Basically, I could stop testingโ€ฆ finally! After 3 1/2 months reading manuals, forum exchange, adjusting almost everything, buying new equipment I reach now 100% sub exposures utilization. And after initial reluctance, I also adjusted the DEC axis stiction, which increased the DEC performance again.

Only the occasional dropouts/freezes/crashes are still happen sometimes! Even with the new MGEN cables.

Read more here about adjusting axis stiction:


I used the same setup like in Part V.

  • Dual 50mm Guide Scope 205mm f/4.1 with helical focusser
  • Canon EF 400mm mounted with original Canon ring
  • Canon EOS 70Da
  • Lacerta MGEN II
  • New set of MGEN cables
  • Powered by 12V 22Ah Power Tank
  • Payload weight: 5.25kg
  • Counterweights: 7.35kg

Session, Oct. 13, 2021

It was a bit dusty/cloudy, so I did only 6 test shots, each 10 minutes exposure time. Always after 2 exposures I changed some parameters to see a possible impact to the MGEN recodrings.

See below 6 x 10 minute exposures, taken one after another (cropped, 100% resolution). I like the stars on each of them ๐Ÿ™‚

MGEN Analysis Results

  • Axle Stiction Adjustment: -1/4 turn (before: -1/8)
  • Gear Meshing RA: -3/4 turn
  • Gear Meshing DEC: -5/4 turn
  • Guide Speed: RA 0.50x, DEC 0.25x
  • MGEN RA: NUM 1, Tol. 0.25, Aggr. 60%, Mode 2
  • MGEN DEC: NUM 1, Tol. 0.25, Aggr. 60%, Mode 2

The MGEN DEC star drift curve finally looks well ๐Ÿ™‚ Also the analysis of the raw data shows, that DEC is almost performing in the same range like RA. The point spread looks like a star cluster, as it should. Still not a perfect star cluster, but close ๐Ÿ˜‰

  • Guide Speed: RA 0.50x, DEC 0.50x (before: 0.25x)

The increased guidespeed to 0.50x shows a much better curve in some phases than with 0.25x.

Maybe I’ll adjust also the belt tension of the DEC axis, at least to see if that affects the measurements in some way. Even if I like the 10 minute exposures, the DEC curve still could be much smoother…

With this post the “GEM28 – Latest Update” series is closed. But I’ll continue doing measurements and if I find something interesting, of course I’ll share it here ๐Ÿ™‚

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