Full Frame On-Axis Guider ONAG® XM Lambda for exo-planet and photometric work (unit only)


ONAG® XM Lambda for full frame chips, up to 50mm in diagonal (unit only)
For exo-planet transit and photometric works with UBVRI filter system.


For exo-planet transit and photometric works with UBVRI filter system or equivalent.

This is the ONAG XM Lambda unit only, please see our accessories for standard spacers and adapters.

For ONAG backfocus calculation and Excel spreadsheet click here.

The ONAG XM Lambda is the new full frame (up to 50mm diagonal) member of our On Axis Guider product line.
It has been designed for photo-metric work, such as exo-planet transit.
Here are some related papers:

Achieving High Precision Transit Observations with Sub-meter Telescopes, Dennis M. Conti
Use of On-axis Guiding toReduce the Effects ofPolar Misalignment on Field Rotation, Gaston Baudat

This version of the ONAG XM has a transition wavelength at 700nm where the I band filter starts in the photo-metric UBVRI filter system.

ONAG XM Lambda transition curve

This allows using the ONAG with two cameras with UBVRI filters,. The imaging camera for the UVBR filters and the guiding camera for the I-band.
We recommend using our astigmatism corrector in this context. Accessing, in same time, both the visible and the I-band allows to monitor exo-planet transits in two bands for detection of false positives, hence double stars, without drooping the sampling rate by changing filters.

It is fully compatible with the ONAG XM therefore you can use the same adapters and spacers than for the XM version.
When associated with FocusLock software it offers an unique solution for guiding and continuous real time auto-focus using our SharpLock patent pending technology. There is no need to interrupt your imaging session for any periodic re-focusing runs anymore.
SkyGuide/SkyGuard full frame software offers a total new approach without any specific guide star for guiding and focusing.

It is equipped with a guider helical focuser for fine focus (800 microns for 360 degrees of focus ring rotation) associated with a new X/Y stage for the guider port (GP).
This stage has been engineered to support larger, and heavier, guiding cameras with large field of view (FOV) for remote operations. The ONAG XM Lambda guider focuser supports APS-C chips with diagonal up to 28mm, such as the popular KAF8300, or large CMOS sensors.
A large guider FOV provides access to many guide stars without using the integrated ONAG X/Y stage.
To know more about our  patented ONAG technology please visit our eduction page on this matter.

Innovations Foresight recognizes that ONAG’s users may want to customize their ONAG solution to fit their setups, as well as to use adapters/spacers they may already own.

The ONAG XM Lambda is optimized for full frame, up to 50mm in diagonal, imaging chips.
The ONAG XM Lambda scope and imaging ports (SP, IP) use a 59mm dovetail system for rigid connections with the scope imaging train (focuser, rotator, focal reducer, …) and imaging/filter wheel equipments.
The ONAG XM Lambda guide port uses a T2 (M42 x 0.75mm) male thread for connection to a guider camera.

To fit your needs Preciseparts.com provides custom adapters for any of our ONAG.

For fast scopes with f/#<8 and/or large central obstructions (>35%) we recommend considering our astigmatism corrector. When used with the continuous real time auto focus software FocusLock (FL) the corrector can be rotated to dial back some controlled level of astigmatism.
Since SkyGaurd doe snot use any centroid it is immune to astigmatism and therefore can work with most scope without the corrector.

Fell free to contact us for any advice and support.

Watch the ONAG technology video below:


  • Finding a guide star has never been easier!
  • For your best images yet, ONAG Features:
  • Wide FOV for your guider with the integrated X/Y stage.
  • No differential flexure even with long focal lengths.
  • NIR guiding for reduced seeing & a smooth tracking.
  • No rotation needed, enjoy reusing your flat frames.
  • No filter in the way, ideal for narrow band imaging.
  • Sharp images with SharpLock our real time autofocus.
  • No periodic refocus anymore, save time with SharpLock.
  • Light weight (0.8 Kg) and much more…

Typical specifications:

Product Specifications: without extension tube
Over all dimensions: 123 x 110 x 70 mm
ONAG® weight: 850 g
Imager back focus: 68 +/-2 mm
Guider back focus, half way extended: 101 +/-1 mm
Imager chip diagonal: Up to 50mm (full frame, 36x36mm, …)
X/Y stage, full X travel: 37 mm
X/Y stage, full Y travel (excepted low profile): 24 mm
X/Y stage, maximum off-axis offset: 22 mm
X/Y stage maximum exploration circle: 44 mm
Guider focuser type: Helical
Guider focuser travel: Minimum 9 mm
Scope port: Dovetail 59mm
Imager port: Dovetail 59mm
Guider port: T-thread (M42 x 0.75)
Dichroic beam splitter coating: Fully multi-coated
Dichroic beam splitter protection (both sides): Optical grade quartz
Typical dichroic beam splitter reflection (visible): > 98%
Dichroic beam splitter visible range: > 370 nm to 700 nm
Typical dichroic beam splitter transmission (NIR): > 90%
Dichroic beam splitter NIR range: > 700 nm to 1200 nm
Anodizing: Black, low reflection
Guider port corrective optics No
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