[BadWolf (Stewart)]

I acquired a new SW EQM35 (payload said to be 10kg) mount a few months ago, and it is paired with a SW80ED scope (weight about 2.5kg and length no more than around 600mm). The setup works very smoothly and efficiently.



GoTo has been very good once I finally found a way to find the Celestial South Pole (time lapse star trail photo, and reference that image to a couple of trees). Not a chance in hell of finding Sigma Octanis through the inbulit polar alignment scope under Brisbane skies!! On a good night, if I have aligned it properly, the EQM35 GoTo can put the object within the FOV of my Baader 21mm eyepiece, or at least in the 8 x 50 finderscope FOV on a bad alignment night. I use the Skyscan 3 star alignment, then the Polar Alignment process.Happy enough with that.


My question to this forum relates to payload capacity and more so the payload physical size. I purchased an inexpensive Skywatcher 120mm Achromat - f/8.3 (1000mm FL). Reason being a larger aperture for viewing double stars and planetary observing. It is about 4kg and 1 metre long.



(As an aside, I know that chromatic aberration can be an issue, however I placed a 2 inch Baader Fringe Killer filter as a "permanent" fixture screwed into the star diagonal box, and any blue/violet is now gone - even with the lunar limb and shadows inside craters.)



I digress - on to the question. The 120mm seems to work on the mount quite well with no apparent extra effort needed by the mount, however there seems to be a bit of "play" or wobble in the Dec axis when the scope is at rest. The ED80 does not seem to have that slackness. I think that possibly a scope of that length is not really suited to the EQM35 - not too heavy, but maybe too long which could introduce a shift in the weight distribution causing the slight wobble. The wobble could also be something loose in the Dec axis assembly, that becomes more apparent with the extra size of the 120mm?? Any information or comment from those who experience it these matters would be appreciated.