Astronomy Telescopes Optics Accessories

Telescope Mount Examples Equitorial or Dobsonian
Home
Telescope Mirror Cells
Mirror Cell Quote Page
Personal 32" Telescope
14 Foot Palomar type Dome
Grinding your Telescope Mirror
Telescope Cradles and Holders
Telescope Finders and Rings
Telescope Vane Spiders
Telescope Mount Types
CCD Image Science Method
Telescope Casting Parts
Joe's SNe Spectroscopy
Contact Us
Our Location is in the High Desert of California, USA

Here is a run down of telescopes built by old Joe.
 
MY first telescope attempt was 12.5"F10 pyrex mirror to be mounted in a full 'A'-Frame double yoke. I made the ultimate Radius = Focal Length error and it was not for several years before I reground the 12.5" back to f6 on a steel precurved tool.

More of my telescopes over the years. Here is a Monster all of pipe and fiberglass.  Light weight was not the order of the day. Portable and massive was the way to go in the 60's.

12.5" F6 with all the heavy trimings
12joemonster.jpg
Note Pully Drives, Rotatable Cradle, Giant eyepiece holder

Equatorial was the mode for many years. I tried fork mounts and side saddle mounts. Nothing is permanently finished.  I am still machining on the parts for my 12.5"f4 nova search scope. It will be done some day! before all the super-nova are found.

Thing 12.5" on Pipe Fork and Open Truss
12f6fork.jpg
Did this shake and shake.

Light weight RAIL telescope mount
railtele.jpg
Open air cooling on a steel RAIL

The development of telescopes range from the over weighted to the light weighted.  Inorder to test mirrors on a telescope i came up with the RAIL system. Pictured here are several of my 12.5" RAIL systems.
 
F4 nova search system with CCD.
 
and
 
F10 a planetary system with long focal lenght requiring a 6" folding flat to return the beam throught the middle of the primary mirror.
 
In some cases of a 10"F10 i used a 4" flat to return the beam
above the telescope primary.

Here are  some modification to your Dobsonian AZ-EL mount that will work cheaply to convert it from AZ-El to Equatorial.
 
The standard AZ part of the Dobsonian mount requires some getting use to when you try to track and object.  Even the special Az-El tracker motor systems can only track for short periods of time.
 
How about converting you Dobsonian to this PERRY WEDGE.  This can be made of many materials depending on how deep your pocket change might be.  All aluminum, stainless steel, or just plain wood.
 
Here are a series of photos of the Perry Wedge Equatorial conversion. Contact me if you would like one made or have any questions.

Equatorial Conversion of a Dob Az-El Mount
dobequatorial.jpg
Figure 3: Wood Equatorial wedge open view

dob-35base.jpg
Figure 4: Open view of Equatorial Wedge 4" and 5" PVC pipe fittings

You see the idea.  Just build a wedge of wood and screw some large PVC pipe fitting to the AZ base and insert it into the wedge.  The 4" PVC pipe fitting will fit with out machining into the 5" PVC pipe cup. Go to your local home plumbing store and get one each. Screw one to the Dobsonian AZ base of your telescope, and install the other one through the back of the wedge. You may have to do some cutting to get the dob to fit all the way in and run smoothly.
 
Here are anothe series of pictures showing how to improve the wedge.  The wedge can be made to fold up and work like the AZ-EL mount, or fold out and be a RA-DEC wedge.

wedg.jpg
Figure 5: The Folded Out RA-DEC wood wedge base

wedgcollaps.jpg
Figure 6: The folded down AZ-EL wood wedge

This last picture shows the side wood braces that fold down into the Wedge box. You hinidge the front wood, and the two side woods so they will fold down flat. The wedge then becomes the standar AZ-EL Dobsonian mount. Don't forget to make the angle of the front wood near your North Polar Latitude angle so the RA-DEC tracking will work.
 
You can add a wire drive to the PVC pipe that sticks through the front wood board.  This option has not been tried yet but should be doable. Use a large pully and wrap fishing stainless steel leader wire around it several times and wrap the other end of the wire around the small motor pully. That way you get some friction and it won't slip. If you want to machinea clutch system the fits over the PVC pipe that would be another added feature.

wedgfold.jpg
FIgure 7: Perry Wood Wedge being folded down into the box.

Novel 16" F4 using an OFF SET SINGLE FORK
16sidesaddle.jpg
This took some machining and tweeking

If you go to the obsurde size then you are looking into a whole nother animal in telescope design and ballance.
 
Here is my 32".  This started out with the glass required by a 27" mirror of standard thickness. I had Schott Glass of Jena press the 27" mirror into a 32" mirror with precurved F4. That sounded like a neat idea. Save the glass you would grind out and maximize the surface area.
 
So this primary mirror is 80cm in diameter but only 3.5" thick at the edge. The sagitta in the middle is about .7" deep. This mirror ended up F2.4.  This is the 3rd fastest known mirror in the WORLD. There are only two French 80cm mirrors that are slightly faster in F number for Schimdts.
 
Inorder to control the figure i ground and polished and figured the mirror on a large draper machine. I tested the polished surface by tipping the mirror up on its edge. Potatoe chiping of the mirror surface is noticable.
 
The first curve on the mirror is an 80 percent parabola, or ellipse. The Dall-Kirkam secondary is then a 6" sperical convext mirrror.  This gives the overall F# of F17.. Way Way too strong.  The new seconary to be done soon (20 years later) will be a 10" giving a total F# of F8. This should be more practical.
 
The image of jupiter at F17 is like 1" across.. Totally useless as the atmosphere is tearing up the image quality anyway.
 
Aligment of the 32"f2.4 with 6" secondary turned out to be much more critical than first thought.  Good images are not possible with Dall-Kirkam when the primary is less than F4.
 
The next step will be to refigure the primary to parabolic 107% Ritchey-Creitien formulae.  Then null the secondary as required. Some time in the year 2010 it might be done.

In 1972 this was the worlds largest amateur scope?
32inf2.jpg
The really big 80cm F2.4 with F17 secondary on Trailer