OGMA Universal Filter Drawer (UFD) for Off-axis Guider (OAG)

Highlights

When using an OAG, it's crucial to position the OAG's prism exactly above the camera sensor. Traditional filter drawers often pose a challenge in predicting the final prism position of an OAG because they are connected to the imaging train using a large thread at the center. While tightening the tread, it is hard to know the final position of the prism.

This OGMA UFD can be connected using screws that are precisely placed to make sure that the prism of the OAG will fall at the required angle, consistently—no more guessing where the prism will be after tightening the threads.

Compatibility

This is a preliminary list:

  • All cooled OGMA cameras
  • Most cooled cameras from Touptek
  • Most cooled ZWO cameras featuring six M2.5 screw holes distributed around a 62mm circumference on the front face around the sensor
  • Some Player One cameras

We will continue expanding this list.

Back Focus Considerations

This product can take either 20mm or 21mm of back focus.

The main body of the UFD has a width of 20mm.

We include a thread adapter/extender that adds 1mm of back focus and adapts the tread from M54 (F) to M48 (F).

What's in the Box?

  • 20mm wide body of the filter drawer with M54 (F) threads on both sides
  • Aluminum drawer for 2-inch mounted filters with M48 (F) thread
  • 1mm extender with M54 (M) and M48 (F) - used to increase the total width of the filter drawer
  • Thread adapter M54 (M) and M48 (F)
  • Multiple screws
  • Two Allen keys

These parts require a high degree of dimensional accuracy to ensure proper fit, prevent light leaks, and allow filters to screw in as expected. Achieving such accuracy through 3D printing can be challenging, especially if your printer is out of calibration or if the filament shrinks or expands as it cools.

3D Printing Recommendations

Calibrate: Before printing the full models, print a test cube of known dimensions and measure it with a caliper. Use this test to determine any necessary adjustments for dimensional accuracy. Many calibration figures and test cube models are available online. Once you know how much your prints shrink or expand, use your slicing software to apply the corresponding correction to each axis.

If using commercial 3D Printing Services: Before ordering prints, inquire about their processes for ensuring dimensional accuracy.