [Re: Joe G]
      #5724186 - 03/10/13 04:14 PM

Guys, we need to steer this away from discussions of one specific brand by a competing vendor.

We can discuss what it takes to make a high quality mirror, and any professional mirror maker who wants to contribute to that discussion is welcome.

Discussion by one mirror maker of the perceived quality of his competitors is against the TOS, so please don't ask the vendors to violate it.

Thanks,

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
acochran
professor emeritus


Reged: 06/19/08

Loc: So. CA
Re: Why are high-quality mirrors so expensive? new [Re: Joe G]
      #5724197 - 03/10/13 04:21 PM

My Lightbridge 16" mirror took Steve Swayze over 6 months to refigure, because for some reason it did not figure like a normal mirror. He believed it was not annealed properly. There are many good reviews of these scopes, but I will not buy another Lightbridge, on the chance it might need refiguring.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jarad
Postmaster
*****

Reged: 04/28/03

Loc: Atlanta, GA
Re: Why are high-quality mirrors so expensive? new [Re: acochran]
      #5724263 - 03/10/13 04:46 PM

Again, this is not the place to list complaints about various vendors or brands.

We have had several good answers about the costs of making high quality mirrors. If someone has something to add on topic, please go ahead. If this thread keeps veering off into complaints against vendor X, Y or Z I am going to shut it down.


Thanks,

Jarad


Post Extras: Print Post   Remind Me!   Notify Moderator  
nevy
professor emeritus
*****

Reged: 02/07/12

Loc: UK
Re: Why are high-quality mirrors so expensive? new [Re: Jarad]
      #5724335 - 03/10/13 05:18 PM

My lightbridge tested a bit better than 1/4 wave, I wasn't to pleased with planetary performance but after putting a protostar secondary on its now very good on the planets , and excellent on DSOs , it's a keeper.

Post Extras: Print Post   Remind Me!   Notify Moderator  
davidpitre
Post Laureate
*****

Reged: 05/10/05

Loc: Central Texas
Re: Why are high-quality mirrors so expensive? new [Re: nevy]
      #5724473 - 03/10/13 06:42 PM

It seems the question was pretty well answered.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pinbout
Postmaster
*****

Reged: 02/22/10

Loc: nj
Re: Why are high-quality mirrors so expensive? new [Re: davidpitre]
      #5724566 - 03/10/13 07:30 PM

on page 38 from zambuto usergroup Zambuto Making Mirror.doc

Quote:

Let's do an example. We're talking about industry, now, right?
Industrial shops have to get $60 as a minimum to cover labor,
overhead, benefits, insurance, etc, etc, you know how it goes. I
know of one particular mirror, for example a 15" that sells for
about $1,600.00. Let's say the blank costs $500.00, the coating
is $150.00, there is packaging at $20.00, shipping
three times for a total of $90.00. So that leaves $840.00 to grind,
polish, figure, test, and certify the mirror. It has to be
documented, handled for shipping, and so on. That pays labor
as well as materials such as grit, pitch, and cerium. Then there is
overhead- tooling, such as machinery and test equipment. There
is office- yes, paperwork. Then there is business insurance, and
so on, and so on. And we expect the optic to perform like an apo
refractor of same aperture? I'm sorry, it just isn't there. There are
not enough dollars to pay all those expenses for enough hours
to make a perfect optic.

Do you know what a real industrial (industry) shop charges for a
premium 14.5" mirror with verifiable interferometry? I know this
first hand- Over four thousand dollars, and that is a fair price. I'm
not kidding, and I'm not bull-sh---ing you. The amateur industry
doesn't have the sophistication to pay that kind of money for
reflectors because it was raised on garage opticians with no
overhead, working in their homes. "We were weaned on Coulter
optics", people. Only apo-people expect and are willing to pay the
kind of money where an industrial shop can deliver perfection.

So what I'm saying here really is, I think we need to temper our
expectations. if we get a smooth mirror with a decent (not
perfect) star test it is probably well worth the money paid. And it
will perform just fine! If you buy from some other company than
us and you happen to have a narrow turned edge, I would
happily mask it off. I would not expect it to be perfect because it
isn't going to happen in every case. If that is what has to happen,
I bet there will be fewer mirror-makers in the very near future.

I hope I didn't dig myself in too deep, here. And this "tempering"
is not a statement about our product. It is a general statement,
and my opinion, regarding reasonable expectations from the
optic industry as a whole.





Post Extras: Print Post   Remind Me!   Notify Moderator  
CosmoSat
Pooh-Bah


Reged: 07/24/09

Loc: India
Re: Why are high-quality mirrors so expensive? new [Re: Joe G]
      #5725269 - 03/11/13 05:46 AM

Quote:

I just had my 16 inch Lightbridge mirror refigured by Cary. I also have an Orion XT12i bought new in 2006-07. I think that vintage was made with Pyrex.

After a spell of aperture fever, I bought the LB 16 used in 2009. After adjusting for some Naglers and Catseye tools that were included with the sale I paid about $1700 for the LB which included a Moonlite focuser and an Argo Navis system.

Over the years I hardly used the scope versus my 12 inch Orion. Part of the reason was the weight and size of the LB and the optics of the LB versus the Orion. Despite the 78% increase in mirror size, the Orion scope provided better views. Last December, I finally decided to "makeover" the LB. I had Dennis Steele of Dobstuff do his wonders and sent the mirrors to Cary/Optic Wave Labs.

I am likely not the best star tester. In side by side comparisons with these two scopes, the Orion snapped into focus more easily. The E and F stars in the trapezium were instantly visible in the Orion 12 inch, yet much harder to see in the larger LB 16 inch. Jupiter looked better as well.

Cary tested the LB mirror and said that it had a PV Error of 1/2.8 and a Strehl of 0.69. He said that it was a fairly typical Lightbridge mirror in his experience. After refiguring, it now has a PV Error of 1/8.9 and a Strehl of 0.96.

I will say that Cary's service was excellent. He responded to all emails promptly and the turnaround time was about two weeks. I just received the mirror last week and had it briefly under the stars last night and will test further over the next few days.




You were comparing a f/4.5 mirror with a f/5 one..
Have you had the 12" tested too?
It would be interesting to hear from you about the views through the newly refigured mirror.

Clear Skies!


Post Extras: Print Post   Remind Me!   Notify Moderator  
estwing
member


Reged: 02/24/13

Re: Why are high-quality mirrors so expensive? new [Re: CosmoSat]
      #5725499 - 03/11/13 10:13 AM

just had mine from nichol optics with hi-lux coatings by orion optics in the U.K.report says 1/8 P.V.strehl0.95..£1600 F3.9 18"

Post Extras: Print Post   Remind Me!   Notify Moderator  
BluewaterObserva
Postmaster
***

Reged: 05/18/04

Re: Why are high-quality mirrors so expensive? new [Re: Dragonwatcher]
      #5726565 - 03/11/13 06:33 PM

Sorry, I did not mean it come off like anything negative.

I used to think the same thing so I tried to make two 12.5" mirrors. Taught me a serious lesson. I since resigned myself to buying completed optics only.


Post Extras: Print Post   Remind Me!   Notify Moderator  
John Huntley
scholastic sledgehammer
*****

Reged: 07/16/06

Loc: South West England
Re: Why are high-quality mirrors so expensive? new [Re: estwing]
      #5726639 - 03/11/13 07:14 PM

Quote:

just had mine from nichol optics with hi-lux coatings by orion optics in the U.K.report says 1/8 P.V.strehl0.95..£1600 F3.9 18"




Those are very decent figures for an F/3.9

My OO 12" F/5.3 Zygo report reads 1/8.9th wave PV and a strehl rating of .987. It's performance is superb when the UK seeing allows


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | 3 | 4 | 5 | (show all)


Extra information
24 registered and 31 anonymous users are browsing this forum.

Moderator:  ausastronomer, Phillip Creed, JayinUT, okieav8r 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 4635

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics