Unverified85% confidenceFactTime unknown
焦外光斑（bokeh）质感由光圈叶片数和形状决定：9片以上圆形光圈能保持全开到收缩后光斑接近圆形；廉价镜头收到f/2.8后光斑变多边形，拍点光源背景（如夜景霓虹）差异明显
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85%
Confidence
Long-term
Relevance
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Unverified棱镜类型看BAK4优于BK7：将望远镜对准亮处观察出瞳圆斑，BAK4呈完整圆形亮斑，BK7边缘有灰暗方形切角，影响边缘成像和亮度75% similarUnverified全开光圈f/1.8时边缘画质较软、有明显口径蚀和暗角，需收到f/2.8左右画面整体锐度才显著提升73% similarUnverified镜头膜越厚保护越强但离镜片越远，边缘易在广角/超广角画面产生暗角和杂光；追求画质应选0.15-0.2mm超薄贴合镜片型，追求防摔选带凸起金属边框型71% similarUnverified全开光圈时中心锐度可用但边缘画质松散，收缩到f/4-f/5.6后画质明显改善；追求全开边缘画质的需求应考虑更高规格镜头71% similarUnverified双凸单片镜片在放大倍数超过5x时边缘畸变明显（枕形/桶形失真），需要高清晰度选非球面或双胶合消色差镜片，避免边缘图像模糊变色71% similar
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