The SXV-AO

Active optics for the SX camera user

The AO unit with the off-axis guider and guide camera attached

• Image tracking and stabilisation using a high speed tip-tilt optical window

• Fast tracking speed of 5mS per increment

• Overcomes rapid gear errors to stabilise even difficult mounts

• Mount control output for correcting large drive errors while maintaining AO stabilisation

• Image shift factor independent of optical system or camera back-focus spacing

• Off-axis guider assembly (optional) for use with an SXV guide camera

• STAR2000 guiding compatible

• May be used to image stabilise many other makes and types of camera, given suitable control software

• Clear aperture of 37mm for up to APS size chips

• Short optical length - 64mm with OAG, 38mm without.

• Very low light loss (~2%) from the multicoated optics

• Filter recess for adding narrow band. IR blocking or pollution rejection filters without affecting the guide camera sensitivity

• Serial RS232 control via the computer or SXV splitter box. Parallel control available

• Low power consumption. Less than 600 mA at 12v DC when moving - 50mA quiescent current

• Compact and lightweight - only 112mm in diameter x 32mm long - less than 500 grams load on the 'scope

A view of the OAG assembly. 

The camera mounting ring, pick-off prism adjuster and power socket are visible.

The SXV-AO should be used with the off-axis guider for the best results with most optical systems. This combination uses an SXV guide head to view the edge of the telescope field via a 10mm square prism and provides accurate positional feedback to the control software. Unlike cameras with an integrated guider chip, the OAG puts the guide camera ahead of any filters that the user fits into the camera ring recess and so its sensitivity is always at maximum. The guide camera mounting is designed to be parfocal with an SX camera when used in this combination - fine focus adjustment is provided by moving the threaded guider mount along the prism tube.

STAR2000 cameras may be used directly without the OAG, but the AO correction rate must be kept reasonably slow, or amplifier glow effects may become a serious issue.

A front view, showing the imaging and guide camera CCDs, along with the input and output connections.

Some examples of the AO in use

No processing was applied, other than cropping, so that the images are essentially 'raw'

The mount used was a Celestron CI700 with a C11 SCT at F10

A 2x enlarged clip from an SXV-H9 image. Ten minutes with a C11 at F10 using mount guiding only

Another clip taken a few minutes later with the AO switched on and operating at 3 updates per second.

Here are some 'extreme' images from an Ultima 2000 on a fork mount with poor polar alignment and rapid gear errors. 

The camera was an SXV-M8C and the images have been resampled to 50% of full size for display

Without AO correction

With the AO switched on

(The short coloured spikes on the bright stars were produced when the AO switched off for image download)

Download the latest SXV-AO driver software

Run AOupdater.exe to install the software and copy the hex file to the hex folder. Instructions are included as a text file. 

The current hex version is issue 18.