25 replies to this topic

[Optics Patent]

I don't recall when they changed the secondary mirror spot from the forward surface of the corrector to the rear.  Maybe it was when they changed from Cave to Cumberland to supply the optics, or maybe in 1964 when lots of other changes were implemented.

 

When observing earlier this week my 1962 let me focus sharply on Sirius, while at the same time showing a big out of focus blob of the star (all nice and concentric).  I was mystified, and then focused about 12 turns in (very approximate as it was dark and it was cold and I was going by feel.)  That focused the blob to a much brighter star image, as the other star image defocused and disappeared.

 

Can you guess what I was seeing?  (Vintage owners won't need to guess).

 

That dim but sharp star image was the reflection off the unreflectorized first surface of the corrector.  Even a couple percent reflectivity of the glass coatings was enough to generate a star image of such a bright star (but not enough to worry about reducing contrast).

[petert913]

Yes, I can't imagine why they would ever have aluminized the outside surface of the corrector.   Not good for a couple of reasons.  Reflection, as you mention,  and exposure to the elements. 

[NC Startrekker]

Yes, I can't imagine why they would ever have aluminized the outside surface of the corrector.   Not good for a couple of reasons.  Reflection, as you mention,  and exposure to the elements. 

I understand that the secondary spot was originally placed on the outside vice the inside surface of the corrector to avoid a potential patent infringement from an existing Maksutov design. 

[Codbear]

I understand that the secondary spot was originally placed on the outside vice the inside surface of the corrector to avoid a potential patent infringement from an existing Maksutov design. 

That's pretty ironic, given Ben's profession! 

[Optics Patent]

And I have searched in vain trying to find that patent that people speak of.

[DAVIDG]

With the spot on the front surface that is why these optics had the rear surface of the corrector MgF2 coated but not the front.  I believe they changed the design to the rear spot system around 1964. 

  The patent your looking for may have been issued in  Europe for  Maksutov's design that I believe was  granted  around 1946.  The designer of the Questar optics I'm sure knew of the Maksutov  patent and didn't want to interfere with it. John Gregory also published his design both in Sky and Telescope and the Optical Journal of America in 1957.  I know from my own patents that once the information is  in the public domain you can not  go back and patent an idea but Questar may have assumed that a patent was filed before the  public disclosure of the Gregory design so wanted to be sure that they had freedom to operate. 

 

                  - Dave 

[Optics Patent]

With the spot on the front surface that is why these optics had the rear surface of the corrector MgF2 coated but not the front.  I believe they changed the design to the rear spot system around 1964. 

  The patent your looking for may have been issued in  Europe for  Maksutov's design that I believe was  granted  around 1946.  The designer of the Questar optics I'm sure knew of the Maksutov  patent and didn't want to interfere with it. John Gregory also published his design both in Sky and Telescope and the Optical Journal of America in 1957.  I know from my own patents that once the information is  in the public domain you can not  go back and patent an idea but Questar may have assumed that a patent was filed before the  public disclosure of the Gregory design so wanted to be sure that they had freedom to operate. 

 

                  - Dave 

In my experience, no business assumes that patent rights prevent them from pursuing a desirable design unless there is compelling proof of the patent rights.  This is still a mystery to me.  A patent in a European nation would have no effect on the US market and would affect only their ability to sell into that particular country.

 

Regrettably, I have been unable to locate the Gregory article (Gregory, John F. (March 1957), "A Cassegrainian-Maksutov Telescope Design for the Amateur", Sky and Telescope, vol. 16 no. 5, pp. 236–240).

I'm eager to hear any scraps of info to help resolve this mystery.

[DAVIDG]

"In my experience, no business assumes that patent rights prevent them from pursuing a desirable design unless there is compelling proof of the patent rights."

   In my business of industrial  research we do extensive patent searches to be sure we have the right to operate before we take on project.  There have been a number of times were there have been gray areas were our lawyers felt there might be an issue so we have not pursued that project. 

  It looks like Maksutov was issued a patent in Europe and Gregory did have two articles about his design. Being back in 1957 without the ability to easily do a patent search, maybe the simplest answer was to redesign the optics so there was no chance of a patent violation vs risking it and wind up bankrupting a small company just starting out in a  legal fight.  Perkin Elmer was a big company so I'm sure Questar didn't want to take them on if they had any rights to the  Mak design with the spot on the back of the corrector.   Look what happen to Criterion when Celestron took them to court over the how they made their correctors. It wasn't long after that they went under.   

   I know two individuals that knew John Gregory well and were also in the optical business so I'll ask what they may know.

 

                      - Dave 

[Optics Patent]

Please do check your contacts. 

Patent searching has been around for centuries (there is a library in every state) and I agree that when there is a patent, the scope can be debatable and cause to avoid.  But when there simply is no evidence of a patent, I've never seen a business that will use a second choice design on the chance that an unknown patent might exist. 

 

I confess that I don't have ready means to search for German patents, but I have searched Perkin Elmer's and found nothing pertinent.

[DAVIDG]

  Ben,

    I think the lawyer for Questar who was Denny did a patent search and saw a number of designs by Frank G Back. Back may have licensed them to Perkin Elmer. The story goes that Denny wanted away to get around some patent(s) and envision putting the spot on R1 to get around "the patent(s)". Again I think what he found was the Back designs. Here is an example that might have caused issues https://patents.goog...k G Back&page=3

 

              - Dave  

Edited by DAVIDG, 08 March 2019 - 06:35 PM.

[Optics Patent]

Thanks for the link. That narrowly drafted patent would not be infringed by anything Questar ever made. It’s limited to a flat spot in the middle of the corrector for the secondary in claim 1, and. But I’ll dig around in case it leads to something else.

Edited by Optics Patent, 09 March 2019 - 06:32 AM.

[mconsidine]

Back had a patent after this one that specifically put the spot on R2 of the corrector.

MattC

[Optics Patent]

Back had a patent after this one that specifically put the spot on R2 of the corrector.

MattC

I'm afraid the patent database doesn't find anything else related to this. 

 

This one looks something like the 700 lens (except the main mirror is front surface reflection not Mangin).

 

My best hypotheses are that the early R1 secondary was not for patent reasons, or was not based on good patent advice.

Edited by Optics Patent, 09 March 2019 - 03:08 PM.

[mconsidine]

No.

See patent 2701983, second to last page, last paragraph in column on the left.

https://patents.goog...sort=old&page=1

 

PS there was one other patent the following year for a catadioptric.  But this is the one with the specific claim re: the spot being on R2

Edited by mconsidine, 09 March 2019 - 07:42 AM.

[Optics Patent]

I did review that. Its claims include the negative rear auxiliary lens system like the 700 has so it would never have affected Questar’s right to use the R2 secondary.

In my confident professional opinion these patents are literally worthlessly narrow and were probably obtained not for commercial benefit but perhaps simply as some kind of public disclosure.

[mconsidine]

Ah, but what matters is the advice their lawyer gave them at the time.

Cheers,

Matt

[DAVIDG]

Ah, but what matters is the advice their lawyer gave them at the time.

Cheers,

Matt

 Exactly. All I can say in my line of work  even if  your right on  a patent issues it cost a very large amount of money to prove it if your challenged in court.  I know of a couple cases for my company that took over 10 years to win and  cost many  hundreds of thousands in legal costs even though a team of lawyers wrote the patent saying to was bullet proof yet another team thought they had a case.   So I can see Denny doing a patent search  and  not being  an optical expert finding a number of patents that he thought might be an issues for Questar.  So  he tellings Questar to redesign the optics to make them unique enough to reduce the risk of getting into a patent fight.  If  you read the Company 7 history about Questar, they waited until 1965 to change the optical design to avoid some patent(s) they felt could cause a problem and these Frank Back patents might have been the ones along with Maksutov's patent in Europe. 

 

                          - Dave

[NC Startrekker]

Ben, could it be that you are reviewing the situation through the eyes of a 21st century patent attorney instead of a late 1940's one? Alternately, it may be explained more by Braymer's risk tolerance. He may have simply found it easier to modify the design slightly and run no risk of challenge. Having just completed my taxes, I can relate to the latter. I likely overpay taxes every year just to avoid any potential of an IRS challenge, regardless of whether I would likely be found in the right or not. Though this kind of thinking is probably foreign territory for a lawyer. 

[mconsidine]

According to discussion over on the Antique Telescope Society forum, it was the Bouwers (Netherlands) patent filed in 1941 that was believed to be the issue.

Matt

[Optics Patent]

Thanks for the good info!

 

A patent in any other country would have no effect on a US company's ability to make and sell products in the US or other countries.

 

It's unimaginable that Questar would adopt a second-choice design to be able to access the Netherlands market of the 1950s with their standard design.

 

That said, Mr. Bouwers was a prolific inventor, as my patent search shows.

 

I'd be willing to consider a risk-averse business strategy if there were an actual US patent we could find as potentially pertinent.  Since the US patent system was implemented centuries ago, there has never been a reason for a business to adopt an inferior design when there was no patent to worry about.  I've been looking for such a a patent, and welcome all the clues to help find the truth amidst the mythology. 

 

One good place to find a patent that the inventor/owner thought was pertinent to his decision making (especially a patent that stymied his plans) is in the patent citations in the patents he filed.  Here are Braymer's.  You can click each title, then click on "patent citations" to find the pertinent patents.  Bouwers does appear, but nothing that would cover the R2 secondary.

Edited by Optics Patent, 10 March 2019 - 11:39 AM.

[DAVIDG]

 As Matt pointed out there is a discussion on the Antique Telescope Society forum about the Questar  patent issue. As Matt points out,  Braymer was concerned with the Bouwer's patent and the information on ATS forum states he meet with him to try to licence it. This information is from a person that wrote a bio of Questar using information from their records and talking with the Braymers wife. So even thou the Bouwer's patent may not have caused  a legal issue in the US market, it looks to be the reason why Braymers went with the alternate design.  You can join the ATS forum and read the thread which has more details https://ats-forum.gr....io/g/ATS-Forum

 

                       - Dave 

[Optics Patent]

Dave, after a good exhange of info at that helpful group, I have found what I believe is the patent that forced the R1 secondary location.

 

https://patents.goog...atent/US2504383

 

Fig. 4 shows the key variant “in which a compound lens is employed in the objective and in which the collecting mirror is formed on one of the surfaces of the compound lens adjacent the ocular”.

 

This supports claim 1:

 

1. A telescope comprising
 

a concave spherical main mirror having a central aperture and having an optical axis centered in said aperture,

 

a refractive correcting element having spherical outer surfaces centered about the axis of said main mirror and positioned to intercept and refract rays of light before they strike said main mirror to correct for spherical aberration in said main mirror,

 

a collecting mirror centered about the axis of said main mirror and positioned to intercept and reflect light rays directly reflected by said main mirror without passing through said refractive correcting element,

 

an opaque optical tube fitting in said aperture in said main mirror and extending towards said collecting mirror a distance sufficient to prevent the direct access of light from said correcting element through said aperture, and

 

an ocular comprising an optically refractive system for receiving light rays reflected from said collecting mirror through said optical tube to permit an observer to view the image on said collecting mirror formed by said refractive element and said main mirror.

 

And in my opinion claim 1 covers the R2 version of a Questar scope but not the R1 early variant.  Questar's patent attorney Denny did just as I would, it appears: advise his client on how to "design around" a patent by understanding it's limitations and avoiding one of them.

 

The patent would have expired April 18 1967 (17 years after grant), and my understanding is that the R2 design was implemented well before then.  Given the actual 1961 transition, we might presume that a license was obtained earlier, and I’m interested in knowing details.

 

I note that this patent was cited in three of Braymer’s own patent applications.

Edited by Optics Patent, 12 March 2019 - 09:03 AM.

[Mr. Krabappel]

I never even knew there was such a thing as a Google patent search engine.

Interesting.

[DAVIDG]

 Ben,

   I believe the change from  the R1 to R2 design happened after 1961 and I believe it was around 1965.  On a slightly different note, the discussion  on the ATS forum  has also reinforced the fact that Cumberland was aspherizing the optics. It has been a common belief that Maks use all spherical system, including Questars. While they will work well  when the F-ratio is slower then F/15, to get the very best performance with a f/15 or faster system, a surface should be aspherized to 1) reduce or eliminate any fabrication errors and 2) remove high order spherical aberration. This is done by hand and takes time ie also money.  This is why Questar optics perform so well.  We can thank Cumberland optics for hand matching each set vs just figuring them to spheres and saying " good enough".

 

                - Dave 

[JREnglar]

FWIW my 1964 Standard is R1 and my 1968 Duplex is R2. 

 

JR