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Bird Jones Telescope "Years Available" Question

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#1 JJDreese

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Posted 03 July 2024 - 10:29 PM

I have a "years available" question as in, "When in history could a normal person have bought these?"

 

There were only four five true commercially available Bird Jones telescopes that were sold.  I'm trying to zero in on when their heyday was.  Why?  Because I believe it puts a transition time between when parabolic mirrors were prohibitively expensive and when they were too cheap to ignore.

 

Question: Do you know the approximate years that each of these were available?

 

Tasco/Vixen 8V  (red tube)

 

Tasco/Mizar 16T  (white tube)

 

Celestron (Cometron) Comet Catcher Jr.  (gray tube)

 

Celestron G8-N  (black tube)  8"

 

Celestron C150-HD (black tube)  6"


Edited by JJDreese, 04 July 2024 - 04:47 PM.


#2 RalphMeisterTigerMan

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Posted 04 July 2024 - 12:26 AM

I cannot really answer your original question. If there ever was a "hay day" for these scopes, I do not remember it.

 

I personally believe that the Jones Bird scope was one those, "well, it really looked great on paper" but no one could ever make the design work. Either you have a short focal length reflector to which you can use a normal barlow, or you make a long focal length reflector. Sorry, but I have never seen a JB scope that actually worked. Who in the right mind would put a barlow "ahead" of the secondary.

 

I actually was given one and try as I might, I just could not make it work, and I tried. Sorry to say but I ended up putting it into the recycling bin.

 

Clear skies and keep looking up!

RalphMeisterTigerMan


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#3 rob1986

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Posted 04 July 2024 - 01:12 AM

They say that the vixen version and the mizar versions were actually pretty good.
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#4 DrBB

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Posted 04 July 2024 - 08:02 AM

Just dropping in to briefly share my own totally off-topic expertise as a former professor of Middle English: "heyday" is correct, one of those archaisms that pretty much mean what they sound like, and to me a delightful survivor from Early Modern English (roughly the time of Shakespeare). Now don't get me started on what "playing fast and loose" really means.... cool.gif

 

Carry on.


Edited by DrBB, 04 July 2024 - 08:02 AM.

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#5 rutherfordt

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Posted 04 July 2024 - 09:32 AM

I have a "years available" question as in, "When in history could a normal person have bought these?"

 

There were only four true commercially available Bird Jones telescopes that were sold.  I'm trying to zero in on when their heyday was.  Why?  Because I believe it puts a transition time between when parabolic mirrors were prohibitively expensive and when they were too cheap to ignore.

 

Question: Do you know the approximate years that each of these were available?

Although I don't know when the first commercial versions of this design became available, the first mention of it was in the "Gleanings for ATM's" column" in the September, 1957 issue of Sky & Telescope.  The title of the article was "A Wide-Field Telescope with Spherical Optics."  The author of the article was Robert T. Jones.

 

From reading the article, it does appear that it took a couple of iterations before Mr. Jones came up with a version that performed the way he envisioned it.  It also does appear, as you surmised, that it was a design that could be easily constructed by an amateur using spherical optics instead of the much more difficult to make parabolic ones.

 

No mention of anyone named "Bird" in the article, so I have no idea when he came into the picture or what he did.

 

Tom


Edited by rutherfordt, 04 July 2024 - 10:31 AM.

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#6 JJDreese

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Posted 04 July 2024 - 04:29 PM

Thanks for all the replies!  As for years available, I suspect it was from early 1980's until early 1990's.  If I could find a user manual for any of the above four telescopes, that would help.

 

I have that same 1957 article  by RT Jones and one by Bird/Bowen from the late 1970's.  RT Jones came up with the idea for putting the corrector lens before the secondary, so he had the 95% solution years before Bird & Bowen tweaked the corrector in about 1976.  As to why it's not called the Bird-Bowen-Jones telescope, I have not found an answer other than Mr. Bowen (a professional optics guy) wanted to keep his hobby separate from his profession?

 

John



#7 ericb760

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Posted 04 July 2024 - 11:25 PM

Dave Trott seemed pretty impressed with the Mizar CX-150.
https://www.youtube....Rwm-sE5s&t=240s


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#8 EJN

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Posted 04 July 2024 - 11:40 PM

https://www.cloudyni...s-history-info/

 

https://www.cloudyni...d-bird-joneses/

 

Telescope Making #3 Spring 1979:

 

post-12877-0-28806300-1642558935.jpg

 

post-12877-0-91013200-1642558957.jpg


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#9 deSitter

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Posted 07 July 2024 - 08:32 PM

I cannot really answer your original question. If there ever was a "hay day" for these scopes, I do not remember it.

 

I personally believe that the Jones Bird scope was one those, "well, it really looked great on paper" but no one could ever make the design work. Either you have a short focal length reflector to which you can use a normal barlow, or you make a long focal length reflector. Sorry, but I have never seen a JB scope that actually worked. Who in the right mind would put a barlow "ahead" of the secondary.

 

I actually was given one and try as I might, I just could not make it work, and I tried. Sorry to say but I ended up putting it into the recycling bin.

 

Clear skies and keep looking up!

RalphMeisterTigerMan

The Jones-Bird is a real catadioptric telescope with very big advantages and few disadvantages. The cheap fast Newtonian reflector with a Barlow stuffed into the focuser is just that - it's not a Jones-Bird telescope. That's like calling a mule a mustang because you bought it from your Boss.

 

In all cases I know of, the J-B has a wide-spaced 2-element corrector IN FRONT of the secondary, not behind it. Like all catadioptrics with small correctors, it is extremely sensitive to proper collimation.

 

-drl


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#10 tim53

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Posted 07 July 2024 - 11:28 PM

The Jones-Bird is a real catadioptric telescope with very big advantages and few disadvantages. The cheap fast Newtonian reflector with a Barlow stuffed into the focuser is just that - it's not a Jones-Bird telescope. That's like calling a mule a mustang because you bought it from your Boss.

 

In all cases I know of, the J-B has a wide-spaced 2-element corrector IN FRONT of the secondary, not behind it. Like all catadioptrics with small correctors, it is extremely sensitive to proper collimation.

 

-drl

if the cheaper J-Bs with the corrector in the focuser really only used a barlow, the images would be a lot worse than they are, due to barlowing the spherical abberation of the fast spherical primary,  i have one of the meade versions,  if i collimate it carefully after approaching focus from one direction, the images are pretty tight. .but as soon as i change focus on the plastic focuser, it goes out of collimation. Someday i'll machine a focuser where the corrector is fixed in the base and doesn't move with the draw tube,


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#11 deSitter

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Posted 08 July 2024 - 06:17 AM

if the cheaper J-Bs with the corrector in the focuser really only used a barlow, the images would be a lot worse than they are, due to barlowing the spherical abberation of the fast spherical primary,  i have one of the meade versions,  if i collimate it carefully after approaching focus from one direction, the images are pretty tight. .but as soon as i change focus on the plastic focuser, it goes out of collimation. Someday i'll machine a focuser where the corrector is fixed in the base and doesn't move with the draw tube,

Cool, which model? EJN's posted article shows 3 types of corrector, one of which is just a cemented doublet.

 

Unlike a Mak where you are really constrained by the size and weight of the meniscus, a large but manageable J-B is completely doable, and all spherical so you don't need to be Alvan Clark to make one. Easy to mass produce as well.

 

-drl


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#12 rutherfordt

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Posted 08 July 2024 - 07:26 AM

Here is the illustration from the original article, showing the arrangement of the auxillary lenses, which were placed before the secondary (not after, as with a typical Barlow).

 

Jones Telescope.JPG


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#13 deSitter

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Posted 08 July 2024 - 08:14 AM

if the cheaper J-Bs with the corrector in the focuser really only used a barlow, the images would be a lot worse than they are, due to barlowing the spherical abberation of the fast spherical primary,  i have one of the meade versions,  if i collimate it carefully after approaching focus from one direction, the images are pretty tight. .but as soon as i change focus on the plastic focuser, it goes out of collimation. Someday i'll machine a focuser where the corrector is fixed in the base and doesn't move with the draw tube,

Thinking about this and reading TO - it is not inconceivable that a combination of fast sphere plus off the shelf achromat would reduce SA on axis. But if that is so, then using a barlow with a well-corrected paraboloid should do the opposite, and add SA that wasn't there before.

 

-drl


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#14 Jon Isaacs

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Posted 08 July 2024 - 09:09 AM

When discussing Jones-Bird scopes, the Opticons made by Rik ter Horst have to be at the top of the list.

 

https://www.cloudyni...oval/?p=8420475

 

This 12 inch F/6 Jones-Bird reputedly blows away C-14s in sharpness and contrast.

 

Jon


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#15 topomountain

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Posted 08 July 2024 - 09:40 AM

Just dropping in to briefly share my own totally off-topic expertise as a former professor of Middle English: "heyday" is correct, one of those archaisms that pretty much mean what they sound like, and to me a delightful survivor from Early Modern English (roughly the time of Shakespeare). Now don't get me started on what "playing fast and loose" really means.... cool.gif

 

Carry on.

ill bite

 

enlighten me on the term "fast and loose" please sir

 

john


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#16 jgraham

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Posted 08 July 2024 - 10:35 AM

I knew that the original Jones design placed the corrector before the secondary. I always wondered if the Jones-Bird variant moved it to after the secondary and into the draw tube.


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#17 JJDreese

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Posted 12 July 2024 - 02:18 PM

R.T. Jones' design put the corrector lens between the primary and secondary.  The Bird-Jones (really it should be called the Bird-Bowen-Jones) tweaked the corrector lens, but kept it between the two mirrors.

 

 

I knew that the original Jones design placed the corrector before the secondary. I always wondered if the Jones-Bird variant moved it to after the secondary and into the draw tube.


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