By direction
从光的方向分：前光，也有叫正光，就是光照在被摄物上，可以用来表现被摄物的纹理。测光，会产生被摄物的影子，可以用来表达景深。
后光，或叫逆光，表达被摄物的形状。
顶光，这些都没有，太平。所以中午，尤其是夏天的中午（太强，纹理就没了）不是照相的好时候。
front
top
side
back
By Quality
normal
有方向，也有强度。
hard一般指中午的阳光。一定要有取舍。
diffuse
漫反射光，看不出方向，有一定强度。拍摄细节，
heavy overcast
大阴天，与diffuse差不多。只是强度不够。用三角架就好。
如果不是想表现蓝天白云，后两种情况是比较好的拍摄环境。
By Time
dawn and twilight:
Morning light:
- It is the best time for garden shooting since the color of the flowers is accurate at this moment. Using aperture f/10 with shutter 1/100 to record full details.
- Good time for harbor;
- Interest in human shade;
Afternoon light:
- get warmer and softer;
- using small aperture to gain the depth of field;
- it is time for landscape shooting;
midday:
- worst time to shoot;
- Need consider: deep black shades, contrast situations
- Good to high contrast and some painted surface
golden hour :
- BEST time to shoot
- one hour just before of late the sunrise
- color is getting warmer.
Sunrise and Sunset
- sunrise is more pink and sunset is more orange
- Meter away from the sun, somehow under espouse
- Hide the sun from your frame
- Shoot in raw
- Come early and stay late
- try other side instead of The SUN