Growing Pains

The new mount outlined in my last post has turned into a love-hate affair. It can certainly carry more weight than my Atlas Pro, and when it works, it works very well. I've seen the guiding perform just as well with the new mount carrying 60+ pounds, compared to the Atlas Pro carrying about 25 pounds. After having two months to work with the new mount, I think I've had it long enough to write an unbiased review, and discuss what I believe to be a design flaw in the EQ8/HDX110 mount.

The main problems that I'm seeing stem from, in my opinion, both the RA and Dec motors hanging off the west side of the mount (as seen in northern hemisphere with mount pointing toward Polaris).

First of all, I need to say I did not buy the polar scope that hangs off the opposite side of the mount. From what I can tell, the brackets look to be fairly thick and heavy, and these brackets combined with the polar scope itself, could balance the mount. As it is now, I can balance RA to be quite a bit east heavy, and when I release the counterweight shaft, it will fall down to about a 30 degree angle before the weight off the motors cancel things out. When I say "quite a bit east heavy", I mean very east heavy compared to what I've always done with the Atlas Pro and CGEM DX mounts. I'm afraid to go any further with it. This graph sums up what I've been seeing at times. It seems to always occur in this "dead zone" pointing east where the weight of the motors cancels out the weight of the counterweight(s). It also happens right after flipping meridian. I can move the counterweight down the bar after the meridian flip and it stops happening, but guiding is not nearly as good.

I first tried to go about things by offsetting the scopes to the east a little. I bought an ADM side-by-side saddle and loaded up the mount with my 10" Meade SCT, TS 107mm, and WO Star71.

It worked reasonably well most of the time, and then I'd see RA taking off on its own. First one direction, and then the other. When this starts happening it usually takes me an hour to get in a single 10 minute exposure. It gets very frustrating as you might imagine.

Apparently this is nothing new to EQ8/HDX110 owners, because I ran across these images in Stargazer's Lounge showing what others have done.

Since these dont show the polar scope attached, it really makes me think the weight of the polar scope and brackets hanging off the side balances things out. I really dont see any other reason a polar scope would be mounted in this fashion. I question its accuracy mounted in this configuration as well. I will try something as pictured above and report back. Again, when it works, it works great, and should allow me to buy and use a larger carbon truss RC that I have been wanting.

Guiding with 0.29" rms total error

 At least its warmer now with Spring in full swing here. I'm hoping to get this nailed down soon and purchase a new large aperture scope for imaging. Hopefully it happens soon, because I otherwise really do like the mount. Wish me luck, and happy imaging everyone!