Canon 5DMk3 and in camera noise reduction when shooting RAW

What are your recommendations for use of in camera noise reduction on the 5DMk3 when shooting RAW?

Shoot 3/ Long exp. noise reduction: -Disable, – Auto, - Enable

Shoot 3/ High ISO speed NR: - Standard, - Low, - High, - Disable


With my 5DMk2 I have turned off ‘High ISO speed NR’ the reason being that I believe post processing NR will give you more control and in some cases produce a better final result than the algorithm used in the camera.

But I have had the ‘Long exp. noise reduction’ active. As I understand it, this is a more ‘hardware related’ noise reduction. The camera takes one ‘black’ image with the same duration as the shutter speed (without opening the shutter) as of the first image and then ‘subtract’ the ‘dark noise’ to cancel out noise related to how the sensor response to the temp. etc. Is this a correct assumption?

High ISO NR does not affect RAW.

And yes Long exposure NR is performed by hardware and affects RAW files. It should be set to auto for 5D3 so it's only activated when needed.