• Welcome to the Lightroom Queen Forums! We're a friendly bunch, so please feel free to register and join in the conversation. If you're not familiar with forums, you'll find step by step instructions on how to post your first thread under Help at the bottom of the page. You're also welcome to download our free Lightroom Quick Start eBooks and explore our other FAQ resources.
  • It's Lightroom update time again! As well as the usual new cameras, lens profiles and bug fixes, Lightroom Classic has a new local Hue tool, improved ISO-specific defaults, performance improvements and more. The Lightroom cloud ecosystem also gets local Hue, as well as Versions, Activity notifications, text watermarking and the ability to upload your own Discovery tutorials. Here are the full updates about Lightroom Classic and the Lightroom cloud ecosystem.

ISO mode on DSLRs


New Member
Dec 3, 2007
This might be a silly question but how does the typical DSLR sensor implement different ISO speeds? Does the sensor actually somehow change sensitivity or is it a simple matter of multiplying the sensor's recorded input values by the ratio of the current ISO speed to the base ISO speed (e.g. 4x when using 4'' on a camera that supports 1'' at its slowest)?

Brad Snyder

Senior Member
Nov 20, 2007
Port Deposit, Maryland USA
Lightroom Experience
Eric, start with the Wikipedia article here:


and then Google "Digital ISO".

There's some very technical stuff, some out of date stuff, some simplistic stuff. Fundamentally, I believe the answer is yes, increasing Digital ISO is an electronic/mathematical manipulation of the photon count the sensor saw.