Stockton Astronomical Society
Valley Skies - January 2000 Issue
The Telescope Nut
by Jeff Baldwin
What's Next in ATM Madness?
When I was 16, a big scope was 12.5". That would be the largest telescope in your astronomy club. Of course I helped build a couple of 16" scopes just to pop the limit. Then came Gary. He had a 17.5" scope. Of course me, with my telescope envy, had to build a larger scope. My friend Dan and I worked on 17" scopes together. They weren't larger, but they were really big to us then.
When I came to California I had already begun the optical brainstorming for the 24" Black. That held me for nearly a decade. Black is gone now, and work on the 40" scope is about to go to full scale. My friend Dan in Spokane has done a 34" and a 41". My friends Bruce and Steve have a 40", Mel has a 32", and there are lots of 1 meter class scopes across the country now.
So what's next? Where will ATM go from here? A 12.5" used to be about as big as they got, and now there seems to be 40" scopes popping up in each corner of the country. Will they continue to get bigger, or will things start moving some other direction?
Here are a few ideas I have: Lower foci, larger standard sizing for focusers, crazy designs from ray-tracing, and rubber mirrors.
Most areas now have at least one scope that exceeds 20", if not 36" to 40". The main problem with these scopes, other than transporting them, is climbing a 16' ladder in the dark to gawk through them. With current ray-tracing programs, most medium to heavy duty designers can calculate the optics for folded cassegrain type Dobsonians. Instead of a 40" f/4 Dobsonian, it would be a 40" f/2.5 mirror, a cassegrain secondary mirror that boosts the focal ratio to around f/7, then a tertiary mirror that shoots that focus out the altitude bearing. This would be a non-moving focus at a convenient height. One design right now has a small refractor mounted at this area to image the view. This will allow those folks who don't want to climb a tall ladder in the dark to view through a 1 meter telescope.
Larger Standard Focusers:
Standard American focuser sizes are 1.25" and 2". The standard Japanese size is 29/32", or 0.965". These have gotten us through thick and thin for a long time. However, TeleVue has just released their latest, and probably their greatest eyepiece, the 31mm Nagler. It allows an 82° field of view in a 2" eyepiece. The only thing keeping them from making a larger Nagler now is that the field of view of a larger Nagler would need more than a 2" barrel to sample the sky. OK, to get this remarkable eyepiece you would need, say, a 3" eyepiece standard. Can you imagine looking through a 40mm Nagler, or a 50mm Nagler? There is only one way to do it and that is with larger focuser diameters.
With the ray-tracing programs available now, armchair opticians are coming up with awesome designs of exotic telescopes. This is good. Eventually somebody is going to run into the wonder scope and they will get rich selling it because it will make everything before it obsolete. That's good. This kind of imaginative messing around with light got us the Maksutov, apochromatic refractors, and even Schmidt cassegrains. Can you imagine the astronomy market without Celestron or Meade? I can't.
Large observatories are now using adaptive optics in their imaging. This means that when the atmosphere screws up the image a high speed device changes the shape of the small mirror, correcting the image before it arrives at the ccd. This gives the large ground-based telescope nearly the resolution of the Hubble. Eventually this technology will become affordable to the guys who are using ccd's to image deep sky and planetary pictures, and amateur astrophotography will take another giant leap forward.
For everything that I can think of that could happen to improve telescopes, there are a zillion other things that I can't think of, and those will be the inventions that keep our hobby going in the future.
Clear Skies...Jeff Baldwin
For more information on Telescope Making jump to the ATM page.
Copyright © 2001 by Jeff Baldwin
Last Updated: 2/28/2001