21 replies to this topic

[JJDreese]

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.

[RalphMeisterTigerMan]

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

[rob1986]

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

[DrBB]

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.... 

 

Carry on.

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

[rutherfordt]

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.

[JJDreese]

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

[ericb760]

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

[EJN]

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

 

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

 

Telescope Making #3 Spring 1979:

 

 

[deSitter]

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

[tim53]

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,

[deSitter]

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

[rutherfordt]

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).

 

[deSitter]

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

[Jon Isaacs]

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

[topomountain]

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.... 

 

Carry on.

ill bite

 

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

 

john

[jgraham]

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.

[JJDreese]

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.

[Dave Roscoe]

I bought a Skywatcher 130mm "Catadioptric Newtonian" scope in the mid 90s from Sky Instruments, through a dealer in Ontario. This was the type that had the corrector mounted in a tube between the primary and secondary mirrors.  After owning it for about a year I thought the collimation seemed to have deteriorated because I could never achieve the kind of focus I remembered from when it was new. I asked some of my more experienced friends to help me collimate it but we only seemed to be able to make it worse. I contacted the dealer to ask if there was any info or instructions for collimating it and he curtly told me it had to be collimated "at the factory". I contacted Sky Instruments and actually talked to Glenn Speers himself. He started telling me I was going to have to remove the barlow from the focuser in order to collimate it. I explained that it wasn't like that and the corrector lens was mounted between the secondary and primary, and he said, "Oh, it's one of those!" He said they were nearly impossible to collimate and made me an offer to return the scope, along with $100, and he would ship me a new 6 inch Skywatcher Newtonian. I took him up on the offer and found the new scope a breeze to collimate and a great performer. I still have it.

 

Anyway, I just came across a well-made Youtube video about the history of the Bird-Jones design that I thought might be interesting:

https://www.youtube....h?v=PYgjP2kKcSA

[highfnum]

I got one of those Meade "bird" like Tim53 also

 

it  does the job  barely - I found it hard to collimate

 

I  rank  this scope less effective than the notorious DX8

 

I keep some bad scopes as examples

 

Tim53  what is your method to collimate ?

[highfnum]

great video so Meade is an FC type

[highfnum]

Ha went thru my old S&Ts

found I had  9/57 with RT Jones

article 

thx guys

 

 

 

[scout]

Anyway, I just came across a well-made Youtube video about the history of the Bird-Jones design that I thought might be interesting:

https://www.youtube....h?v=PYgjP2kKcSA

The video was made by the creator of this very topic you're replying to.

And welcome to Cloudy Nights.