Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Dynamax 8 image compared .

  • This topic is locked This topic is locked
64 replies to this topic

#51 starman876

starman876

    Nihon Seiko

  • *****
  • Vendors
  • Posts: 20,572
  • Joined: 28 Apr 2008
  • Loc: VA

Posted 15 February 2020 - 12:23 PM

that is because that is a 4"  The ruler starts at 1" on the left and ends on 5" on the right.

 

5" minus 1" = 4" 


 

#52 tim53

tim53

    Voyager 1

  • *****
  • Posts: 14,571
  • Joined: 17 Dec 2004
  • Loc: Highland Park, CA

Posted 15 February 2020 - 12:27 PM

Looked through an 8001 many years ago and no B&L did not fix the issue. They would have been better off subcontracting Celestron to make them. All they did was add the word pro and change a 0 to a 1. So the myth continues...

This is something I've suspected for years, but have no proof of.  I've only seen a handful of these come up for sale on ebay (usually far from me), and usually for high asking prices.  And I've not been willing to take a chance that B&L may have finally gotten them right, and subsequently, suddenly quit making them.  That just doesn't make sense.

 

-Tim.


 

#53 tim53

tim53

    Voyager 1

  • *****
  • Posts: 14,571
  • Joined: 17 Dec 2004
  • Loc: Highland Park, CA

Posted 15 February 2020 - 12:32 PM

And further:  Why didn't Criterion just make a deal with Celestron and pay them a royalty for using their method?  Like when Celestron paid Meade a royalty for using level north (or whatever their term was for it)?

 

-Tim.


 

#54 markb

markb

    Viking 1

  • *****
  • Posts: 500
  • Joined: 16 Jun 2006
  • Loc: Long Island; in transition to Arizona

Posted 15 February 2020 - 02:16 PM

Off topic, but Celestrons wiped level/north out of the Nexstar HC firmware update after they lost. They may have paid damages, I never paid attention. It is a reason some folks keep early firmware in their HCs. I like the replacement even if startup is no longer fun to watch.

 

It would be interesting to hear how Meade bypassed the master plate corrector patent with an alternative procedure, or whether they licensed it, to avoid infringement suits, I assume someone knows. A google search was not helpful, but Google searches have been less useful since they monetized them.

 

EDIT: Using Terra's hint on sticking to this forum, a CN search found a post by DavidG last August referencing Meade's use of the 'classic vacuum pan method'. It was also interesting that he mentioned that Meade put half of the figure on each side of the corrector, and used thicker glass. I'll have to try verifying that with a known quality flat after I unpack months from now; curiosity only as Dave's word is good enough for me. I do remember the corrector being thicker, at least without a side by side comparision to my GPS11.

 

Interesting topic beyond the Dynamax/B&L/8001& Pro discussions. Very interesting. But, alas, my 6000 remains an expensive boat anchor for now. Wait, can't use it for that with the paper/??? tube.


Edited by markb, 15 February 2020 - 06:21 PM.

 

#55 Terra Nova

Terra Nova

    ISS

  • *****
  • Posts: 21,254
  • Joined: 29 May 2012
  • Loc: Middle Earth

Posted 15 February 2020 - 05:13 PM

It would be interesting to hear how Meade bypassed the master plate corrector patent with an alternative procedure, or whether they licensed it, to avoid infringement suits, I assume someone knows. A google search was not helpful, but Google searches have been less useful since they monetized them.

Someone here does know. I distinctly remember a discussion of such and I’m pretty sure it was in this forum several years ago. Being in my dotage, I don’t remember the details but it’s here somewhere. 


 

#56 davidc135

davidc135

    Viking 1

  • -----
  • Posts: 777
  • Joined: 28 May 2014
  • Loc: Wales, UK

Posted 17 February 2020 - 09:48 AM

I believe it's the vacuum pan method.  David


 

#57 DAVIDG

DAVIDG

    Cosmos

  • *****
  • Posts: 9,245
  • Joined: 02 Dec 2004
  • Loc: Hockessin, De

Posted 17 February 2020 - 10:29 AM

I believe it's the vacuum pan method.  David

 I have heard that  Meade used the vacuum pan method as well and it makes sense from what I have seen when testing them  Meade correctors are thicker than Celestron's and they have the Schmidt curve on  both sides, at least the ones I have tested. That makes sense if they are using the vacuum pan method. The thicker glass is less likely to break  under  vacuum but since it is thicker it is more difficult to deflect it enough to the correct depth to put the full correction on one side. Less deflection under vacuum means the Schmidt curve is weaker on that side then what is needed so to solve that, you put   the Schmidt curve of both sides but with 1/2 the power needed. That also solves another problem in that if your glass is not very optically flat to start with your grinding and polishing both side so it doesn't matter. 

   Here is  a link to how to make a Schmidt corrector using the vacuum pan method and putting the corrections on both side. I meet  author  at Stellafane a few years ago. Very nice guy who also told me some of  the tricks. One is that is you fill the vacuum pan with water that was boiled. That is  an old chemist trick that removes the dissolved air and the water supports the glass when you grind it so it doesn't flex. http://www.considine...pfaff/pfaff.htm

 

                                                 - Dave 


 

#58 Terra Nova

Terra Nova

    ISS

  • *****
  • Posts: 21,254
  • Joined: 29 May 2012
  • Loc: Middle Earth

Posted 17 February 2020 - 10:45 AM

 I have heard that  Meade used the vacuum pan method as well and it makes sense from what I have seen when testing them  Meade correctors are thicker than Celestron's and they have the Schmidt curve on  both sides, at least the ones I have tested. That makes sense if they are using the vacuum pan method. The thicker glass is less likely to break  under  vacuum but since it is thicker it is more difficult to deflect it enough to the correct depth to put the full correction on one side. Less deflection under vacuum means the Schmidt curve is weaker on that side then what is needed so to solve that, you put   the Schmidt curve of both sides but with 1/2 the power needed. That also solves another problem in that if your glass is not very optically flat to start with your grinding and polishing both side so it doesn't matter. 

   Here is  a link to how to make a Schmidt corrector using the vacuum pan method and putting the corrections on both side. I meet  author  at Stellafane a few years ago. Very nice guy who also told me some of  the tricks. One is that is you fill the vacuum pan with water that was boiled. That is  an old chemist trick that removes the dissolved air and the water supports the glass when you grind it so it doesn't flex. http://www.considine...pfaff/pfaff.htm

 

                                                 - Dave 

Interesting Dave, thank you. I wonder if the current Celestron and Meade SCTs made by Synta and Sunny still follow the two different methods and glass thicknesses as the old American-made ones or if they are now identical? I’ve read that there was a lot of collusion between the two China-based companies in recent years, hence the new lawsuit brought against Meade and its bankruptcy declaration.


 

#59 Augustus

Augustus

    Fly Me To The Moon

  • *****
  • Posts: 8,643
  • Joined: 26 Dec 2015
  • Loc: Stamford, Connecticut

Posted 17 February 2020 - 11:16 AM

Interesting Dave, thank you. I wonder if the current Celestron and Meade SCTs made by Synta and Sunny still follow the two different methods and glass thicknesses as the old American-made ones or if they are now identical? I’ve read that there was a lot of collusion between the two China-based companies in recent years, hence the new lawsuit brought against Meade and its bankruptcy declaration.

Pretty sure the newer Meades are thinner and must use master blocks.


 

#60 Terra Nova

Terra Nova

    ISS

  • *****
  • Posts: 21,254
  • Joined: 29 May 2012
  • Loc: Middle Earth

Posted 17 February 2020 - 11:33 AM

Pretty sure the newer Meades are thinner and must use master blocks.

 

I had a newer 6” Meade for a while and also an older 10” Meade, but not at the same time, nor at the time that I had either of my C8s so I was unable to make a direct comparison, however now that you mention it, the much older 10” did seem to have a thicker corrector plate. That scope Was a heavy sucker! It wore out its welcome pretty soon. Not because it didn’t give great views as it did, Jupiter was amazing in it, but mounting and dismounting it was nerver-wracking! I was always afraid I would drop it in the process. In retrospect, it was probably the best SCT I ever had out of the five that have passed thru over the years. I just had the OTA (MCOG) but I think it was an LX3?

Attached Thumbnails

  • A43BCBC2-3DBB-46B6-A4C1-70947F6A987F.jpeg

 

#61 markb

markb

    Viking 1

  • *****
  • Posts: 500
  • Joined: 16 Jun 2006
  • Loc: Long Island; in transition to Arizona

Posted 17 February 2020 - 11:40 AM

There is no reason for Meade not to have made the change at some point after the Celestron owned patent expired unless they chose to continue the vacuum pan method for tooling expense reasons or preference for the results of that method.

 

I would assume that the movement to Chinese maufacturing facilities let both Meade and Celestron make whatever manufacturing method changes they wanted for new facilities, or to assume use of any methods already in use in China, if existing facilities were used. A quick flat test should at least determine if the Chinese made Meade correctors are double side figured, but Augustus's thickness estimate likely indicates they went to the master block method.

 

I have to take an IP (Intellectual Property law) course after I relocate!


Edited by markb, 17 February 2020 - 11:51 AM.

 

#62 DAVIDG

DAVIDG

    Cosmos

  • *****
  • Posts: 9,245
  • Joined: 02 Dec 2004
  • Loc: Hockessin, De

Posted 17 February 2020 - 11:47 AM

 I have been doing industrial research for 36 years now. There are two  driving forces to it. 1) solve a problem 2) once solved do it as cheaply as possible to MAKE MONEY.  I'll toot my own horn a bit. A product I help developed which is a clear material used  in Solar panels just won award. https://www.pv-magaz...gazine-awards/  The same process went into the devolpment of the clear film, ie figure out how to do it, then figure out how to do it as cheaply as possible. 

 So the same rules apply in  making telescopes or in this case corrector plates. Celestron developed the Master Block method which allowed them to make the correctors CHEAPLY. Criterion knew that to compete they needed a cheap method as well hence the reason why they tried to copy Celestron's method but do it in a way to get around the patents. Meade is always trying  to do the same ie make it as cheaply as possible ie plastic gears , assembled in China etc. On  a side note this is why both Celestron and Meade came out with their new Coma free designs. They are better because they have less coma then a standard SCT but the driving force is that they use all spherical optics so they are cheaper to make, hence MORE profits. So I'm sure that if Meade and Celestron were trading knowledge that the Master block method was one of them since it cuts cost.

 

               - Dave 


Edited by DAVIDG, 17 February 2020 - 11:52 AM.

 

#63 markb

markb

    Viking 1

  • *****
  • Posts: 500
  • Joined: 16 Jun 2006
  • Loc: Long Island; in transition to Arizona

Posted 17 February 2020 - 12:24 PM

Congratulations on recognition of your solar panel material! Recognition is often lacking across our work careers.

 

I assumed Meade continued the vacuum pan method after the Celestron patent expired due to the expense of retooling. I doubt later collusion was necessary as the master bock method was well known and, I assume, well covered in the course of the Criterion suit. And any company can choose to share info, either for free or by licensing new technology, for the most part.

 

Very interesting comment on the coma free designs. I had assumed the change was done to just offer an improved scope over the competition's offering to increase sales, and had not thought it would also reduce costs. Particularly with Celestron, at least, making badly overdue changes to the mechanical design to allow the optical changes to work right.

 

The 'make more money' view also tied three events in my mind; Criterion gets sued and is mostly losing and incurring large legal bills, Halley's Comet is driving scope sales way up, and B&L buys Criterion's tooling (c. 1983-1984) to jump in with a ready to sell (but now know to be largely defective, and below B&L's rep) product. Pump them out asap, with existing tooling. The precipitous drop in post-Halley sales means, I would assume, no money and no fixes except for any already undertaken when it was thought the boom might continue. It would be interesting to here an insider view on what, if anything, was done on the manufacturing process front, if anything other than cosmetics, for the 8001 and Pro units.

 

Terra, I like those big aperture scopes but I think my back will only safely handle the GPS11 mount/dismount for another 5 years or so. Every time I hump it around it is indeed nerve wracking, both as to scope desrtuction and to body injury.


Edited by markb, 17 February 2020 - 12:37 PM.

 

#64 G-Tower

G-Tower

    Mariner 2

  • -----
  • Posts: 295
  • Joined: 24 Mar 2018

Posted 17 February 2020 - 12:47 PM

 I think the OP question has been answered and its also gone off topic to corrector making of which there's already an ongoing three year old topic on it. 


 

#65 Wisconsin Steve

Wisconsin Steve

    Aurora

  • *****
  • Moderators
  • Posts: 4,627
  • Joined: 30 Apr 2008
  • Loc: Wisconsin

Posted 17 February 2020 - 12:59 PM

 I think the OP question has been answered and its also gone off topic to corrector making of which there's already an ongoing three year old topic on it. 

Agreed. Let's get back on the original topic or start a new thread (or restart an old applicable one).

 

Steve


 


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics