Me and my gang have a short discussion last week whether should  we use the camera Long exposures noise reduction (NR) or not … as it normally produce hot pixel (red dots) after the long exposures shot especially involve a lot of dark area (black, dark grey ….). e.g. show below

Red dots appear … without the Long Exposure (LE) NR turn on camera body

But from my experience the noises and even the red dot can be reduce manually in Adobe Camera Raw (ACR) noise reduction function …

here are few pictures capture

1. with LE NR turn on

2. no LE NR turn and no PP

2. no LE NR turn and with ACR NR

simple ACR Noise Reduction

a 100% crop of 3 pictures above

*** all the setting are the same and it look slight different due to the sky turning dark …

Canon 5dm2 + Canon 1635L

# Exposure Time (1 / Shutter Speed) = 79/1 second ===> 79 second
# Lens F-Number / F-Stop = 11/1 ===> ƒ/11
# ISO Speed Ratings = 200

based on the 3 pictures compare

– picture with LE NR turn on body require double exposure time
– less noise especially the “red dot”/hot pixel
– the one without any NR with more details
– simple NR on non LE NR picture can reduce more noise and all red-dot (hot pixel) disappear. Even less details compare to the LE NR turn on picture. But this sure can be fine tune by some masking the foreground or main object

So if you ask me, is it worth to spend double the time while shooting ? my answer is no while I can reduce the noise in PP … so I will safe more time to shoot and remove the noise later …..