If you’ve ever built an imaging train and found out (at the worst possible moment) that your OAG + filter wheel combo causes back-clipping or awkward assembly headaches, the AstroAsis Oasis OAG (M48) is basically your “thank you” note to future-you. It was designed specifically to solve the back clipping problem users ran into with different camera brands and third-party OAGs—then evolved into a surprisingly clever, highly configurable guider with precision prism control and excellent light sealing.
Designed to avoid back-clipping issues commonly seen when pairing filter wheels + OAGs across different camera ecosystems
Configurable total thickness:16.5mm / 17.0mm / 17.5mm to hit backfocus targets without creative spacing hacks
Double-helix focusing mount does two jobs:
Focus the guide camera
Precisely adjust prism height/position without disassembling your imaging train
Multi-brand filter wheel compatibility thanks to multiple mounting hole patterns
Strong emphasis on light blocking and sealing between the OAG, adapters, and filter wheel—designed to reduce internal reflections and light leaks
Optional motorized guide camera focusing via the add-on kit (for remote/observatory users who don’t want to touch anything at 2 a.m.)
Precision prism adjustment (the “secret sauce”)
The prism pillar uses M28.5x0.6 external threads, matching the common M28.5x0.6 internal thread found on many guide cameras
You can raise/lower the prism using the dial on the double-helix mount:
6mm total travel per full dial rotation
1mm per large graduation (0–5 markings)
0.05mm per small graduation (20 subdivisions per 1mm)
Start position reference: with travel set to minimum and prism fully down, distance from prism front edge to optical axis center is 8mm
Adjustments can be made fully assembled on the scope, even at night, without breaking the imaging train
Specifications
Product type: Off-Axis Guider (OAG), M48 system
Prism size:8mm x 14mm
Prism coating: Anti-reflective coating on both sides
Configurable thickness:16.5mm / 17.0mm / 17.5mm
OAG body thickness: 12mm
Uses threaded couplings of 4.5mm / 5.0mm / 5.5mm to reach total thickness options
Each thread set includes 3 coupling thicknesses: 4.5 / 5.0 / 5.5mm
Kit includes one set of couplings (thread type specified as M68, M54, or M48)
Focusing/prism adjustment mechanism: Double-helix focusing mount
Travel: 6mm per full rotation
Adjustment resolution: 0.05mm per small graduation
Guide camera interface (common standard): Prism pillar front uses M28.5x0.6 external thread
Filter wheel compatibility (as provided): MokKong / Ready Player One / QHYCCD / TuPu (Graph) / Zhenwang
Light sealing features: O-ring recesses, plug-able unused threaded holes, extension ring grooves for sealing
Special assembly benefit (7x2 filter wheel use case): Designed to avoid housing screws so disassembly/cleaning can be done without removing the OAG (specific to the mentioned 7x2" wheel scenario)
What’s in the box?
AstroAsis Oasis OAG body (M48 system)
Prism assembly (8mm x 14mm, AR-coated)
Double-helix focusing mount (guide camera focus + prism height control)
One set of telescope-side threaded couplings (choose/specify thread: M68, M54, or M48)
Includes 4.5mm / 5.0mm / 5.5mm thickness options
Set screws / hardware provisions for plugging unused mounting holes (for light leak prevention)
Software and Docs
None required (hardware OAG)
Optional accessory: Motorized focusing kit (Mikkuri/MokkElectric-style kit) for motorized guide camera focusing via belt drive (ideal for remote setups)
Optional spacing note (from provided info): For short backfocus cameras (example given: QHY268), an optional 5mm extension ring can be placed between the OAG and filter wheel to meet backfocus requirements.
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