Wedge for 16" LX200

Hi all,

I need some last minute comments before I go and spend some money.

After several years of fiddling, I have decided to replace the field de-rotator with a wedge on the 16" LX200 scope. Meade does not make one. One on-line source has a ~4+ month wait. Another on-line source is way out of the price range. So... There is a local welder that makes piers for a local scope shop and I understand the turn-around time is very fast, and the cost is very reasonable. I have made a cardboard prototype, and am ready to hand it over. The plan was a 1/2" base and other parts 3/8" steel welded into a "box", with an adjustable diagonal plate. (Heavy!) The azimuth adjustment will be two "tabs" under the base plate, and the altitude adjustment will be two screws pushing up from the bottom of the plate that holds the scope. The scope plate will pivot at the top. The photo shows the general design. It is offset so the center of mass will be over the center of the pier.

Comments? Questions? Feedback? (I also posted on the Equipment Forum)

Thanks
Charlie

Attached Image:

You may find that converting your fork mounted scope from Alt-Az to Polar will make the entire system even more unstable. Yes, theoretically it will be easier to guide, but this fork system is in balance when mounted in an alt-az configuration. Once you polar mount it, the upper bearings in the Dec axis will have to take both radial and tangential loads (in alt-az they only take radial loads, which is what they are primarily designed to do). It's the tangential loads that will cause your scope to shift and twist in different parts of the sky.

Remember, you are trying to aim your optical system to the arc second level, and that means that there is no room for any deviations during tracking and guiding.

What many people fail to realize is that yes, larger apertures have the potential for higher resolution, but this also placees greater demands on the accuracy of the mounting system. You would be better off to place this tube assembly on a large GEM. If you do decide to get a wedge system, and you want to approach or exceed the resolution of a mere 6 inch instrument, you will probably need to use an AO7 or AO8. (remember, I said RESOLUTION - light grasp you have plenty of, and you can fill any CCD chip with lots of light with that size scope, but is the image quality going to be there also?)

Rolando