OGMA OAG M48 Off-Axis Guider with Helical Focuser and 1.25" Holder
The OAGM48 Off-Axis Guider is a crucial instrument that allows astrophotographers to use the same telescope for guiding and imaging.
After adding the OAGM48 to your imaging train, the 10x10mm prism inside the Off-Axis Guider will redirect a portion of the star field that usually doesn't fall on the primary camera sensor to a guiding camera inserted into the 1.25'' holder.
This Off-Axis Guider has an M48 thread on the side of the telescope and multiple tapped holes on the side of the camera. These holes are designed to match most filter wheels currently available in the market.
Highlights
The size of the prism is a generous 10x10mm.
The Off-axis guider consumes 17.5mm of back focus.
The OAGM48 can be used with or without a filter wheel.
If you don't have a filter wheel or a Universal Filter Drawer, you can use the 20mm width spacer that comes in the package between the camera and the Off-axis guider, to help you achieve proper back focus simultaneously on both, the main and the guiding cameras.
The smooth helical focuser will help you achieve precise focus with your guiding camera.
The prism can be moved up and down for a precise placement.
Assembly
If you don't use a filter wheel or a filter holder, use the included adapter between the OAG and the primary camera. This will help you achieve the required back focus for your guide camera.
Remember that if your primary camera doesn't have a UV/IR window, you must use a filter wheel or a filter holder with the right filter; otherwise, you won't get sharp stars.
Dimensions
Dimensions of the OAGM48 Off-Axis Guider with the front plate connected
Note: The Off-axis guider consumes 17.5mm of back focus when fully assembled, including the front plate.
Adapter
Dimensions of the adapter included with the OAGM48
If you don't use a filter wheel or a filter holder, you can use the included adapter between the OAG and the camera to achieve the correct back focus of both the guiding and the main cameras.
You won't need this adapter if you use a filter wheel or a filter holder.
The preferred method for connecting this adapter is by using the provided screws to bolt it to the front of the camera. Then, bolt the OAG to the adapter.
For cameras that don't have the six threaded holes in the front, this adapter has an M54(f) thread on the camera's side, and an M48(f) thread on the OAG's side.
Installation
In the last part of this video, you can see how the OAG is connected to a filter wheel.
If you don't have a filter wheel and want to use the OAG, we recommend using the OGMA Universal Filter Drawer in place of the filter wheel. It is the easiest way to ensure that the OAG's prism will be placed correctly.