13 replies to this topic

[starman876]

Found this list on Wikipedia

 

https://en.wikipedia...ting_telescopes

 

Just look how long some of these scopes were.  I find it amazing they would stay in alignment. 

[deSitter]

Found this list on Wikipedia

 

https://en.wikipedia...ting_telescopes

 

Just look how long some of these scopes were.  I find it amazing they would stay in alignment. 

Conrady criterion for achromats - f/ratio needed for a colorless view - is 5D with D in inches. 24", f/120! That's almost a football field. That's for an achromat! Imagine how extreme a single lens would need to be.

 

-drl

[Phil Perry]

Some of the very earliest attempts at telescopy didn't even bother with a tube, as it would have to be absurdly long. An assistant to the astronomer would hold (or more likely, adjust) the objective lens way up on a tower, while the astronomer stood on the ground (with the eyepiece)!

Edited by Phil Perry, 25 January 2025 - 08:32 AM.

[Jay_Reynolds_Freeman]

Found this list on Wikipedia

 

https://en.wikipedia...ting_telescopes

 

Just look how long some of these scopes were.  I find it amazing they would stay in alignment. 

I have worked as a volunteer at Lick Observatory, assisting guests and providing small-telescope views at summer public outreach sessions. In that context, I have observed through the 36-inch refractor many times. It is rock solid.

[jragsdale]

Wonder if I should add my 12" Clark to the list?

[RyanSem]

I saw the Alvin Clark at Lowell a few years back and it was a MONSTER. I can't imagine how the Yerkes can be nearly double the length and lens diameter. Definitely on my bucket list of places to visit.  

[jragsdale]

I saw the Alvin Clark at Lowell a few years back and it was a MONSTER. I can't imagine how the Yerkes can be nearly double the length and lens diameter. Definitely on my bucket list of places to visit.  

Yeah, the 12" f/15 "guidescope" looks diminutive next to the 24" f/16.

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[Serenity Now]

Darn...missed the list by an inch and a half with my D&G 8" f/12. Missed it by THAT much LOL!

[rev]

Moscow Observatory of Moscow State University, double refractor

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Edited by rev, 16 March 2025 - 09:54 AM.

[abe]

I was surprised how many large refractors, like stars, are doubles.  

1. Grand Lunette, Meudon, France

https://en.wikipedia...Great_Refractor
 

2. Großer Refraktor, Potsdam Germany
https://en.wikipedia...Great_Refractor
 

3. Bosscha Observatory, Bandung Dutch East Indies
https://en.wikipedia...cha_Observatory
 

4. Grubb Parsons Double Refractor, Saltsjöbaden, Sweden
https://www.gettyima...-photo/90769436
 

5. Radcliffe Double Refractor, Oxford UK
https://en.wikipedia...ffe_Observatory
 

6. Carnegie Double Astrograph, Lick Observatory, Mount Hamilton CA
https://www.lickobse...uble-astrograph
 

7. Fabra Observatory, Barcelona Spain
https://en.wikipedia...bra_Observatory
 

8. Leiden Photographic Refractor, Leiden, Netherlands
https://www.universi...ouble-refractor

 

9. Astrograph Vienna Observatory, Vienna Austria
https://astro.univie...thschild-coude/

 

10. Great Refractor Kuffner Observatory, Vienna Austria
https://en.wikipedia...ner_Observatory

I guess if you go through the trouble to build the mount and dome, it makes sense to stack up a few tubes (although for the Bossca Zeiss, they put two objectives in a single tube). 

Edited by abe, 16 March 2025 - 11:36 AM.

[Don W]

I have the good fortune to observe through the 40” at Yerkes twice. Jupiter and Saturn were quite amazing.

 

one of our Club members had a 4” Clark, another a 10”.

 

A local old timer had an observatory with 3 domes. The big one housed a 16” J.W. Fecker Cassegrain with a 5” Fecker refractor riding on top.

 

Second dome featured another 5” Fecker used solely as a solar scope projecting the suns image on preprinted solar maps. The sunspots were carefully penciled in. 
 

Dome number 3 was much smaller and held a sweet 3” Bardau refractor. When the other scopes were in use I liked to sneak off and have it all to myself.

[stomias]

I saw the Alvin Clark at Lowell a few years back and it was a MONSTER. I can't imagine how the Yerkes can be nearly double the length and lens diameter. Definitely on my bucket list of places to visit.  

It is incredible. The tube is only the beginning of its magnificence! The rising/lowering floor is something to behold.

Edited by stomias, 16 March 2025 - 02:37 PM.

[M66]

The nice thing about large refractors is they were well built!

 

If properly maintained they last a number of lifetimes, as long as the atmosphere doesn't eat at the lens too much.

[JonH]

I was surprised how many large refractors, like stars, are doubles.  

 

Thanks for that interesting list. The Štefánik observatory in Prague also has a nice double Zeiss (200 mm). There is a fascinating story of mechanical ingenuity behind the way a dedicated band of astronomers kept the massive Zeiss mount operational during the soviet era. Because of the shortage of spare parts, the original RA drive could not be replaced after burning out so a washing machine motor was adapted instead (this was related to me by a docent in 2019).