November 26, 2014, 01:29:51 PM

Author Topic: Which camera setting affect the RAW image ? (NR - Color - Sharpness - etc...)  (Read 8190 times)

fanfan

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Hello,

I have a 5D MKIII and 7D
I have switch from Nikon to Canon about a year ago
I would like to know, which camera setting affect the RAW image
When I was using Nikon, on some model, the long exposure noise reduction was clearly affecting not only the JPEG but also RAW image

What about Canon? is there any setting (Noise reduction, color, contrast, sharpness, in camera color filter for monochrome image) that will affect the RAW image?
If so, which one?

Thanks for your help
This is my first post, so I want to say hi to everyone :)

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neuroanatomist

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The only one that directly affects RAW is Long Exposure NR, since that takes a dark frame after the exposure and subtracts that from the RAW file before writing it to the card.  Note that with Canon, when you set Long Exp NR to off, it really is off (with Nikon, it isn't at least on some models, and there is a median blur filter applied as well, google 'Nikon Mode 3 NR').

The other setting that 'sort of' affects the RAW file is Highlight Tone Priority.  This doesn't really modify the RAW data, only the metadata.  The camera uses an ISO that's 1 stop less than selected (which is why ISO 100 is unavailable with HTP on), i.e if you select ISO 400, the camera is exposing at ISO 200 (but reporting ISO 400 in the metadata), then it applies a selective tone curve to boost the signal but preserve the highlights.  DPP and other RAW converters recognize the HTP flag in the metadata - DPP will apply Canon's tone curve during conversion, other converters will apply their versions. but some converters don't recognize the flag and will just show you an underexposed image.

Do note that NR, color, contrast, saturation, etc., including those settings as applied by a Picture Style, can indirectly affect a RAW image.  For a RAW image, the camera generates a JPG preview image that's embedded in the RAW file.  That JPG preview is generated using the in-camera settings (picture style, ALO, etc.) even when shooting RAW, it's what is shown on the LCD review, and it's used to generate the histogram.  That means if you use the histogram or 'blinkies' (blown highlight alert) to judge exposure, you may expose incorrectly, and that obviously affects the RAW image.  You may want to use the Neutral picture style to get a closer approximation of how the RAW file will look, as a basis for the histogram and highlight alert.
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jointdoc

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Thank you neuroanatomist.  I have always wanted a clear explanation of this and you have provided it.
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Tcapp

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The only one that directly affects RAW is Long Exposure NR, since that takes a dark frame after the exposure and subtracts that from the RAW file before writing it to the card.  Note that with Canon, when you set Long Exp NR to off, it really is off (with Nikon, it isn't at least on some models, and there is a median blur filter applied as well, google 'Nikon Mode 3 NR').

The other setting that 'sort of' affects the RAW file is Highlight Tone Priority.  This doesn't really modify the RAW data, only the metadata.  The camera uses an ISO that's 1 stop less than selected (which is why ISO 100 is unavailable with HTP on), i.e if you select ISO 400, the camera is exposing at ISO 200 (but reporting ISO 400 in the metadata), then it applies a selective tone curve to boost the signal but preserve the highlights.  DPP and other RAW converters recognize the HTP flag in the metadata - DPP will apply Canon's tone curve during conversion, other converters will apply their versions. but some converters don't recognize the flag and will just show you an underexposed image.

Do note that NR, color, contrast, saturation, etc., including those settings as applied by a Picture Style, can indirectly affect a RAW image.  For a RAW image, the camera generates a JPG preview image that's embedded in the RAW file.  That JPG preview is generated using the in-camera settings (picture style, ALO, etc.) even when shooting RAW, it's what is shown on the LCD review, and it's used to generate the histogram.  That means if you use the histogram or 'blinkies' (blown highlight alert) to judge exposure, you may expose incorrectly, and that obviously affects the RAW image.  You may want to use the Neutral picture style to get a closer approximation of how the RAW file will look, as a basis for the histogram and highlight alert.

I love the blinkies. :)
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marek.sykora

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What about noise when shooting with HTP=on? Does it mean when I shooting at iso1600 it's in fact iso 800 in term of noise? I have always set HTP on, because results look better for me. Some people claims 7D is too noisy but I happy with iso 1600...

Similar to primary issue. Picture style affects movie, am I right? There is no way to change it easily, right? So it's a good idea to have neutral style for still and some colorful for movie.

neuroanatomist

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What about noise when shooting with HTP=on? Does it mean when I shooting at iso1600 it's in fact iso 800 in term of noise? I have always set HTP on, because results look better for me. Some people claims 7D is too noisy but I happy with iso 1600...

Not exactly - pushing the exposure increases noise, meaning with HTP you get a differential increase in shadow noise in the image.

Similar to primary issue. Picture style affects movie, am I right? There is no way to change it easily, right? So it's a good idea to have neutral style for still and some colorful for movie.

True.  You can also download a Technicolor CineStyle picture style for shooting video.
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fanfan

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Thanks a lot for the explanation, this is exactly what I wanted to know :)

One more question... Long exposure NR, does it do a good job on Canon camera or better turn it off and fix the image in Lightroom or DPP ?

Thanks again

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dr croubie

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Long exposure NR is a bit different to normal NR.

Normal NR, software scans the image and picks out pixels that aren't coloured they way they should be ('should be' is based on what the pixels around them look like).

Long exposure NR is different, as neuro said, the camera takes two photos, one normal one with shutter open, one with the shutter closed. the one with the shutter closed is what the sensor 'sees' all the time, ie where there's noise anyway. So by subtracting that from the normal image, it gets rid of the noise that is always present (like dead-pixels, at least in theory).

Basically, it's always a good thing to have Long Exp NR on all the time (it only happens above 1-second exposures anyway), it's always on on my 7D.

The only times I turn it off are:
- when you're capturing action (not that you'd really capture action with 1-second or longer exposures).
- you're impatient (or your better half is impatient, or it's just freezing outside and you want to get inside quicker)
- capturing star-trails (or other trails) or other HDR work (especially with moving clouds), basically where you're going to merge a lot of files together afterwards. If you're only taking one 30-second exposure every minute (where the other 30-seconds is being used to capture the dark-frame), then your star-trails may have gaps in the final picture.


It's different to the NR you get in DxO, DPP, Lightroom, etc. Long Exposure NR doesn't make your pictures softer like normal NR does. You can probably get the least noise when using both types of NR together.
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neuroanatomist

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If you're taking a long exposure, especially with dark areas in the image, use long exposure NR in camera.  The other option (often used by astrophotographers) is to take a dark frame manually and subtract it (using appropriate software) in post.  'Regular' NR isn't a good substitute.
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dude

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I have a 5D iii and I Long Exposure NR set to Auto. I have been taking some really long photo's lately. Some over 15 minutes. I shoot in RAW and I don't experience any wait between photo to start waiting on a dark frame.

If I take a 30 second picture, are you all sure there is a 30 second dark frame being taken and not just a quick 1 second dark frame?
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neuroanatomist

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I have a 5D iii and I Long Exposure NR set to Auto. I have been taking some really long photo's lately. Some over 15 minutes. I shoot in RAW and I don't experience any wait between photo to start waiting on a dark frame.

If I take a 30 second picture, are you all sure there is a 30 second dark frame being taken and not just a quick 1 second dark frame?

The Auto setting applies Long Exposure NR if the camera 'thinks' there's enough image noise to warrant it. If you're not waiting on a dark frame, the camera doesn't think NR is needed.  Try Enable. Note that the manual states Enable may reduce noise that the Auto setting can't detect c
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dude

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I enabled it. Took a series of long exposures. No difference. Are we sure about this dark frame behavior? It has never happened to me and I have shot a lot of long exposures the last few weeks.
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Jesse

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There seems to always be a longish buffer time after I take a 30 second or longer exposure with my 5D3. Is that because of NR? I don't remember it taking this long with my 5D2....
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neuroanatomist

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I enabled it. Took a series of long exposures. No difference. Are we sure about this dark frame behavior? It has never happened to me and I have shot a lot of long exposures the last few weeks.

I'm sure.  The dark frame isn't always the same duration as the exposure, depending on the exposure duration. With exposures in the ~1-5 s range, it is, but with exposures longer than ~5 s, the dark frame is ~5 s. The 'longish buffer time' Jesse mentions isn't buffering, it's the dark frame.  Watch that red light: it's on during the long exposure, then you'll hear the shutter close, but the light stays on for a few seconds - that's the dark frame being acquired.
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dude

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So we are all in agreement what I put in bold (and increased font size) below is incorrect information?

Long exposure NR is a bit different to normal NR.

Normal NR, software scans the image and picks out pixels that aren't coloured they way they should be ('should be' is based on what the pixels around them look like).

Long exposure NR is different, as neuro said, the camera takes two photos, one normal one with shutter open, one with the shutter closed. the one with the shutter closed is what the sensor 'sees' all the time, ie where there's noise anyway. So by subtracting that from the normal image, it gets rid of the noise that is always present (like dead-pixels, at least in theory).

Basically, it's always a good thing to have Long Exp NR on all the time (it only happens above 1-second exposures anyway), it's always on on my 7D.

The only times I turn it off are:
- when you're capturing action (not that you'd really capture action with 1-second or longer exposures).
- you're impatient (or your better half is impatient, or it's just freezing outside and you want to get inside quicker)
- capturing star-trails (or other trails) or other HDR work (especially with moving clouds), basically where you're going to merge a lot of files together afterwards. If you're only taking one 30-second exposure every minute (where the other 30-seconds is being used to capture the dark-frame), then your star-trails may have gaps in the final picture.


It's different to the NR you get in DxO, DPP, Lightroom, etc. Long Exposure NR doesn't make your pictures softer like normal NR does. You can probably get the least noise when using both types of NR together.
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