[billdan (Bill)]

Hi Peter,

Thank you for your insight and experience you have had with the SBIG AO-X, and a 30% improvement in FWHM is at least something that is a step in the right direction.

I was not suggesting that mount corrections were happening at 15Hz or higher, however the tip/tilt optical window is operating at that rate and a guide pulse to mount may only be once every 4 or 5 secs.

When I looked into these AO units in 2014, I ignored the SBIG product because you could only use their guide cameras and you had to use Maxim software.

The other two that were available back then ($1600 ea) was the Starlight Express SXV-AO and the Orion Steadystar AO, both of them claiming to provide up to 40Hz correction to the tip/tilt window.

Orion has discontinued their product but you can still purchase the Starlight Express unit. Except its old technology that uses a RS232 port as its interface to the computer, Orion used a USB port.

In the end I rejected both of them because of the amount of backfocus they steal (70mm for the Starlight Express and 45mm for the Orion both including the integrated OAG).

This was the sales blurb for the Orion Steadystar:-

SteadyStar's high-speed refractive correction eliminates tracking errors far more effectively than regular autoguiding, resulting in better astrophotos with rounder and more pinpoint stars

Fastest adaptive optics guider (used for amateur astrophotography) on the market today! Capable of making more than 40 corrections per second, depending on guide star brightness and computer speed to overcome your mount's periodic error, combat wind-induced vibration, and even compensate for some of the negative effects of turbulent seeing.


Bill