Shèyǐngshī zài jìngtóu qián jiā le yí gè lǜsèjìng.
The photographer attached a color filter in front of the lens.
Tips
memory
滤 (filter) + 色 (color) + 镜 (lens/glass) - the meaning falls right out of the parts. Pinyin tip: 滤 is lǜ with the ü vowel (rounded i), not lu - same vowel as 绿 (green).
