Carl Anderson's Telescope Web Site
Promoting unobstructed reflecting telescopes of all types:
Yolo, Schiefspiegler, TCT's, Catadiaoptric, the quest continues....
e-mail Carl Anderson
Yolo mirror sets for sale
New improvements of my Excel workbook "Unobstructed Design":
Now compatible  with European users who use a comma as the decimal point.  This makes designing an unobstructed scope easy!  There are spreadsheets for two types of Yolos, three types of Schiefspieglers and the Stevick-Paul design.  Parameters are entered into the green cells, formula results are displayed in the blue cells.  A click of a button will create a text file,  ready to load into the program WinSpot for displaying the layout and spot diagram.
Click here to download.

Step by step instructions.
Art Leonard (inventor of the Yolo) with what appears to be his 6 inch F18.8 Yolo reflector.  This may have been at the Riverside meeting in 1979.  Both mirrors of this telescope were polished spherical with a warping harness on the 4.25 inch secondary mirror to elliminate astigmatism.  "Final figuring" was then done by adjusting the tension while viewing a star at high magnification.
(Photo provided by Jack Borde)
New on the web!
The Swiss Yolo Group now has a new website.  There are photos and technical information on many Yolo telescopes built by its members.  The largest of which is a 25cm (10 inch) F8.3 Yolo.  Its aplanatic design features an aberration free wide field view.
The Largest unobstructed reflecting telescope!
Chris Krauskopf of Louisville, Kentucky, built this very large Yolo telescope, featured in Sky & Telescope Feb 2008  page 84.. 

It features:
*  18 inch aperture
*  polished in toroid figure
*  focal ratio F15
*  full thickness mirror blanks
*  special high efficiency mirror coatings
*  tranportable

For more about this incredible telescope
click here.
Bobby J. Schiffman of the Amarillo Astronomy Club writes about the YOMAX telescope at the RMSS 2007 click here.
Two Yolo telescopes in the Netherlands!

Jo Dahlmans and Kai Ries, both from Limburg, Holland crafted these fine Yolo unobstructed telescopes.  One has a bent secondary, the other a polished in toroid figure.
For more info click here.
The 2nd largest Yolo telescope in America
Carl's 8 inch Yolo telescope as seen in Sky and Telescope , January 2006 issue.
Frequently Asked Questions: click here
Carl's Glass Bender Telescope
Also new on the web:
Bela with his toroid secondary mirror, for his soon to be completed 25 cm Yolo.
Bela with his 23 cm Yolo. 16 cm Yolo.
Bela has just finished building a 250 mm (10 inch) Yolo telescope.  This is one of his first photos taken with his Yolo.
Berente Bela   sent these photos and information about his web site.
(in Hungarian, the last name is written first)
Bela has made three Yolos (16, 21 and 23 cms in diameters). All have secondary mirrors with polished in toroid figures!
See:
Bela's Web Site        also    Belas new web site
You can also see his pictures of the Moon, Venus, Mars, Jupiter, Saturn and double stars at "mely-eg, kettosok" at
this web site.
Choose Fotoalbum.  Then choose kategoria (category) , eszlelo (observer) then push "mehet" (go).

To translate some of his web pages, go to:
Free Online Translator
Copy and paste in some text to translate and then select Hungarian (CP1250) to English or other language, click Translate.
Carl's Curiosities:
Can a Yolo telescope have more than two mirrors?
The Shafer Telescope:
The Shackman telescope:
Leonard's 3-Dimensional Yolo
Take a trip down memory lane with The New FI-NIS Off-Axis Catadiaoptric Telescope:
Reproduced with permission of Sky Publishing Corp.
The Lohmann telescope:
Further development on the two mirror unobstructed design:
See patent 1578899
(Google patents)
The Schupmann Telescope
The Brachy Telescope, developed by Vienna opticians J. Forster and Karl Fritsch in 1877, was the forerunner of what we now call a Schiefspiegler.  (The word Brachy is from the Greek brachys meaning short)
Link provided by Wolfgang Birkfellner.
Schiefspiegler Design:
Anton Kutter's booklet "The Schiefspiegler (Oblique Telescope)"  can now be viewed on the web.
An inside look of his observatory.
An outside look of his observatory.
Some Schiefspiegler history.
Yolo Design:
Arthur Leonards Yolo Booklet
.  
A must read for anyone considering a Yolo telescope.

Carl's Simple Yolo Design.

Stevick-Paul Design:
David Stevick's
Stevick-Paul Telescope
The
Stevick-Paul Telescope History
The
Stevick-Paul Telescope Design Manual
8" Stevick-Paul telescope optics evaluation by Don Good
TILTED COMPONENT TELESCOPES PART I       by Dick Suiter

TILTED COMPONENT TELESCOPES PART II      by Dick Suiter
Dave Stevick has just enhanced his spot plotter program called WinSpot.  One of the new features allows you to scale up or down an existing design with the click of a mouse.
The new version can be downloaded
here.
Software:
David Stevick's program
WinSpot.  Use this to design unobstructed telescopes.
Jose Sasian's
TCT.   Use this to design unobstructed telescopes.
Aberrator.   This program makes diffraction plot of star images.

Raytracing and analysis program:  OSLO EDU from
Sinclair Optics.
Step by step how to learn Oslo by Steve Fejes.  (click on folders and html pages)
Carl's Yolo and Schief Spreadsheet:
New:  Unobstructed_Design Excel spreadsheet can calculate the parameters needed to design a Yolo, Schief, or Stevick-Paul telescope.  The spreadsheet can automatically create a file to be opened with Dave Stevick's program WinSpot .  Then plot the scope layout and spot diagrams.
Example walk through on how to design a 10 inch Yolo using the spreadsheet.
Step by step instructions.
Other Links:
Tim's Telescope.   This is where I got my inspiration for using fiberglass rods and glue!
Weird Telescopes.  Unobstructed telescopes of all types.
Dan Steiner's Yolo Telescope.
Yahoo Off-Axis Group.  Here is where a handfull of unobstructed enthusiasts post files, photos, e-mails, etc.
Off-Axis Binoculars!
200 mm kutter schiefspiegler built by Philip Doutrelignein of Belgium.
Ed Jones'  8 inch Herschelian
Ed Jones'  10 inch Herschelian window scope. (Observe inside, telescope is outside!)
Schiefspieglers
Lutz Liebers of Berlin, Germany built this 125mm anastigmatic Schiefspiegler.  Focal length 3500mm.  For more info click here.
Georg Dittie has finished the English translation of his website describing his Double Meniscus Schiefspiegler 250/5000.
He added the optical path and a table with the exact radii and tilt angles of the elements.  This design has much improved edge of field performance over other Schief designs.
The Minnesota Astronomical Society / Amateur Telescope Makers:
2003 MAS ATM gathering
2004 MAS ATM gathering 2005 MAS ATM gathering
Mirror testing at the MAS ATM gathering
Oct 24, 2006
ATM visit at Bill's workshop
April 5, 2006
ATM gathering
Jan 23, 2007
2006 MAS ATM gathering
ATM gathering
Feb 11, 2009
ATM gathering May 30, 2007
the club acquires the 18 inch Zygo laser interferometer!
Grinding and polishing tips for making Schiefspiegler mirrors
Making a lap with Acculap synthetic pitch
Polishing results with the Acculap pitch