Deep yellow (#15) filters are useful when observing Mars, especially to highlight bright areas or darken brown or blue features.
It may increase contrast when observing Mercury.
When observing Jupiter, #15 can be used to darken blue festoons near the equatorial regions.
For observing Uranus or Neptune, the #15 filter enhances the blues and greens of the atmosphere.
1 1/4" Vernonscope Mounted Glass Filters feature 1" clear-aperture optical glass. Numbers are engraved on the mounting to correspond with those of Kodak Wratten series. The mountings are edge-knurled and threaded to fit the bases of BRANDON oculars and DAKIN Barlows. Vernonscope Mounted Glass Filters cut glare, provide superior contrast, improve definition and reduce eye fatigue.