- Software Bisque
- PlaneWave Instruments
- Starlight Instruments
- APM Telescopes
- Baader Planetarium
- QSI - Quantum Scientific Imaging, Inc.
- RC Optical Systems
- Lunt Solar Systems
- Optec
- Lumicon
- Parallax Instruments
- Hutech
- Diffraction Limited (Maxim DL)
- TeleVue
- The Real "Craig's List" - OPT Rewards Program
- Warren Keller's IP4AP- Image Processing For Astrophotography
- Astronomik
- Sbig
- A Letter From OPT To Members