Beginner High-ISO noise reduction (in-camera)

[RacingSnake]

Adding this as beginner, because we're all still learning

I've always since day 1 with my 450, and now with my 7D had this switched on.
Just how good is this?

Do I lose IQ by having it enabled? would I be better off disabling this and managing any noise in post?

 

[Chunkey Monkey]

I take your shooing Jpeg, I use a 60D and 7D and remove as much noise as I can in post processing as I only shoot RAW

 

[Oj9400]

When you have it enabled it takes the exposure, then takes another with the shutter closed and removes the noise it sees from the first image hence why it takes twice as long to take the image as the shutter time set. Its not different to taking some dark shots when you finish like some people do and then removing in post. Im not sure which it best, when shooting night timelapse I need a short period between shots so I disable and then take dark shots to remove noise afterwards. Someone may know which is best. Removing by using denoise in PS or LR is more colour association with nearby pixels and softens the image quite a lot.

 

[Chunkey Monkey]

I'm 99% sure in RAW the built in noise reduction doesn't apply ( will check) As the 7D is primarily for action shots I wouldn't want to miss any action due to using built in noise reduction, If you have loads of time then use lower ISO and maybe tripod.

Edit::: Just tried a few scenarios and the noise reduction doesn't apply with RAW so it only works when you use Jpeg. Now as far as I know it is harder to change post processing in Jpeg than RAW I would suggest if you know how to process shoot Raw where you will have far more control over the processing and the noise.

I am pretty sure it will have an effect on image quality in jpegs.

I'm sure some one with more experience will come along and explain better.

 

[StewartR]

When you have it enabled it takes the exposure, then takes another with the shutter closed and removes the noise it sees from the first image hence why it takes twice as long to take the image as the shutter time set.

What you've described is Long Exposure Noise Reduction, not High ISO Noise Reduction.