M75 Helical Focuser & PM-1X Mount

I replaced the conventional helical focuser with M75 one. Now I doesn’t matter what a heavy equipment is set at the back end. Extra benefit is to make OTA weight balance easier.

0718c Focusing is very smooth entire focusing range too. Well machined and built up by the Japanese “TAKUMI” technique.

As described before, the focuser’s helical mechanism has very fine pitch. The outer diameter of a rubber section is about 98mm. Rotating a rubber section 15mm (18 degree) moves ONLY 1mm!! back and forth. Imagine how fine movement is while twisting 15mm or 18 degree by your hand. This should really help the precise focusing. So feel like 15:1 reduction??


We plan to prepare for M75 focuser packages for 71FL and 90FL.

BTW, the total weight of whole imaging set shown below is about 6kg. A cooled camera is heavy.


But PM-1XGEM (Hutech part #) looks handling much more load weight. I don’t hesitate loading BORG 107FL either. A good advantage of Hutech special arrangement is the equipment from the mount axis is much closer than the Takahashi original setup. See the comparison.

Less DEC unit weight itself and closer to the mount axis point. This achieves less counterweight or more loading the gear. As shown in a picture, two counterweights (1.4kg each) still have a plenty of room for more equipment weight.  For the imaging purpose, I love this setup. For visual use, yes the original DEC unit makes handling much more convenient. DEC slow motion knob is still nice for image composing too. But as long as it is short focal length, I don’t think it’s so critical. It should be still manageable.


~ by tedishikawa on July 18, 2016.

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