The SXV-AO: Active Optics for the SX Camera User

Details 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 12 VDC when moving - 50 mA quiescent current. Compact and lightweight - only 112mm in diameter x 32mm long - less than 500 grams load on the 'scope. < Top  |  Sample Images >

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.

Sample Images

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.
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 f/10.

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The SXV-M8C images below were taken with a Celestron Ultima 8"
on a fork mount with poor polar alignment and rapid gear errors
at an EFL of ~1260mm, giving a resolution of about ½ arcsec per pixel.
Images are shown at 1/8 size. Exposure time was 10 minutes.
 
Click on images for full-size versions (these open in a new browser window).

M42 without AO guiding.   < Top  |  < Details

M42 with AO guiding. The little coloured spikes on the bright stars were caused by the AO turning off just before image download.