FLI Precision Digital Focuser (PDF)

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FLI Precision Digital Focuser (PDF)
Item # FL-PDF
1 Questions(s)

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  • The Finger Lakes Instrumentation Precision Digital Focuser has 85mm aperture.
  • Specifically designed for modern CCD astronomy.
  • The thin design of the FLI Precision Digital Focuser allows focusing with short-travel optical designs.
  • ASCOM compliant and are supplied with a trial version of FocusAide.
  • Optional adapters available to attach the Finger Lakes PDF to STL, 2" SC threads, and more.


85mm Aperture FLI Precision Digital Focuser (PDF)

Low profile, accurate, repeatable and rock solid!

FLI's Precision Digital Focuser (PDF) is specifically designed for modern CCD astronomy where the digital imaging system is mounted very close to correct focus. The thin design allows focusing with short-travel optical designs. The PDF is ASCOM compliant and comes supplied with a special FLI version of FocusAide.

Based on FLI's highly successful DF-2 design, the PDF is larger, stronger, includes an internal temperature sensor and is controlled with an extensive software package, FocusAide. The PDF avoids vignetting even when used with the largest CCD sensors and medium format film. It is designed for CCD astronomy & microscopy, and the PDF's thin design allows it to be used with nearly any optical instrument.


Three heavy duty lead screws set the distance between two parallel plates. Each plate of the PDF is bored and threaded to receive camera and mounting adapters (sold separately). The three lead screws are driven simultaneously, thus moving the plates closer or further apart in a very accurate manner. Light shields are included along with a motor mount, cover, and electrical connections. The closely fitted pins and journals prevent rotation or lateral shift between the plates. Finally, three stages of reduction are employed for high mechanical advantage and extreme resolution. Other critical elements incorporated into FLI's design include rotational symmetry to enhance stability and strict attention to kinematics. Accurate machining is employed, using CNC equipment to achieve consistent, ultra smooth operating characteristics. Precision grade components ensure that lead screws turn exactly in phase. Each integral PDF component is specified for the lowest possible wear and minimal maintenance under extreme environmental conditions.

Large Aperture Computer Controlled Focuser with Backlash Compensation

  • FocusAide software package included with PDF
  • 3.45" Clear Aperture!
  • USB interface
  • 0.0001"/Step Resolution
  • 0.40" Travel
  • Front and rear threads are 3.75 inch -24, making the PDF adaptable to virtually any camera and telescope combination
  • A.
  • Weight is 3 lbs.
  • Sky Blue anodized
  • Power requirement is 12 VDC @ 1 A
FLI Product Number: PDF
Additional Information

Additional Information

Manufacturer FLI
Focuser or Mask Size 2" Drawtube
Focus Control Digital
Warranty 1 Year Warranty
Included Items

Included Items

  • FLI 85mm Aperture Precision Digital Focuser (PDF)
  • FocusAide Software Trial Version
  • USB Cable
Questions & Answers

Product Questions

Will this fit on an 8" Edge HD or will the knobs on the back of the scope interfere with the focuser?
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