58 replies to this topic

[schiefspiegler]

The sheer beauty of Unitron refractors -- their hallmark black and white paint scheme, the elegant "Uniclamps" for adding piggyback scopes and sliding tube counterweights, the polished metal knobs -- made the 5- and 6-inch Unitron refractors the stuff of boyhood dreams for geezers like me. Alas, as my late father lamented, "Son, why couldn't we have been born rich instead of good looking?" Compensating for inflation, the 6-inch Unitron fetched almost $70,000 in 2024 dollars.

 

In the words of the Irish Tourism Development Authority "There's a great future in nostalgia." I've attempted to recreate the aesthetic appeal of those classic instruments in a modest, far more affordable way.  Adorning the living room of my Florida house is a much-modified Bresser 6" f/8 achromat with piggybacked 80mm f/8 and 70mm f/10 achromats. Granted, it's not a towering f/16 behemoth like the original that inspired it, but it never fails to draw a crowd at star parties.

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Edited by schiefspiegler, 25 August 2024 - 05:19 PM.

[scout]

Wow, that's awesome. I've long-thought about adding Unitron-like rings and such to my modern 102mm refractor to give it a classic look.

[Opticsjunkie]

Awesome job on recreating that Unitron-feel! At first, I thought I was looking at the real thing, then I read your post !

[jsiska]

It looks good but how well does that mount handle the load?

[rob1986]

I really want to know!!!!

Thats an svp with a narrow to wide saddle adaptor and a pier.

[rob1986]

How much payload?

[manusfisch]

that's a whole lot of unitron going on their, nice setup and work.  Thanks

[schiefspiegler]

How much payload?

The OTA with rings and 8X50mm finder weigh in at just over 24 lbs (11 kg). I reckon that the combined 80mm f/8 and 70mm f/10 OTAs add another 6 to 7 pounds.

Edited by schiefspiegler, 25 August 2024 - 06:18 PM.

[jgraham]

Looks fantastic! You definitely captured the classic Unitron vibe. The only giveaway is the main telescope is so short! 😀

Nicely done!

[schiefspiegler]

I really want to know!!!!

Thats an svp with a narrow to wide saddle adaptor and a pier.

Well spotted! The mount is an Orion Skyview Pro with a half-pier. The 16-inch long half pier allows the tripod legs to be fully retracted, a big improvement. Without it the tripod would quiver like a reed.  It's surprisingly stable, in part because of perfect balance. An old rack & pinion focuser would no doubt have presented difficulties, but when the fine focus knob of the dual-speed focuser is adjusted there's nary a quiver at 200X due to its lack of breakaway torque and smoothness.

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Edited by schiefspiegler, 25 August 2024 - 08:02 PM.

[Rick-T137]

The sheer beauty of Unitron refractors -- their hallmark black and white paint scheme, the elegant "Uniclamps" for adding piggyback scopes and sliding tube counterweights, the polished metal knobs -- made the 5- and 6-inch Unitron refractors the stuff of boyhood dreams for geezers like me. Alas, as my late father lamented, "Son, why couldn't we have been born rich instead of good looking?" Compensating for inflation, the 6-inch Unitron fetched almost $70,000 in 2024 dollars.

 

In the words of the Irish Tourism Development Authority "There's a great future in nostalgia." I've attempted to recreate the aesthetic appeal of those classic instruments in a modest, far more affordable way.  Adorning the living room of my Florida house is a much-modified Bresser 6" f/8 achromat with piggybacked 80mm f/8 and 70mm f/10 achromats. Granted, it's not a towering f/16 behemoth like the original that inspired it, but it never fails to draw a crowd at star parties.

That looks stunning! What a fantastic setup!

 

Clear skies!

 

Rick

[rob1986]

The OTA with rings and 8X50mm finder weigh in at just over 24 lbs (11 kg). I reckon that the 80mm f/8 and 70mm f/10 OTAs add another 6 to 7 pounds.

About as much as an orion 10" F4.7 newt 27lb bare OTA

Good to know. This means with a wide saddle an f6 newt at 22lb should be no problemo.

I guess Orion wasnt completely insane when they advertised an SVP 10 in the very earliest days of the SkyView Pro

Edited by rob1986, 25 August 2024 - 06:18 PM.

[CHASLX200]

Don't see how that mount can hold all of that.

[Rick-T137]

Don't see how that mount can hold all of that.

Yeah, it looks like me at an all-you-can-eat buffet!

 

Rick

[CHASLX200]

My GP is shake city kitty with a 120mm Fract on it.

[schiefspiegler]

Don't see how that mount can hold all of that.

Your requirements in a mount seem to be quite extreme. In a recent post in this forum you described the Vixen Great Polaris mount as "maxed out" with a Celestron-Vixen C-102 4-inch f/9.8 achromat OTA that weighs less than 10 pounds and opined that the Great Polaris was "way too small" for an 11-pound Meade AR-5 5-inch f/9.8 OTA and recommended a G-11. This surely flies in the face of conventional wisdom.  

 

https://www.cloudyni...ries-refractor/

[schiefspiegler]

About as much as an orion 10" F4.7 newt 27lb bare OTA

Good to know. This means with a wide saddle an f6 newt at 22lb should be no problemo.

I guess Orion wasnt completely insane when they advertised an SVP 10 in the very earliest days of the SkyView Pro

There's more than the mass of the OTA to consider. The 12-inch tube diameter of those 10" Newtonians placed the OTA's center of mass at a considerably greater distance outboard and resulted in a much more cantilevered load than the 160mm diameter tube of the 6" refractor's OTA. I never regarded the Skyview Pro as up to the task of carrying a 10" f/4.7 Newtonian.

Edited by schiefspiegler, 25 August 2024 - 07:26 PM.

[CHASLX200]

Your requirements in a mount seem to be quite extreme. In a recent post in this forum you described the Vixen Great Polaris mount as "maxed out" with a Celestron-Vixen C-102 4-inch f/9.8 achromat OTA that weighs less than 10 pounds and opined that the Great Polaris was "way too small" for an 11-pound Meade AR-5 5-inch f/9.8 OTA and recommended a G-11. This surely flies in the face of conventional wisdom.  

 

https://www.cloudyni...ries-refractor/

You live close by so see for yourself.  No way that could be steady with all that stuff on that mount.  I am very picky about a steady mount and when using 350x+ jitters are a prob.

Edited by CHASLX200, 25 August 2024 - 07:08 PM.

[schiefspiegler]

You live close by so see for yourself.  No way that could be steady with all that stuff on that mount.  I very picky about a steady mount and when using 350x+ jitters are a prob.

Perhaps I'm just a pathological liar. But I have no doubt that there are many thousands of very satisfied owners of 102mm f/9.8 refractors carried by Great Polaris mounts and that very few find the combination "maxed out" unless they're taking long-exposure photographs in a gusty wind.

[Tenacious]

There's more than the mass of the OTA to consider. The 12-inch tube diameter of those 10" Newtonians placed the OTA's center of mass at a considerably greater distance outboard and resulted in a much more cantilevered load than the 160mm diameter tube of the 6" refractor's OTA. I never regarded the SVP as up to the task of carrying a 10" f/4.7 Newtonian.

+1.  Short accessory scopes balanced near the saddle should not impair stability much.  Newtonian mass is concentrated at the ends of the tube - different animal.

 

Good looking scope, schiefspiegler!

[Tenacious]

Did you make the mounting rings and brackets for the accessories?  They look great!

Edited by Tenacious, 25 August 2024 - 07:34 PM.

[schiefspiegler]

Did you make the mounting rings and brackets for the accessories?  They look great!

The mounting rings and nylon-tipped thumbscrews were purchased on Ali Express. 

 

https://www.aliexpre...ayAdapt=glo2usa

 

Knurled thumb nuts to lock the thumbscrews were also purchased on Ali Express:

 

https://www.aliexpre...ayAdapt=glo2usa

 

The rings are attached to these narrow, lightweight dovetail rails:

 

https://www.aliexpre...ayAdapt=glo2usa

 

The trapezoidal connectors joining between the flats of the OTA rings and the dovetail rails were 3-D printed. 

Edited by schiefspiegler, 25 August 2024 - 07:51 PM.

[schiefspiegler]

+1.  Short accessory scopes balanced near the saddle should not impair stability much.  Newtonian mass is concentrated at the ends of the tube - different animal.

 

Good looking scope, schiefspiegler!

Thanks. You're a mechanically literate voice of reason. Decades ago I replaced the aluminum tube of a 4-inch f/12 refractor with decorative polished brass tubing of greater wall thickness. The resulting OTA was far more massive but actually proved to be just as stable because the mass was more uniformly distributed rather than concentrated at the ends.

Edited by schiefspiegler, 25 August 2024 - 07:59 PM.

[RalphMeisterTigerMan]

Please forgive me if the following is considered "blasphemy". Has anyone ever replaced the achro lens of a vintage Unitron with a modern Apo lens and have the best of both worlds? Just thinking. Plus, you would save the money on a new Moonraker. Unless you really love chrome.

 

Clear skies and keep looking up!

RalphMeisterTigerMan

[deSitter]

2017 eclipse - Meade 127ED and ETX90.

 

-drl

 

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