Along with aperture and shutter speed, ISO is one of the three fundamental parameters that control the balance of exposure in your images, and as such, mastering it is crucial to becoming a competent and confident photographer. If you are new to photography and looking to improve, check out this great video tutorial that will give you a practical guide to ISO and how to use it in your work.
Coming to you from Park Cameras, this excellent video tutorial will show you the ins and outs of ISO and how it affects exposure. By far, the biggest mistake I see new photographers make with regards to ISO is keeping it too low to allow a fast enough shutter speed to mitigate camera shake or capture the action at hand. This is done in an attempt to keep noise at bay and increase image quality. It is important to remember, however, that while modern software can do quite a lot to reduce noise in an image, if an image is blurry due to camera shake or subject motion, there generally is not much that can be done to save it. So, don't be afraid to raise that ISO to keep your shutter speed where it needs to be. Check out the video above for the full rundown.
Come on fstoppers, surely you can do better than this.
First of, it is not I.S.O it is one word....ISO.
Secondly, you ran an excellent video about a week or so ago educating readers that ISO is not about increasing sensitivity but rather how the camera processor interprets information from the sensor, (see link below). Please, review your articles for consistency, otherwise you are simply a clearing house for every photographic theory out there.
https://fstoppers.com/post-production/how-get-clean-photos-when-shooting...
ISO has nothing to do with a sensors sensitivity to light. Its a boost in gain of the signal received at the sensor or in simpler terms a digital boost in the image brightness.
And then the classic comparison of comparing ISO 400 to ISO 10,000 and claming that the ISO 10,000 image is noisier because a higher ISO was used is wrong. The image is noisier because a quicker shutter speed was used to maintain the same exposure value as the other image. The quicker shutter speed means less light was captured in the higher ISO image, which then results in a lower signal-to-noise ratio and thus the noise is more visible. Repeat the ISO 400 and ISO 10,000 test again without changing shutter speed or aperture and you will see that ISO typically doesn't affect the amount of noise in image (except for ISO variant cameras, in which case the higher ISO image will have less noise).