[ap-gto] Will the Mach 2 support

Harley Davidson

Thanks for the information and photo Roland!


On 6/1/2021 8:06 PM, Roland Christen via groups.io wrote:
Hello AstroNuts,

We get this question many times, "will the Mach2 support my scope, camera etc." I can't really answer specific setups since I don't have infinite variety of scopes at my disposal. However, to give you some idea I am presently testing two scopes piggybacked on the Mach2.

Here is my present setup. I am using it to test various optics, cameras and field flatteners. It consists of a 160EDF refractor with QTCC and a full frame ZWO 6200 color camera, which provides a very wide field. On top rides an oldie but excellent 130 EDF refractor with 2.7" focuser, 67PF562 Flattener and my QSI 683WSG camera, Lodestar off-axis guider and an 8x50 Baader finder for good measure. Both scopes sit in rings that are attached to dovetail plates. When you add up all the parts, the whole shebang weighs close to 70 lb with the weight centered about 9 inches from the top of the Dec axis. I have approximately 75lb worth of counterweight which includes the weight of the standard Mach2 cwt bar and the shorter extension.

Is it stable and does it slew, track and guide effortlessly? Yes on all counts. It does need to be closely balanced, but not ridiculously so. Using MaximDL6, in poor seeing i get on the order of 0.4 arc sec rms guiding. In good to excellent seeing I get 0.1 to 0.15 arc sec rms guiding. My guide exposure is between 2 and 5 seconds with 1.5 seconds between exposures. Best guiding seems to be when the exposures are 4 to 5 seconds, and I get very few excursions that are larger than 0.5 arc sec pk.

By the way, I don't usually guide with one scope and image with another. In this case I am guiding with the lighter weight 130EDF and I am getting perfect round stars with the 160 below. The 160 is shooting at 960mm focal length with a 3.75 micron/pixel camera, 0.8 arc sec per pixel. ZWO 6200 camera. resolution with this camera in medium seeing has yielded 1.4 arc sec FWHM stars in a 5 minute exposure.

I will be shooting tonight if the weather holds, and I can record some guide graphs for anyone interested. Seeing is supposed to be good (4 out of 5) but transparency will be poor. I'm doing a shootout between the CMOS camera with 3.75 micron pixels and my older QSI683 CCD camera with 5.4 micron pixels. Which camera records images faster? Which has better contrast? Any bets on the winner?


Roland Christen