3
the VFF to add 11mm of length. Start at the 55mm mark on the millimeter scale
and rotate the housing to the 66mm mark. Then turn the locking thumbscrew
clockwise until it’s tight. You’re done! No extension rings needed. And if needed
you can make fine adjustments to the VFF’s length to “dial in” the perfect backfo-
cus without removing the camera or filter wheel.
care & Maintenance
Care should be exercised when using all optical and mechanical telescope
accessories. Keep your VFF in a protected environment when you’re not using
it, and place the dust cap and threaded metal cap on the VFF for storage. Avoid
touching the lenses and coatings. If the outside of the lens should become dirty,
you may want to clean it. Blow off all loose dirt with a blower bulb. Use only opti-
cal lens tissue and good-quality lens fluid. Wet a folded tissue and gently wipe
the surface of the lens. Immediately use a second piece of lens tissue to gently
dry the lens off. Do not rub or apply pressure, as this may scratch the lens if dust
or grit is present.
specifications
Optics
2-element, fully-multicoated
Focal Length
55mm (backfocus)
Adjustability
55mm – 80mm
Compatibility
Refractors of 400-660mm focal length (f/5 to f/6)
Camera-side mounting Interchangeable thread-on plates:
42mm (42x0.75) male “T”-threads
48mm (48x0.75) male threads
Filter threads
Threaded for 2" imaging filters
Clear Aperture
50mm
Barrel:
2", tapered neck
Weight
12 oz. (340g)
