Question: what do the colored rings on canon lenses mean
[{'answer': "to identify Canon 's lenses", 'provenance': [{'wikipedia_id': '5900855', 'title': 'Canon L lens', 'start_paragraph_id': 4, 'start_character': 245, 'end_paragraph_id': 4, 'end_character': 273, 'bleu_score': 1.0, 'section': 'Section::::Characteristics.\n'}]}, {'answer': 'to reduce heat absorption under the sun that may otherwise affect the performance of the lens'}, {'provenance': [{'wikipedia_id': '5900855', 'title': 'Canon L lens', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 765, 'bleu_score': 0.863838585812813, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14106941670285971596}, 'section': 'Section::::Characteristics.\n'}]}]