What is a BSI sensor and are they actually important? BSI sensors explained

Sony BSI sensor diagram
Back illuminated sensors effectively reverse the photo-diode and wiring layers so that the wiring doesn't get in the way of the light coming in. (Image credit: Sony)

BSI, or Back Side Illuminated sensors are also known as ‘Back Illuminated' sensors. They are a revision of traditional sensor designs which increases the light gathering efficiency of the sensor to deliver higher sensitivity, less noise and better all round image quality.

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Rod Lawton
Contributor

Rod is an independent photography journalist and editor, and a long-standing Digital Camera World contributor, having previously worked as DCW's Group Reviews editor. Before that he has been technique editor on N-Photo, Head of Testing for the photography division and Camera Channel editor on TechRadar, as well as contributing to many other publications. He has been writing about photography technique, photo editing and digital cameras since they first appeared, and before that began his career writing about film photography. He has used and reviewed practically every interchangeable lens camera launched in the past 20 years, from entry-level DSLRs to medium format cameras, together with lenses, tripods, gimbals, light meters, camera bags and more. Rod has his own camera gear blog at fotovolo.com but also writes about photo-editing applications and techniques at lifeafterphotoshop.com