Amongst a lot of the online photography communities I am privileged to be a member of, I have noticed a lot of confusion lately regarding noise in photographs, specifically in relation to exposing correctly – I have seen many people saying that as long as you expose correctly, irrespective of ISO settings, you will get no noise/grain in your images.
(disclaimer: I am by no means any expert, nor do I claim to be. My opinion is given based on my own observations and experience)
Before I give you my opinion on noise caused by ISO settings, I will give you a brief explanation of ISO as I understand it.
Within your exposure triangle (shutter speed, aperture, ISO), your ISO determines your camera sensor’s sensitivity to available light.
Lower ISO = less sensitivity to light = less noise
Higher ISO = more sensitivity to light = more noise
In order to retain image quality and detail in your image, you should attempt to keep your ISO as low as possible based on your lighting conditions.
Of course, low ISO isn’t the only culprit of creating noisy images. Underexposure also creates noise. It is imperative to understand that in low light situations, there are no solutions to having a noise free images – you will have to compromise somewhere along the way. In order to use a low ISO, you require light to achieve a correct exposure.
Not taking underexposure into consideration, what I want to show you today is the amount of noise generated by the various ISO’s when achieving the correct exposure.
All the below images were taken with my Canon 50mm 1.8, outside using natural light (open shade). I kept my aperture at 2.8 and adjusted my shutter speed each time as I increased my ISO to keep my exposure hovering around +1 (ETTR).
And a comparison of all the 100% crops showing the detail and noise.
By no means is grain completely undesirable. Often it can ‘make’ a photograph – many photographers shoot intentionally at high ISO’s to achieve grain in their images. Others add it in post production.
Some amazing artists who I have seen use intentional grain in their images and incorporate it as part of their style, are Anders Petersen, Erin Watson and Keizo Kitajima.
In closing – even if you are exposing correctly, high ISO’s will still result in noisy/grainy images. I hope the above examples have shown you exactly that.
If you feel my observations are incorrect or you would like to point something out (or even say thanks! ) feel free to leave a comment below or drop me a mail.
Thanks for looking, and chat soon!