RAW and LENR

MWHCVT

MWHCVT

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Matthew
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I got to thinking today after seeing a question posted on Facebook though not this question I hasten to add, now personally I don't use LENR and I never have because generally my shooting style isn't conducive to using it, as its no good at all for star trails, light trails I need to have fully control over when I start and stop exposures, likewise with fireworks, and sunrise/sunsets are such a fast moving situation that I personally want to waste as little time as possible to get as much as possible out of a shooting session so about the only time it would be of use would be light painting and even then only on a limited basis...

Anyway to the question...if you shoot in RAW is there actually any reason to use Long Exposure Noise Reduction as would it actually be applied to a RAW file? The reason I say this is any other in camera processing will not actually apply to a RAW file, for example if you shoot RAW even if your set the camera to B&W the raw file will still come out in colour...


Thoughts appreciated

Matt
 
I think LENR is perhaps not quite the term I would use for the function which really is a hot pixel map. It compares what should be a totally black frame with the original frame and then removes any output seen on the black frame from the corresponding position on the original.
Noise?...yes, I suppose so but not in the way we normally perceive it.

Bob
 
Canon Bob said:
I think LENR is perhaps not quite the term I would use for the function which really is a hot pixel map. It compares what should be a totally black frame with the original frame and then removes any output seen on the black frame from the corresponding position on the original.
Noise?...yes, I suppose so but not in the way we normally perceive it.

Bob
Click to expand...

I always assumed it was more about hot pixels than noise, however it still makes me wonder as since its effectivly a form of in camera processing will it actually alter the RAW file?

Cheers for confirming however that it's more to do with defective pixels than noise :thumbs:
 
Crank up the Iso to maximum and then pop of a 20-30 second exposure and see whether the noise has been cleaned up....I suspect not.

Bob
 
Canon Bob said:
Crank up the Iso to maximum and then pop of a 20-30 second exposure and see whether the noise has been cleaned up....I suspect not.

Bob
Click to expand...

I think this is going to be the answer, I'm going to have to do a test exposure tonight :thumbs:
 
T'will be interesting to see what happens Matthew.....most if not all my stuff is sub-1 sec so it's not something that I've used.

Bob
 
Canon Bob said:
T'will be interesting to see what happens Matthew.....most if not all my stuff is sub-1 sec so it's not something that I've used.

Bob
Click to expand...

Indeed it shall be interesting as I'd say my average exposure is about 30 seconds, but as I've said in the opening post while I see little application for it in what and how I shoot, I'm interested to know how it will affect the image, especially when shooting RAW
 
Nikon's description of LENR is:

"Long-exposure noise reduction reduces noise (bright spots, randomly-spaced bright pixels, and fog) in photographs taken at slow shutter speeds."

Link.
 
Ozei said:
Nikon's description of LENR is:

"Long-exposure noise reduction reduces noise (bright spots, randomly-spaced bright pixels, and fog) in photographs taken at slow shutter speeds."

Link.
Click to expand...

I'm intrigued as to what Nikon mean by "fog" :thinking:
 
I've just done a few tests Matthew and the results seem to imply that the sensor data isn't changed but processing data is added to the file.

I shot a 20 second exposure at high Iso with the body cap on and LENR off and then repeated it with LENR on. If the hot pixels had been eliminated from the Raw data then I would expect the second file to be smaller if anything but it was considerably larger (+3Mb).

Bob
 
I was shooting the Milky Way at Buttermere at 2AM-3AM on Saturday morning. 5D3 and various ISO upto 5000 with exposures of upto 30 secs. Surprised myself how little noise there was.
Surprisingly there was some noise showing where I picked up the light pollution from Whitehaven/Workington, but that was easily removed with a brush in LR.
 
Ozei said:
Apparently fog = leakage.

I just googled it so I have no idea whether this means light leakage, electronic leakage or something else.
Click to expand...

Very interesting as I'm not sure how it could deal with true light leaks however I'm guessing it could deal with where a sensor is starting to over heat in theory that has caused a aberration

Canon Bob said:
I've just done a few tests Matthew and the results seem to imply that the sensor data isn't changed but processing data is added to the file.

I shot a 20 second exposure at high Iso with the body cap on and LENR off and then repeated it with LENR on. If the hot pixels had been eliminated from the Raw data then I would expect the second file to be smaller if anything but it was considerably larger (+3Mb).

Bob
Click to expand...

Interesting, I'm ashamed to say it didn't even occur to me to do a lens cap on long exposure sat here waiting for night time :lol: :bang:
 
MWHCVT said:
Very interesting as I'm not sure how it could deal with true light leaks however I'm guessing it could deal with where a sensor is starting to over heat in theory that has caused a aberration
Click to expand...

Yes, I'd say it means an electronic leakage between adjacent photosites - caused by the sensor heating up during a long exposure.
 
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