5D2 Shoots RAW: Should "Long Exposure Noise Reduction" On or Off?

Hi All,

I notice that my 5D2 may needs to take about half minute to save the RAW file with 30 seconds long exposure.

On Flickr, there were some discussion about this topic:

Long Exposure noise reduction feature on 5D Mkll

Kinematic Digit ** says:
I can't remember for certain, but I believe Long Exposure Noise reduction actually affects RAW files. One of the two options does not and only affects JPG files. LENR uses two exposures. The extra frame is a dark frame reduction which shoots an exposure for the same length of time as the original exposure with the shutter closed, then does a comparison of the noise and removes it. It's not the same as regular noise reduction which is based on an averaging algorithm.

Just verified it from Chuck Westfall of Canon in this article:
digitaljournalist.org/​issue0912/tech-tips.html

Q: The data from turning on High ISO noise reduction isn't used by third party software like Lightroom, but what about Long Exposure NR? Does the long exposure noise reduction change the actual pixel data in the RAW file or is it separate data that isn't used by Lightroom?

A: Long exposure noise reduction applies to RAW data as well as in-camera JPEGs. Adobe software such as Lightroom and ACR (Adobe Camera RAW) will "see" it because it's already in the image data before RAW conversion.

My questions are:
Can DPP, or LR3/CS5 do better job than the 5D2 in camera "pre-RAW" process?
I'm better off to turn Long Exposure noise reduction feature off or not?

Many thanks...

? No one have any though

I might have to find out myself then...

Merry Xmas 7 Happy New Year

The camera uses a "dark frame subtraction" method for Long Exposure NR -- it takes a "shot" with the shutter closed that is equal to the time of your long exposure, then calculates the image noise in the dark frame and removes it from your exposure.

Whether you would benefit from turning it on in the camera or not is, well, up to you. I've never turned it on and been fine with the relatively few long exposures I do, but that's me. Maybe run some tests with it on and off for a particular scene and see?

Thank Tony,

Seem to me just it's bit crazy for pre-RAW in camera adjustment - which I only notice few weeks back. And I turn it off last week anyway.

But I have to test for my self before I go for holiday trip this weekend.

That would probably be wise to test ahead of time!

I'd say if one was shooting jpegs, it helps to turn on your various camera features because the camera is performing these things on the Raw data before creating the jpegs. But for Raw shooters I tend to prefer even the long exposure NR to be off.

I believe, and i might be wrong, BUT, i think LTNR only affects JPEG format. I dont think it has any affect on raw files.

Check this related thread:

https://photography-on-the.net …/showthread.php​?t=1127603

Chuck Westfall is quoted as saying (what I've always thought) that Long Exposure NR is applied to the Raw data.

I can't say the same holds true with the 5D II, but with my 5D it seems to remove any stuck or hot pixels and generally seems to provide less noise especially in the shadows.

Of course YMMV, it's worth testing.

-Tim

I did a test on the 7D and it helps to have it ON. I only tested at exposures over 30sec though. I'd suggest only have it on for 30s+ exposures or long exposures at iso200+, since noise is getting stronger. It takes longer, but I do the exposure and while it's taking the black frame I just grab the camera and go look for a new spot I shoot Raw

x_tan wrote in post #13566274
My questions are:
Can DPP, or LR3/CS5 do better job than the 5D2 in camera "pre-RAW" process?
I'm better off to turn Long Exposure noise reduction feature off or not?

Your software can detect a good bit of the hot pixels and noise that come from long exposures, but it can not do a better job than the in camera noise reduction feature.

You would be safe to leave that setting on "auto". The camera has a pretty good idea of when it is needed and when it is not. When set to auto, it will rarely need to use it for 30 second exposures.

Mark-B wrote in post #13572419
Your software can detect a good bit of the hot pixels and noise that come from long exposures, but it can not do a better job than the in camera noise reduction feature.

You would be safe to leave that setting on "auto". The camera has a pretty good idea of when it is needed and when it is not. When set to auto, it will rarely need to use it for 30 second exposures.

+1
It is the best type of NR since it only targets and affects the noise pixels, not the entire image. You could, of course, make a second black frame exposure yourself and treat those pixels in PS, but that's a PITA. Usually, any subject that has needed a 30 second exposure won't need another shot immediately after.

I normally don't do long exposures so for me, turning on the feature isn't useful.
When I do long exposures though, normally it's for astrophotography, so I need to have that feature off. Take as many pics you can while the skies are clear, and when it isn't, take a few dark frames and use a program (DSS) to stack everything when I'm done.

If you tend to take a lot of long exposures at night, maybe you can turn it on if you feel you don't need to take another picture right away.

Also, if you are taking a bunch of long exposures at the same shutter speed, then maybe you could just take one frame w/ the lens cap on or something and subtract it manually for all the pictures. I guess it's up to you if you want to take up time while shooting, or take up time during PP.

Oh, I have a 7D, not a 5DmkII, but i was talking about LENR in general.

Thanks everyone

Finally I can put up some shoots tonight.

135L @ f/2.2, ISO 100, Auto White Balance, Manual focus on the back of the rear wheel of the car on the left, 30 Seconds, Portrait mode.

Saving time: Off ~ 1 Second; Auto ~ 1 Second; On ~ 30 Seconds

I can't tell much different with those shoots. So, I keep my 5D2 off with this function for now At least I'll not turn it to 'On / C. Fn II 2' as it was pain to wait for 30'.

Click for full size uncrop jpg file. DPP convert; Everything set to Zero.

IMAGE LINK: http://www.flickr.com/​photos/x_tan/654315031​9/

IMAGE LINK: http://www.flickr.com/​photos/x_tan/654316242​7/

IMAGE LINK: http://www.flickr.com/​photos/x_tan/654317554​7/

I would be interested to see the same test at a higher ISO, maintaining 30 sec exposure and using higher aperture. The higher ISO will create a bit more noise and give a better indication of the value of the long exposure noise reduction.

smarti77 wrote in post #13572802
I would be interested to see the same test at a higher ISO, maintaining 30 sec exposure and using higher aperture. The higher ISO will create a bit more noise and give a better indication of the value of the long exposure noise reduction.

Interested in this as well - usually my setting is set to off. I've tested it a long time ago and saw little difference...but I remember I was at a lower ISO w/exposure being right around 30 sec.