Hi,
ich habe natürlich Google Übersetzer bemüht ,aber da kommt nur grausames Deutsch raus[V]
hier der Text
Good point Dan. In this case, waaaay up there.
Having built and housed several large, long focal length achromats with straight thru tube assemblies, I found it relatively straight forward with the most difficult task really being adjusting myself to, and thinking about, the shear scale of such a project. I literally had to "think big". And I had to do a lot of the "M" thing, called math, but that was mostly the big four (addition, subtraction, multiplication and division) and yes, a bit of algebra too.
The 11' F12 is housed in a roll off roof observatory. Its walls are~ 10 foot high. So it went something like this:
1. Balancing the scope at ~ mid point gave an ~5.5 foot length, but I also wanted the eyepiece when pointed straight up to be at least 3 foot off of the floor for reasonably comfortable seated viewing. So, I'm now at 8.5 foot.
2. The scope's OTA was to be "parked" parallel to the floor. Now with the rings, finders and other stuff attached, measuring from the center line of the OTA to the farthest out point that that other "stuff reached, I needed a little over another foot. So, I'm at 9.5'
3. Add to that (the math thing) the wall headers and footers and I'm at 10 foot.
4. Additional running clearance between the ceiling and that furthest projection from the scope centerline was provided by the steel and casters for the rolling roof. Total running clearance is ~ one foot.
5. Once that stuff was figured out, the next biggest elephant in the room was the mounting. I already had it (a Parallax HD250 Observatory series mount) so I knew its dimensions when in the "park" position. But I needed an adapter to attach it the pier top and allow for adjustments in altitude and azimuth. Once designed and fabricated (using math), I could measure its height.
6. I now had the information to calculate my pier height.
7. Done....with the scope assembly design anyway.
Now consider an OTA for the 12" F16.6. The OTA will be ~ six feet longer than mine. That means the walls would be ~ 13 foot high. I don't like heights. At that height, you may well be using structural steel or a reinforced concrete block knee wall with conventional framing. But then with a roll off roof, you have to consider the stability of the walls against bowing in the middle. Steel is really handy for that....but expensive so again, super sizing your thinking, this time financially, is required. And I have not even mentioned getting to the eyepiece when viewing stuff low in the sky, like the planets this year (I went to visit the old observatory here in Cincinnati to get ideas for that).
But it can be done if you just think things through, super-size your thought process (and yes, your wallet) and take-your-time. What you end up with though, will be an installation that will be first rate, last a lifetime (and more actually) and be an incredibly satisfying scope to use.
Danke im Voraus
hier der Link um die Thematik zu verstehen [:)]
