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Sky-Watcher Policy Statement on Telescopes containing ED Glass

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15 replies to this topic

#1 skyward_eyes

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Posted 13 February 2018 - 04:10 PM

Sky-Watcher worldwide is making changes on how we market and list our ED based refractors. This speaks for all ED based refractor systems moving forward.

 

See the official statement below: 

 

Sky-Watcher Policy Statement on Telescopes containing ED Glass

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Sky-Watcher will not always state the types of glass and glass combinations used in their various APO telescope designs. We ask for your understanding in this regard because it is through this confidential design and manufacturing information, arrived at with skill and extensive research, which makes our products so successful. As always we would prefer the performance of any particular Sky-Watcher telescope to speak for itself.


Edited by skyward_eyes, 13 February 2018 - 04:30 PM.

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#2 NiteGuy

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Posted 13 February 2018 - 04:37 PM

In reality, that statement makes a huge amount of sense. In reality, that statement also makes it much more confusing for customers to differentiate one model APO from another within a manufacturer's product line. Bottom line is, are customers going to accept this kind of brevity when purchasing quality scopes at this level of cost?

 

Personally, I always feel more comfortable when I have all the details, on everything, regardless of the cost, but that's just me. That said, I also know that, all the details in this particular case (APOs), might not be truly understood even by an optical expert. Just knowing that an objective has FPL-53 or whatever, certainly doesn't tell the whole story. It just says that more was spent on glass and that's meaningless without engineering the proper selection and mix of glass choices to make everything work together as a superior product. It's a conundrum. I suppose, if I had to make a choice, by the smallest of margins I'd side with Sky-Watcher on this one.


Edited by NiteGuy, 13 February 2018 - 04:46 PM.

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#3 NEOhio

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Posted 13 February 2018 - 04:59 PM

This is where a lot of companies use trade names. Designate a particular proprietary glass as, say, SW-53, and if a scope using that glass gets a good reputation then when a new scope model is sold which is advertised as having SW-53 glass then the buyer knows it is the same kind of glass as in that earlier scope. OTOH if Skywatcher then comes out with some other scope that is not advertised as having SW-53 glass then the buyer is forewarned that it is some other type of glass. No proprietary information released, but the buyer is informed. 


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#4 skyward_eyes

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Posted 13 February 2018 - 05:16 PM

We understand that a very large percentage of the astronomy market are the type of people who want all the details and we sympathize with them.

However, in order for us to remain competitive a great deal of research has gone into matching different lens elements produced of different glasses to achieve the best possible performance at the lowest possible price. By stating the glass types, we are essentially giving away our competitive advantage as such we no longer wish to make the glass materials used public. This information is our intellectual property and important to keep from our competitors.

 

We will continue to strive to innovate, giving you high quality products and a constant level of quality, for very competitive prices.
In the not too distant future we hope to provide test images and independent test results so our customers can have objective information about our products.


Edited by skyward_eyes, 13 February 2018 - 05:30 PM.

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#5 coopman

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Posted 13 February 2018 - 08:20 PM

Whatever SW has been doing, it has proven successful (so don't change!). Your refractors have objectives with high quality glass and have proven themselves to be great performers.
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#6 ianatcn

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Posted 14 February 2018 - 05:47 AM

We understand that a very large percentage of the astronomy market are the type of people who want all the details and we sympathize with them.

However, in order for us to remain competitive a great deal of research has gone into matching different lens elements produced of different glasses to achieve the best possible performance at the lowest possible price. By stating the glass types, we are essentially giving away our competitive advantage as such we no longer wish to make the glass materials used public. This information is our intellectual property and important to keep from our competitors.

 

We will continue to strive to innovate, giving you high quality products and a constant level of quality, for very competitive prices.
In the not too distant future we hope to provide test images and independent test results so our customers can have objective information about our products.

Independent test results and images will allow everyone to see how well a particular design works.  This has to be good for everyone. Televue, AP, Takahashi and other top brands do not to my knowledge ever divulge glass types. I have a real problem convincing otherwise knowledgeable amateurs that just because a telescope contains fpl53 it does not automatically make it a better telescope. I support this move by Sky Watcher and hope that other manufacturers adopt a similar approach of showing test results and images taken through the optics to speak for themselves.


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#7 Jon Isaacs

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Posted 14 February 2018 - 06:16 AM

Televue, AP, Takahashi and other top brands do not to my knowledge ever divulge glass types.

 

 

TeleVue doesn't but I believe that Astro-Physics does and I believe that Takahashi does, at least regarding the type of ED glasses used. 

 

https://www.astromar...&news_id=&page=

 

jon



#8 ianatcn

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Posted 14 February 2018 - 09:38 AM

 

Televue, AP, Takahashi and other top brands do not to my knowledge ever divulge glass types.

 

 

TeleVue doesn't but I believe that Astro-Physics does and I believe that Takahashi does, at least regarding the type of ED glasses used. 

 

https://www.astromar...&news_id=&page=

 

jon

 

Jon,

 

I don't think I have ever seen anything more than a statement of the low dispersion element.  I certainly cannot remember seeing mating elements being described. Certainly not in enough detail to work out how a lens will perform.  It is like saying that a lens contains premium glass from a specific supplier and overlooking a poor polish on the elements or poor figure. Give me test results anytime.



#9 Riccardo_italy

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Posted 14 February 2018 - 11:13 AM

First, I really appreciate Skywatcher for being part of Cloudynights and for telling us why they have decided not to disclose anymore the glass combination of their ED refractor.

 


 

However, in order for us to remain competitive a great deal of research has gone into matching different lens elements produced of different glasses to achieve the best possible performance at the lowest possible price. By stating the glass types, we are essentially giving away our competitive advantage as such we no longer wish to make the glass materials used public.

 

However I do not understand this statement. Any producer - and even some talented amateur - can purchase a SW 150 ED, disassemble it, takes measures of the radii of the two elements and measure the glass dispersion numbers.

 

A quick search on google resulted in a scientific paper of January 1944 titled: "Measurement of the refractive index and dispersion of optical glass for control of product"

http://nvlpubs.nist....32n1p39_A1b.pdf

 

So, since at least 74 years, anyone can reverse engineer a doublet refractor, provided that he has access to the right equipment.

 

EDIT: unless, of course, Skywatcher has entered the glass market and has produced a new low dispersion glass, not in the standard catalogues. But for me this is unlikely.


Edited by Riccardo_italy, 14 February 2018 - 11:16 AM.

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#10 Daniel Mounsey

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Posted 15 February 2018 - 12:35 AM

First, I really appreciate Skywatcher for being part of Cloudynights and for telling us why they have decided not to disclose anymore the glass combination of their ED refractor.

 


 

However, in order for us to remain competitive a great deal of research has gone into matching different lens elements produced of different glasses to achieve the best possible performance at the lowest possible price. By stating the glass types, we are essentially giving away our competitive advantage as such we no longer wish to make the glass materials used public.

 

However I do not understand this statement. Any producer - and even some talented amateur - can purchase a SW 150 ED, disassemble it, takes measures of the radii of the two elements and measure the glass dispersion numbers.

 

A quick search on google resulted in a scientific paper of January 1944 titled: "Measurement of the refractive index and dispersion of optical glass for control of product"

http://nvlpubs.nist....32n1p39_A1b.pdf

 

So, since at least 74 years, anyone can reverse engineer a doublet refractor, provided that he has access to the right equipment.

 

EDIT: unless, of course, Skywatcher has entered the glass market and has produced a new low dispersion glass, not in the standard catalogues. But for me this is unlikely.

 

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#11 Benach

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Posted 15 February 2018 - 02:42 AM

@Skyward eyes: I highly appreciate that you are coming to this forum. However,apart from the thoughts I share with Riccardo_Italy, I would like to see spot diagrams and MTF curves from the optical systems of various brands. This does not disclose any optical intellectual property but this makes comparisions so much easier.
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#12 Jon Isaacs

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Posted 15 February 2018 - 02:19 PM

Sky-Watcher will not always state the types of glass and glass combinations used in their various APO telescope designs.

 

 

In a thread in the refractors forum on this topic, Spongebob brought up the point that this simply says that Skywatcher will no longer have a policy of always stating the types of glasses and glass combinations used.  

 

This does not necessarily mean that they will never state the glass types and combinations used, it just means they will not provide that information 100% of the time.  

 

My guess is things will go along as before with the ED-80, ED-100, ED-120 as well as the Esprit series but that for this new 6 inch ED refractor, they will not release the glass combinations used.  

 

I think that's a reasonable decision.  No one is expecting the fanciest glass combinations in the ED-150, it's an affordable scope and they're working hard to give us the most value for our money.  At the projected price point, this is as much as can be expected. They worked some magic with the ED-120. we'll see what they can do with the ED-150.

 

Jon


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#13 Benach

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Posted 15 February 2018 - 05:42 PM

I do not care about the glass combinations they are using as long companies provide independent metrics that are easy to read, user independant and does not ruin the work of optical engineers. Spot diagrams and MTF curves, the focal plane illumination, distortion plots, in case of refractors also the color crossings etc. do not ruin anything and make comparisons very easy.

 

For those who are not able to read these, books such as Telescope Optics, Evaluation and Design are and otherwise the astrocommunity is usually happy to provide the explanation and of course there is this forum and other fora to help others.

Let me give an example: Until a couple of years ago, nearly no amateur was able to use an interferometer, let alone build and interpret the data. Nowadays Bath interferometers are almost common and software is available free of charge.

 

To make a long story short: Skywatcher and all those other companies: what do you have to lose to provide the data above?


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#14 nicknacknock

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Posted 16 February 2018 - 01:59 AM

Thread re-opened for posts.

 

Kindly remember the rules of the vendor forum and for anybody feeling up to discussing the pros and cons of this decision, you are all welcome to go to the relevant thread in refractors.

 

For the time being, please restrict your responses to remain strictly in line with the rules of this forum.



#15 skyward_eyes

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Posted 16 February 2018 - 02:03 AM

Stating one piece of glass used in a complete system does nothing to state the overall quality of the insturment. Just because we are no longer stating glasses does not mean we are cheapening the product. We have many things in development that this policy covers moving forward.

Honestly, if someone wants to reverse engineer a system they are going to do it anyway regardless of if we state the glass or not. Stating the glass does nothing to give away the entire formula. The figure, prescription and coatings are actually more vital than the type of glass used. Glass is only one factor of the entire system.

Regardless the policy is set in place. Some people understand and others don’t. We expected this to occur once the decision was made. We will continue to produce and sell our equipment with new methods of marketing to tell the complete story of the Insturment. In hopes that our new methods will actually tell the story better than simply stating glass.

If our policies do not fit your criteria when purchasing your next scope, I am sure you will find what you’re looking for from many of the other excellent and reputable companies. But we will continue to make the best equipment we can and provide the best support we can provide to those who continue to work with us.
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#16 nicknacknock

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Posted 16 February 2018 - 03:00 AM

I myself have had a few SW telescopes in the past (3 Maks, 4 Refractors). For the money I paid I was quite happy and did not expect more than what I got. I note that SW is very quick to respond to customer issues which is very important as a consideration when a purchase is made. It's not just what you are buying, it's also what support you get if something is wrong.

 

I personally disagree with this policy because, well, you stated the reasons above! Anybody can reverse engineer, any optician can derive the glass types and since "Stating one piece of glass used in a complete system does nothing to state the overall quality of the instrument", then why not state it?

 

But while I disagree, I understand that this is the policy you want to have in place and I respect it. It is not up to me to tell you how to do business as the law of supply and demand is what decides in the end.

 

While I do not currently own SkyWatcher products, I am quite open to purchasing in the future - specifically the SW180 Mak if I ever move out of town (5 years to go!) and build an obsy and start doing lunar imaging. I have had great luck with the optics in 102mm, 127mm and 150mm SW Maks. In fact, the 102mm was stupidly well corrected and I regret passing it on to a friend ever since I did so.

 

I do hope however that this thread as well as the other one in refractors is brought to the attention of the corporate structure of SW for consideration.




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