SWG mounts are not like worm gear mount nor are they the same as each other of the same brand mount or different brands either. SW Gears are individually unique in harmonics, slope and PE. Asiair or Phd2 standard settings are not ideal for SWG mounts. SWG mounts will always benefit from bigger guide scopes, great guide focus and bigger, better guide cameras. Some mounts are great at any settings while others need lots of change from standard settings. Asiair settings of 2000, 2000, 2000 are not ideal for SWG mounts. Sometimes a higher gain using multistar guiding will weed out oversaturated stars as you want to get as many same weight stars as possible using multistar guiding. Some SWG mounts run fine with OAG’s but others do not like stars that have “bat wings” but rather a precise round star centroid. Fast mounts like fast but small corrections.
These harmonic drive/ strain wave gear mounts require faster guide exposures than worm gear mounts. They seem to do better on Phd2 ecosystems than asiair due to different means of how asiair chooses non equal size stars for multistar guiding.
The SWG mounts require smaller Ra and Dec durations and less aggressions. Calculate your worst and sharpest slope from the ZWO partial graph to determine how good or bad it is. These mounts also require half the amount of MinMo than worm gear mounts, usually below 0.1 px. Each SWG mount is unique and how fast you need to guide is based on how fast the worst part of the PE slope is and not how big the total PE is. The graphs supplied are not very useful as the fastest slope may not even be located in the partial graph and the partial graph is only the highest PE area and that is not as important as slope.
The biggest issue with fast guide exposures is that 0.5-1.0 second guide exposures produce less guide star signal, hence the need for bigger, better and brighter guide imaging components.
These are just a few things that people need to know about SW Gear mounts that I have documented from research and mostly from people much smarter than myself.
My settings for a base setting will not be the same as your mount or some other persons mount but from looking at many other peoples SWG data, a generalized baseline setting list could be…
Guide exposure length - 0.5 - 1.0 second
Max Ra Duration - 300 to 700ms
Max Dec Duration - 300-700ms
Ra Aggression - 35-55%
Dec Aggression - 35-55%
Minmo - 0.1px to 0.15px
Calibration step size - based solely on guide scope FL and guide camera pixel size. Phd2 brain can calculate it for you under advanced guide tab.
These are just generalized settings that is a good starting point to get you in the general area and try to get 12 stars using multistar guiding… bump up the gain if you need to. I hope this will help anyone new to guiding a Strain wave/ harmonic mount.
Clear skies.
Cheers,
Kevin_A
