* Astronomy

Members Login
    Remember Me  
Post Info TOPIC: Minus Violet Filter


Posts: 131433
Minus Violet Filter

Minus Violet Filters are used primarily to eliminating blue halos around bright stars in colour photography using refracting telescopes.   They will to a lesser extent reduce visual chromatic aberration in achromatic refractors, (though a yellow filter will probably be better).  The filter transmits 90% of the Green and Red while selectively reducing about 50% of the blue.
The Minus Violet Filters can be used as "visible" filters in RGBV (red-green-blue-visible) astrophotography with reflecting telescopes.
The Minus Violet filter blocks wavelengths shorter than about 420nm (Infrared filter blocks wavelengths shorter than about 400nm and all wavelengths longer than 750nm).
The 1.25" Minus Violet Filter threads into the barrel of standard 1.25" eyepieces.

Read more 

UV Transmission x-ray to 350nm <.1%
Blue Transmission approximately 50%,
Green and Red transmission approximately 90%
IR Transmission 750nm to 1050nm <.1%

Comparing Minus Violet filters to #58 wratten for Mitigation of Chromatic effects in Achromats; Double Stars

Read more 

Ed ~ As an update, these filters have become somewhat redundant with the introduction of the new (and improved) Semi-Apo, Contrast Booster and Fringe Killer filters.

Page 1 of 1  sorted by
Quick Reply

Please log in to post quick replies.

Create your own FREE Forum
Report Abuse
Powered by ActiveBoard