WTB: Dual Arm Astro Slew

elton · Post by **elton** » Wed Sep 13, 2006 2:57 pm

a 3-point finder-style mounting will allow adjustments in 2 axes which should be enough to roughly align the two scopes. There are a number of options for the Meg's mounting. Another possibility is to use a small photo head adapter like the one I sold to weixing which will give all the 2-axis adjustments you will ever need (just need to drill 3 holes in a small aluminium plate to make an adapter). Or, Jeremy can play around with shimming the contact points, or he can re-drill the M6 and M8 holes on the two arms to bring them to alignment in the alt axis. Nothing like a challenge to make it more fun

Canopus Lim · Post by **Canopus Lim** » Wed Sep 13, 2006 3:03 pm

Actually most people will not move the scope by themselves as they are too afraid to touch it. They will never get it centered as they don't have the experience to do that unless they are also fellow astronomers. So far for my friends who looked through my scopes, I will always place the object at the side of the field and let the object slide across. They will ask me to shift the scope if they don't see the object anymore.

I think Rlow is saying that a 2-axis (x,y) adjustment is necessary as even if the Megrez is 5 degree and the C8 is 1 degree max TFOV, they may not be in the same plane and it won't be aligned at all. A small difference in angle between the 2 arms will mean that both scopes are not pointing at the same object.

elton · Post by **elton** » Wed Sep 13, 2006 3:09 pm

Jeremy, you might want to check out a more elegent solution which makes use of the camera screw hole on the Meg.

http://www.losmandy.com/secondary.html#DCM

anat · Post by **anat** » Wed Sep 13, 2006 4:06 pm

Jeremy

You will need something like this. It is a low-profile two-axis adjustment adapter popularly used and engineered in Thailand. The guidescope ring cannot hold your scope well and maybe you will need to remove your dewshield or focuser to put it in.

Anat

rlow · Post by **rlow** » Thu Sep 14, 2006 1:27 pm

Elton and Canopus are right! A small photo head adapter may or may not work well because the scope is not mounted upright but at a horizontal level, which will then put a great strain on a small photo head adapter. Anat's guiding bracket is nice, how much is that?

Jeremy, if you want to consider as an alternative, I have a spare pair of 115 ID tube rings which you can modify and tapped for 3-screw adjustments.

anat · Post by **anat** » Thu Sep 14, 2006 1:56 pm

Richard

The adjustment bracket costs about S$200. The az and alt axes are adjusted using push-pull screws as seen from the photo.

kingkong · Post by **kingkong** » Wed Sep 20, 2006 10:42 am

just saw this article on cn. thought it might be a useful reference for what jerm is looking at doig...
read the "Unexpected Benefits" at the bottom of the article in:
http://www.cloudynights.com/item.php?item_id=1486

jermng · Post by **jermng** » Wed Sep 20, 2006 10:59 am

Thanks KingKong!
That's the article that pushed me to get the AstroSlew .. hee hee ..

river · Post by **river** » Wed Sep 20, 2006 12:06 pm

Yeap, the same article for me to get a dual arm.

anat · Post by **anat** » Wed Sep 20, 2006 12:12 pm

The same article made me sell you the mount and get an Eztouch to try

Anat