Hello, My name is Martin Rochette. I'm living in quebec city in eastern of Canada. I possess a big 17 1/2 inch Dobsonian telescope from Odyssey since 1990. My...
Martin, I had a problem with my dob on a platform also. When I would point it low to the horizon it would slip the platform to the end of its run. I had added...
Could anyone tell me how to calculate the diagonal size needed for any scope particularly one that is a 10 inch 4.925 focal lenght so that there is no...
Bill, There are plenty of programs that do exactly that. My favorite is the Newtonian Diagonal Calculator available as a free download from Woden Optics. Go...
Dale...try this: http://c3po.cochise.edu/astro/observatories04.htm Scroll down to second or third photo and see wife walking under the f/5.3, 36". Neal ... ...
Are there any sites with actual schematics also? in PDF or as a JPEG of so? Joel ... No virus found in this outgoing message. Checked by AVG Anti-Virus. ...
Hello John, The problem with my equatorial platform was that it was equiped a bad coupling between the motor drive and the wheel drive. Because the gravity...
Hello Bill, I have the book "The Dobsonian telescope-from Richard Berry".There is an article about "sizing the secondary mirror by calculation". I can to scan...
Thank you :) ... No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.300 / Virus Database: 266.5.7 - Release Date: 3/1/2005 ...
Someone whose address I have misplaced was asking recently about the use of Golf balls as bearings for their telescope. There is an article in Sky and...
The article you are referring too was about the sale of the land on which the "Big Ear" radio telescope of Ohio State University was located, near Delaware,...
I also recall that technique from an article over 20 years ago! Sounded very feasible to me too :) Dan NM ... the use of Golf balls as bearings for their...
Bill, Use this calculator: http://members.efn.org/~mbartels/tm/diagonal.htm Don Pensack ... any scope particularly one that is a 10 inch 4.925 focal lenght so ...
Would a tracking platform give less field rotation than alt-az tracking such as ServoCat/Sky Tracker? Logically, I would expect a platform to work a little...
Eddie, Well actually it is the other way around - when it comes to field rotation a platform is the only way to go (with a dob) to HELP to eliminate it....
A tracking platform _is_ (part of) the RA axis of a polar mount. Take a closer look at the geometry: imagine a big equatorial mount where the RA axis is a...
A proper designed tracking platform with the lightpad of the mirror being at the center of rotation one will have no field rotation. The lightpad of an EQ...
Thanks Gary, John, and Peter. My curiosity is satisfied. It's good to know that even without a platform, imaging is possible with derotation/alignment...
I've got a 25"F5 with a 3.5" secondary that seems peculiar. Here's the deal: when I use a laser collimator I see an abnormal number of red spots on the...
David, Dielectric coatings are, indeed, permanent, and have to be polished off. There is nothing wrong with the size of your diagonal, but the reflection...
The diagonals are designed to have highest reflectivity at 45 degrees angle of incidence. The Endurobright diagonals were also marketed as having a broad band...
Hello, May be you remember this scope : http://astrosurf.com/altaz/600_e.htm visible on this page : http://astrosurf.com/altaz/index_e.htm The owner as start...
Hi Frederic, Fantastique!!! Best Regards Gary Kopff Managing Director Wildcard Innovations Pty. Ltd. Home of the Argo Navis DTC 20 Kilmory Place Mount...
Frederic These are absolutely superb pictures for an equatorial platform!! Congratulations for your friends' efforts. Even at 30 seconds exposure the polar...
Hi, I am going to buy two eyepieces in the 9mm & 20mm range and was wondering if the Orion Epic eyepieces would be a good choice for my 18" DOB. They have...
You're not going to get the world's best edge-of-field performance on a big fast scope at these focal lengths, but you can have a lot of fun anyhow. My only...
