Black-and-White Photography Filters with Panchromatic Film.
Filter Filter
Factor
f/stop
Increase
Filter Effects Lightens Darkens
Medium 
Yellow 8
(K2)
2x +1 Renders grey tones as the unaided eye perceives them. Accurate tone range. Compensating for the blue sensitivity of panchromatic films.  Increase contrast between blue sky and clouds.  Also may help reduce haze. Yellow, Yellow-Greens, Pink, Orange.
Blue, Violet, Purple, Lilacs. SKIES, OCEANS, LAKES, RIVERS.
Deep Yellow 15
(O)
2.5x +1-1/3  Stronger effect than medium yellow. 
Yellow, Yellow-Greens, Red, Pink, Orange.
Blue, Violet, Purple. SKIES, OCEANS, LAKES, RIVERS.
Red 25
(A)
8x +3 Produces very dramatic skies.  Creates infrared-like surreal effects.  Reduces haze. Reds, pinks, magentas, some browns, yellow, orange Blues, greens, cyan. FOLIAGE, GRASS, ROSE STEMS.
Green 58
8x
+3
Lightens foliage and will darken skies somewhat.  May produces pleasing skin tones for portraits. Yellow, yellow-green, olive, greens. FOLIAGE. Blue, violet, magenta, red, maroon. CREATES SUN-TAN EFFECT WITH LIGHT COMPLEXION SKIN TONES. DEEPENS RED LIPS. BRUNETTE OR RED HAIR.
Green 11 4x +2  Lightens foliage and will darken skies somewhat.  May produces pleasing skin tones for portraits. Yellow, yellow-green, olive, greens. FOLIAGE.
Blue, violet, magenta, red, maroon. LIGHT-COMPLEXION SKIN TONES. LIPS. BRUNETTE OR RED HAIR.
UV 1x Absorbs UV radiation. Reduces distant haze or fogginess.

Polarizer 2.5x +1-1/3  Removes reflections and glare.  May cut pollution haze. Increases contrast of certain subjects somewhat.

SKIES, WATER.
Graduated Neutral Density
Varies, expose as if 1
Varies, expose as if 0
Reduces exposure for only part of the photograph.
One portion of the photograph, usually the sky, grass, beach, or foreground expanse.