Sirius Optics Variable Filter System (VFS) 1.25 NEW IN BOX $135

This is a new VFS filter system that I never used. It was stored indoors, sealed, in a smoke free environment, so I can't comment regarding a review. I only know it was $300 and I never got around to trying it out although I did once meet the Sirius company owner by hazard at NEAF;-)

Shipping is $19 for first class (5 days according to USPS). I found a Meade 3x telenegative multi-coated Barlow inside but don't recall buying that, so I assume it must have come with the filter system. Also, I don't know what happened to any literature if there was any within the box.

The Variable Filter System, or VFS, is a unique form of interference filter. The filter's glass has coatings deposited on one side of its surface and is unlike died colored glass absorption filters. This method of filtration rejects most incoming light while allowing a very high transmission of light through three thin bandwidths or peaks to come through the eyepiece. What makes it unique is that all three bandwidths are "variable" and move in unison.

The VFS also has a broadband hydrogen alpha range where the eyepiece image shows stars and planets as a deep red. This range can also accentuate different details in emission nebula.

THE VFS IS COMPOSED OF A 71mm DIAMETER INTERFERENCE FILTER IN AN ALUMINUM HOUSING. THE EXPOSED WHEEL PERMITS ADJUSTMENTS.

THE FILTER SCAN SHOWS 3 HIGH TRANSMISSION PEAKS THAT CAN VARY UP TO 200nm.
THERE IS STRONG REJECTION BETWEEN THESE PEAKS.

VARIOUS OBJECTS WILL RESPOND DIFFERENTLY ACCORDING TO THEIR SPECTRAL OUTPUT (COLOR CONTENT). JUPITER AND MARS WILL REPOND MORE DRAMATICALLY THAN A PLANET SUCH AS SATURN. GOOD SEEING CONDITIONS ARE A STRONG PLUS TO WHAT IS SEEN THROUGH THE FILTER. TURN THE WHEEL SLOWLY AS EXTRA DETAIL MAY APPEAR SUDDENLY. CERTAIN POSITIONS WILL ENHANCE MANY NEBULAR OBJECTS. THERE IS MUCH EXPERIMENTATION TO BE DONE ON VARIOUS OBJECTS.

MODERATE TO HIGH MAGNIFICATION IS NEEDED TO SEE MUCH OF THE SMALLER DETAIL THAT MAY BE ENHANCED. IF THERE IS DIFFICULTY ACHIEVING FOCUS, THE ADDITION OF A SHORT BARLOW ATTACHED TO THE FOCUSER WILL SOLVE THIS PROBLEM. WITH REFRACTORS, REMOVING THE DIAGONAL WILL ALSO SOLVE THE FOCUSSING DIFFICULTY.

TO AVOID MOISTURE FORMING ON THE FILTER, REPLACE THE CAPS BEFORE TAKING THE FILTER IN FROM A COOL NIGHT.