Yolo on ebay

[SilverAstro]

It's a very long time since I saw anything about unobstucted Yolos - maybe cos of the cost !!

http://www.ebay.co.uk/itm/Yolo-Off-axis-unobstructed-folded-reflector-8-F12-apo-refractor-/322382332697?hash=item4b0f7c0319:g:Vy0AAOSwUKxYcBuQ

deffo one for the diy with time to spare !

EDIT : Hmmm, it isnt a Yolo is it ? It has a lens on the front !

[Davey-T]

Isn't it what's called a Dialyte or Zerochromat design ?

Is it a reflector or refractor ? can't make it's mind up in the title 

Dave

[John]

Maybe it's a hybrid design ?

Very unusual though. I'd love to look through it but maybe not to own it

[SilverAstro]

So long ago ! there were Yolos and Schiefspieglers (sp) and Schupmanns and wierdo designs of allsorts, I'm just trawling through the Stellafane site now trying to remember !

[SilverAstro]

A true Yolo I think was a folded two (or three ?) mirror Z shaped deesign

this quote may be someting like the ebay  one

"Unlike a catadioptric such as a Schmidt Cassegrain, the Schupmann uses refractive components for primary imaging, and reflective mirrors as relay elements. "

dunno, still digging

[ecuador]

Quote

Comprises 8" aspheric front lens, hyperbolic secondary mirror , third elipsiodal mirror to give 8" refractor type views in folded scope only 1.3m long weighing 8kg.

How would it give "refractor type views" with 2 mirrors? Unless he means that the front lens adds CA ?

Sorry for the ignorance, but it is a £4200 buy it now, so I am wondering if it is worth that much...

[SilverAstro]

"refractor type" being shorthand for unobstruced with mirrors ie. without the usual mirror support spiders and things

 

[Davey-T]

8" Zerochromat design is probably  £10.000 so if it's something similar who knows ?

Dave

[John]

I think the term "refractor like" probably refers to well defined airey disks and diffraction rings and no diffraction spikes or other effects that you get in an obstructed system.

My Intes 6" mak-newtonian gave "refractor like" views

 

[barkis]

After a look I thought it might be a Coude / Nasmyth
but clearly not.

 

 

 

 

[Nyctimene]

On 14.1.2017 at 00:10, SilverAstro said:

A true Yolo I think was a folded two (or three ?) mirror Z shaped deesign

this quote may be someting like the ebay  one

"Unlike a catadioptric such as a Schmidt Cassegrain, the Schupmann uses refractive components for primary imaging, and reflective mirrors as relay elements. "

dunno, still digging

Silver Astro,

I don't think it's a Schupmann Medial. The Medial, following Riekher (Rolf Riekher: "Fernrohre und ihre Meister"; VEB Verlag Berlin 1957) was designed as a refractor with a single front lens (no achromat!), and a compensation system of a small mirror with a lens system (therefore "Medial"-between lens and mirror). A small 90° prism in the refractor's focus directed the light to the compensation system (which, with a diameter of 20% of the objective's diameter, could be built much cheaper than an achromatic objective). Nowadays, we would speak of this system as a catadioptric design.

The Medial never was a folded design, and it's tube must have had the full focal length of the front lens (as the drawings in Riekher show).

I cannot guess which optical design the "Yolo" on ebay has; never seen such a construction.

Stephan

 

[SilverAstro]

21 minutes ago, Nyctimene said:

I don't think it's a Schupmann Medial.

The Medial never was a folded design, and it's tube must have had the full focal length of the front lens (as the drawings in Riekher show).

I cannot guess which optical design the "Yolo" on ebay has; never seen such a construction.

Thanks N.

No me neither now

Some people did fold it ! ( whether  or not they were right to do so is another matter ) http://www.willbell.com/tm/schupmann.htm and https://www.wa2guf.org/building-a-schupmann/  just two at random.

No, I cant find anything to suggest the parentage of the ebay thing, and at that price I have stopped searching (would have been interesting for the owner to point us somewhere though )

No worries it was a good excuse to do a cloudy nights prowl round the Stellafane archives ( but seems the art of odd telescope building may be passing, so many dead links round the Stevick-Paul etc. sites )

 

[Nyctimene]

Silver Astro,

thank you for information about those modern variants of the Medial; I've never heard of that before and always thought of the Medials as of some kind of long-gone optical dinosaurs. Very interesting renaissance. But is it worth the effort to build such a complex system?

Stephan

[SilverAstro]

2 minutes ago, Nyctimene said:

 But is it worth the effort to build such a complex system?

Indeed, I have thought the same ! ( and certainly not at that price !!)

But in days of yore the grinders were perhaps more interested in the journey ? The advent of affordable commercial 'scopes puts a different light on diy now, my first 6" used mirrors ground by an english gent and built into a scope by me cos I could not afford to buy one.  Now I am going to order a bog standard something ( but maybe fiddle with penguin guts just for fun )

I dont suppose there is an English/American translation of your Riekher ref. on the web anywhere ?

[Nyctimene]

6 minutes ago, SilverAstro said:

Indeed, I have thought the same ! ( and certainly not at that price !!)

But in days of yore the grinders were perhaps more interested in the journey ? The advent of affordable commercial 'scopes puts a different light on diy now, my first 6" used mirrors ground by an english gent and built into a scope by me cos I could not afford to buy one.  Now I am going to order a bog standard something ( but maybe fiddle with penguin guts just for fun )

I dont suppose there is an English/American translation of your Riekher ref. on the web anywhere ?

There was a German reprint a few years ago; never heard of a translation; must do some investigation on the web.

Stephan

[Putaendo Patrick]

I see the price has dropped considerably - with bidding opening at 1,600 or buy-it-now at 2,500 pounds. As others have said, I'd love to have a look through it, and know who the "UK master optician" was who made it. Superficially at least, it looks nicely constructed.

The Yolo design was originally built by Arthur S. Leonard in California in the early 1960s. He published a rather ephemeral booklet describing it in about 1964/5:

Leonard also published later articles on the Yolo in amateur astronomy magazines and optics journals. Jose Sasian has also published an article on his modified Yolo. Leonard also designed the Solano version, both named after counties near to San Francisco.

Arthur S. Leonard was a very well respected amateur astronomer and telescope maker - even so, unfortunately I've come across very little concrete biographical information on him. Leonard joined the Eastbay Astronomical Society in 1927, three years after the group was founded and remained an active member for many years, being vice-president and president on occasions. He was also a leading member of the Sacramento Valley Astronomical Society.

Leonard was also a respected participant in the Moonwatch program established to monitor satellite activity in International Geophysical Year 1957-1958 and was on the national advisory committee.

He was awarded the G. Bruce Blair Medal in 1962 by the Western Amateur Astronomers.

Leonard studied Bachelors and Masters degrees in science at the University of California at Berkley. He apparently worked for several  aerospace companies and the Jet Propulsion Laboratory before obtaining an academic position as Lecturer in Mechanical Engineering (perhaps agricultural engineering?) at the University of California's central California campus.

Arthur (Art) S. Leonard died on October 13, 2001.

Richard Buchroeder and Arthur Leonard in front of an Orange County Astronomers display at the 1971 Riverside Telescope Makers Conference.

 

[Peter Drew]

I've had limited experience with TCT's (Tilted Component Telescopes). My overall view is that the optical/mechanical complexity for marginal improvement over other high end telescopes of more conventional design means that they are unlikely to become mainstream commercial equipment. They offer interesting challenges to advanced amateur telescope makers and there is a small niche market for the rare professional custom built versions, the Zerochromat falls into this category. I've made several folded refractors, 6" and 8" aperture and F20-F25 to give minimum CA at a reasonable mechanical length which have tilted mirror components but they are still quite heavy and bulky, a 8" is similar to a 10" F5 Newtonian tube. Regardless of their attributes, you are not going to see a TCT at every star party.   

[SilverAstro]

9 hours ago, Putaendo Patrick said:

The Yolo design was originally

Yes, and featured frequently in the SA columns of Ingals et.al., at Springfield and in Berry's magazine etc. but as your diagram shows it did not (usually?) have a lens at the front, so I was enquiring for refs. to this particular design. I didnt get as far as checking out if its intermediate mirrors figures conformed to Yolo either, I gave up at that stage Especially as I have mislaid my ATM folders seemed quicker to ask here than delve in the attic

,, "the "UK master optician" was who made it",,,, > and one might have hoped that he and its current owner might be punters of this parish and could put us out of our puzzlement ! but seems it is not to be !!

[Putaendo Patrick]

While it's impossible to know exactly what is going on in the box without physically examining the e-bay telescope, it looks like a variation which Allan Mackintosh and Arthur Leonard refer to as the Hamiltonian-Yolo. See volume one of Mackintosh's Advanced Telescope Making Techniques, especially the essay in chapter three New Horizons for Tilted-Component Telescopes by Leonard.

Sorry about the poor scan, but you should be able to see the idea. The original Hamiltonian telescope was patented by W. F. Hamilton in 1814.

[SilverAstro]

14 minutes ago, Putaendo Patrick said:

refer to as the Hamiltonian-Yolo.

Sorry about the poor scan, but you should be able to see the idea.

No problem, yes indeed I can. Thank you for that, most interesting. deffo a contender

I had previously looked at the Hamiltonian, for example partway down this page  http://www.telescope-optics.net/catadioptric_telescopes.htm but didnt understand it and most other Hamiltonians looked more like the usual cassegrain perforated types.

Thanks, a new direction to read up on ! >>

 

[SilverAstro]

2 hours ago, Putaendo Patrick said:

See volume one of Mackintosh's Advanced Telescope Making Techniques, 

Ah, I dont have that one,

The good news is that it is available to download , the bad news is that one has to join dubious sites to do so ! so I may wait till next Xmas