Long Exposure Noise reduction
Does long exposure NR make that much of a difference?
This week I’ll be looking at the results of using the long exposure noise reduction.
A lot of cameras nowadays have a function called long exposure noise reduction. I always have it turned off as it takes the same time as the exposure to process the image, which is really annoying especially when you’re shooting with longer exposures.
I’ve been wondering what this function actually does so I’m going to go for a walk around the marina here in Dubai this evening and test it, to see if it really worth the wait. It’s in now way a scientific test or at the levels of DXO testing, just me and my camera shooting from a bridge into a bay of lights.
I’ll shoot a series of different shots with different settings, with and without NR on. As it is to do with noise, I’ll shoot different ISO’s (as that is the main setting that increases the noise) and I’ll shoot through the shutter speeds………..so I’ll probably need my ND filter and tripod.
If I shoot up to 20 second exposures, it doesn’t make a difference, so astro shots on the 50mm, 25mm, 24mm are ok….as I like to keep them under 20 seconds to avoid the stars streaking in these focal lengths.
On the 14mm I sometimes take it up to 30 seconds and from these shots you can see these multicoloured worm like bits start to appear….now where I am its 30 degrees and humid so this might be affecting the sensor, but If I use Long Exposure NR it does this……
It really does make a difference, not so much to the usual noise patterns you’d get with high ISO, but with these hot pixels that seem to get worse when the camera heats up, especially when you take really long exposures of say 4-8 minutes. Now you can either turn on the long exposure noise reduction option in camera and wait….this wouldn’t be viable if you were stacking shots to get say star trails as you’d get gaps in the trails, so this would mean editing the shot in photoshop.
If you are taking really long exposures and bumping up the shadows you’ll see a big difference, but anything faster than 30 seconds doesn’t really need long exposure noise reduction unless you are in a really hot country.
The heat seems to increase this noise so it would be interesting to try this test in colder environments.
It takes as long as the shot takes for this to happen, so this halves the amount of time you can shoot…..therefore I’ll be keeping NR in camera off and then dealing with it afterwards in the computer.