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Digital Setting Circles and Dob leveling

Started by [email protected], 10/23/2003 12:55PM
Posted 10/23/2003 12:55PM Opening Post
Hi all --

My 18" Dob and DSC's have been a joy but DSC accuracy has varied some from viewing session to viewing session. I've assumed that the variations have been related to my two star alignments but I wonder about scope leveling as a factor.
Does anyone know how critical leveling is? And how do you level your scope? For those of us who don't have a permanent scope pad this could be an important issue.
Thanks for all help.

Bob Polcyn
Posted 10/23/2003 01:14PM #1
Bob,
Not sure which DSCs you are using, but I will assume it is the Sky Commander since the Tangent boxes and the Argo Navis do require leveling the scope; or at least inputting the angle of the scope. While the SC doesn't *require* leveling and inputting the angle of the scope, I do like to get mine as close to level as possible, and I at least *think* that I get better results because of that. I just stick a bubble level in the bottom of my rocker box to check that it is level, and then use some shim stock under the feet if it isn't level. At home I am on a permanent pad, but when I go to my club's site, I find this procedure necessary.

Also keep in mind that all of the DSCs on the market, or at least the ones that I have used (AN and Sky Commander) will lose some accuracy over the course of the night. I am told that this is just the way it goes when using the optical encoders currently on the market. I do find that doing a "realign on object" gets me back on track for the most part.

Doug
Midway, FL
Posted 10/23/2003 05:05PM #2
Bob,
I agree with Doug on this. Leveling is a good idea even if not necessary acording to instructions manuals.
Also, the realigning on an object in the area of your observations is always good for acurracy. So if you are going to look a number of objects in a section of sky, go to an object in the center of that area and then realign on it.
If you are having problems in slewing you may have the tick count too high and are loosing ticks because of fast movements. The 4000 tick encoders are less likely to do this than 8000 tick encoders. You can adjust the tick count in the setup. Trying different settings may help, you can always put it back to original settings.
If you have to deal with "Warp" factors with your DSC, then this is the source of the problem most likely. Some DSCs require you to set the perpendicular axis (Tube straight up)of the scope. Then it gives you a warp factor that must be within limits. If you are gettin a high warp, this will cause inaccurate go-to. This is best adressed with a level surface and marks made on the scope after you have found "true perpendicular" in the tube.
Hope this all helps.
Floyd

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
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