Why is my ISO 100 image noisy?

Why is my ISO 100 image noisy? The short answer is because of underexposure.

If you meter off of a brighter area in a scene, your photo will be darker. You can increase the exposure of dark photos in Lightroom, but doing so will add noise to your photo.

If you increase the exposure in Lightroom, you will get a noisier image as if you had used a higher ISO when taking the photograph. The same goes for if you are trying to lighten shadowy areas of an underexposed image.

Let’s explore why noise appears in digital photos and what you can do about it.

What is noise?

In digital photography, noise is random flickering pixels that appear as small specks of color on your photo. It’s important to note that noise and grain are not the same things. Grain is the traditional film equivalent of noise, and it’s an inherent quality of the medium. Noise, on the other hand, is a by-product of digital image capture and can be minimized through proper camera settings and/or post-processing.

Why does noise appear at high ISOs?

All digital cameras have what’s known as an image sensor. This sensor is responsible for capturing the light that comes through the lens and translating it into an electrical signal. The job of the image sensor is made more difficult when shooting in low light because there’s simply less light to work with. As a result, the camera has to amplify the signal from the sensor, which inevitably introduces noise into the final image. That’s why you’ll often see more noise in photos taken at night or in dimly lit rooms than you will in photos taken in bright sunlight.

How to reduce noise in your images

Now that we know what noise is and why it appears in photos, let’s take a look at some ways to reduce it. Perhaps the simplest solution is to shoot at a lower ISO setting. If your camera has an ISO range of 100-12,800, for example, try setting it to ISO 400 or 800 instead of ISO 3200 or 6400. By shooting at a lower ISO, you’re giving your camera’s image sensor less work to do, which means there’s less opportunity for noise to creep into your photo. Of course, this solution isn’t always possible if you’re shooting in low light because doing so will require either a slower shutter speed (which can lead to blur) or a wider aperture (which can reduce depth of field). 

Another way to reduce noise in your photos is through post-processing. If you shoot in RAW format (which we highly recommend), you’ll have much more control over how your photo looks during editing than if you shoot in JPEG format. In most editing software programs, there will be specific tools for dealing with noise reduction. Be careful not to go overboard with these tools, though, as they can quickly turn your photo from looking natural to looking fake if used excessively. A little bit of noise reduction can go a long way!

Conclusion

Noise is an unfortunate reality of digital photography, but that doesn’t mean you have to put up with it! By shooting at a lower ISO and/or using post-processing techniques judiciously, you can minimize or even eliminate noise from your photos altogether. And don’t forget — a little bit of noise can actually give your photo character and make it look more natural than if it were perfectly smooth! For me personally, I love adding a bit of noise in my portrait photography to add a little character to my images, but it’s a personal preference.