Setting the Record Straight on High ISO Noise Reduction

Canon includes a custom function in their EOS-1D Mark III, EOS-1Ds Mark III, EOS 40D and EOS Rebel XSi models called High ISO Noise Reduction, which is turned off by default. This is a great new feature in Canon digital SLR cameras IF you understand how it works and when it works.

Digital SLR Noise
When a digital SLR camera is used at higher ISO settings, it will tend to generate more noise in the images it produces than at lower ISO settings. This usually occurs at ISO setting such as 1600 or 3200. There are two types of noise generated, Luminance and Chrominance.

Here’s What’s Important
Canon’s High ISO Noise Reduction custom function only works on Chrominance noise and only on images that are processed “in camera” from RAW to JPEG. That’s right. ONLY on Chrominance noise and only on images processed “in camera”.

What About RAW files?
Since RAW files are “developed” off camera using a variety of software products, the Canon High ISO Noise Reduction setting has NO EFFECT WHATSOEVER! Having said that, Canon’s RAW Image Task software will read the CR2 file and if the High ISO Noise Reduction function was enabled it will apply chrominance noise reduction similar to what the DIGIC III processor does. The High ISO Noise Reduction custom function will have NO EFFECT WHATSOEVER on Canon’s Digital Photo Professional (DPP) software like any other RAW processing software such as Adobe Camera RAW or Lightroom.

Setting the Record Straight!
If you’re a wedding photographer or just someone that prefers JPEG files and shoots in low light conditions, this custom function can make a huge difference in the quality of your images. However, if you shoot RAW and perform your post-capture processing in Adobe Camera RAW or Lightroom, then leaving this function disabled makes much more sense! Especially since this custom function reduces the maximum burst rate significantly.

Straight from the Horse’s Mouth
Canon has published a great article on their High ISO Noise Reduction custom function that goes into great detail about this often misunderstood setting. This article cuts through the marketing propaganda finally sets the record straight for RAW shooters like me.

All I can say is “It’s About Time!”

Canon 40D High ISO Noise Reduction

Every photographer wants his or her images to be as sharp and noise-free as possible. Software based noise reduction such as Noise Ninja or even the noise reduction settings in Adobe Lightroom 2 can help tremendously but preventing noise “in camera” makes all the difference in the world.

The Canon 40D includes a custom function for high ISO noise reduction which is enabled by selecting C.Fn II:Image -2 and setting it to 1 (On). According to Canon:

“The EOS 40D features a custom function for high ISO noise reduction. This can be used on images shot at high ISO speeds to help reduce the appearance of noise in the final image. If the custom function is turned on, some noise reduction will be applied at all speeds, but it will be most effective at higher ISO settings. If you do set high ISO noise speed reduction, you will notice that the burst rate is dramatically reduced due to the extra processing required in the camera. In the EOS 40D, the maximum burst will only be 8 shots regardless of the file size recorded.”

It's Lonely at the Top

It’s Lonely at the Top
Copyright © 2008 Jeff Lynch Photography
Shot taken with a Canon 40D , 70-200mm f/4L at 152mm, f/13, 1/400th sec at ISO 400 with C.Fn II-2 set to (1:On) on SanDisk digital film.