Noise and ETTR

Started 6 months ago | Questions
roperc3
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Noise and ETTR
6 months ago

Dear fellow forumites,

I have a question regarding noise, and how best to avoid it.  I'm aware of the usual preventative measures - using as low an ISO as possible, improving it in PP etc. - but I was wondering, having seen mention of noise and ETTR (exposing to the right) are there are any other ways of reducing noise at the time of shooting?

I might have got the wrong end of the stick, but I recall reading that noise is reduced if you expose to the right - is this correct?  I don't normally change the EV in camera before taking a shot and rely on making exposure adjustments in PP, is this a bad thing?  I've never had an image (yet) that couldn't be recovered in Lightroom using the appropriate sliders, but I've a sneaky suspicion that making these adjustments in PP might actually exacerbate noise.

Should I be making sure the image is as perfectly exposed as possible before taking the shot rather than relying on my trusty OMD-EM5's assessment?

And, what exactly does exposing to the right mean?  Sorry for being such an ignoramus - I have hitherto assumed it would benefit my pictures, but I don't actually know what it means.

Some info about me:

-  I always shoot RAW, but find the JPEG results from the EM5 sometimes surpass my ability to alter RAW images and manipulate noise/contrast etc.

-  I find that the histogram in LR during PP is almost always bunched up (and touching) in the left hand side, before I've made any adjustments - could this be chronic underexposure?

-  I use the exposure, recovery and fill light sliders in LR with blinkies for highlight/shadows to asses what I need to correct

Any help greatly appreciated.

Chris

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GeorgianBay1939
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Re: Noise and ETTR
In reply to roperc3, 6 months ago

I think that this excellent article (and it's linked references) would be of assistance to you:

http://www.dpreview.com/articles/6641165460/ettr-exposed

It seems that you are at the stage where a fundamental understanding of the factors influencing your exposure/noise decisions would be more productive (compared to depending on "recipes").

I hope that this helps.

Tom

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roperc3
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Re: Noise and ETTR
In reply to GeorgianBay1939, 6 months ago

Wow, thank you very much - only read the first paragraph of that article and can already tell this is going to answer a lot of my questions!

Appreciate your help.

Chris

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Ido S
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Re: Noise and ETTR
In reply to roperc3, 6 months ago

Haven't clicked into the link that GeorgianBay1939 gave you, but I'll explain to you how I go by shooting with my OM-D E-M5.

First, You should understand what ISO truly is. By increasing the ISO, the sensor's voltage increases (something like that, I'm not great at electricity and all that stuff). This action is actually quite similar in its effect to bumping out the "Exposure" or Brightness in Lightroom. (I put Exposure in quotation marks, because by using that slider in Lightroom, the actual exposure is obviously not changed.) And so much like raising the ISO increases (or accentuates) noise, raising the Exposure or Brightness sliders accentuates noise. And I say accentuate, because it's not introducing noise - it's just making stuff brighter, and with it the noise that was there before making the adjustment.

So in Raw processing, the best thing you can do to fight noise, is to stay away from bringing up the Exposure or Brightness, or pushing the shadows too far (since you're using an old version of Lightroom, or an old processing version, it's called Fill Light). Whatever noise that's already there, is accentuated by this action.

In contrast, taking the Exposure or Brightness sliders down quite a lot, does not accentuate noise. Therefore, if you want the deep shadows of a photo to be lighter than what the automatic exposure gives you, then use the exposure compensation feature and over-expose the shot, while keeping an eye on the highlights and making sure they are not burned. I find that the E-M5's blinkies by default are too sensitive and for me sometimes hard to see, so either tweak the settings or do as I do, and shoot with a live histogram instead.

That way, the Raw file (and out-of-camera JPEG) may look too bright when you bring it into Lightroom, but you will also notice that the histogram's right side does not touch the edge (if you over-exposed correctly). Then you can darken down the image if needed, while keeping the shadows at hand and controlling them as you'd like. It may feel very refreshing at first - when I started doing that, I completely stopped bracketing exposures and combining them in an HDR software. Now I do 99% of my work on a single Raw file, when previously it was somewhere between 80% and 90%.

Make sure that when you're using the exposure compensation to over-expose (or rather, expose to the right), the shutter speed is changed, and not the ISO or the aperture. As I explained previously, bumping up the ISO will do you no good, as it would be exactly like taking the dark, zeroed-out exposure into Lightroom, and using the sliders to brighten the image. And the risk at changing the aperture to alter the exposure should be obvious - the depth of field will be changed!

If you haven't understood by now, then no, the ETTR method does not by itself reduce the amount of noise. But if done correctly, it will definitely correlate to that.

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GeorgianBay1939
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Re: Noise and ETTR
In reply to Ido S, 6 months ago

Very good post!   A little rough around the edges due to vocabulary issues but you've got the "guts" of the issue well described .... I think!  

BUT

If you want to go the next step, improve your vocabulary, and see some of the nuances of ETTR and Noise, I'd recommend that you read the link(s) I refer to above .  Although I understood the basics (as you do) I still found some rich stuff by reading (and rereading) Golliwop and Martinec.

Gollywop's first opus, Exposure Vs Brightening is probably a good place to start, as it provides the background to your procedures.

Martinec's work on Noise, Dynamic Range and Bit Depth in Digital SLRs   is a little more demanding & a little dated but applies to Mirrorless Cameras very well.  It really helped me understand and develop good techniques when shooting RAW.

Gollywop refers to the 3rd part of Martinec's work in his ETTR Exposed .

All very good stuff .... especially for RAW shooters.

Tom

Ido S wrote:

Haven't clicked into the link that GeorgianBay1939 gave you, but I'll explain to you how I go by shooting with my OM-D E-M5.

First, You should understand what ISO truly is. By increasing the ISO, the sensor's voltage increases (something like that, I'm not great at electricity and all that stuff). This action is actually quite similar in its effect to bumping out the "Exposure" or Brightness in Lightroom. (I put Exposure in quotation marks, because by using that slider in Lightroom, the actual exposure is obviously not changed.) And so much like raising the ISO increases (or accentuates) noise, raising the Exposure or Brightness sliders accentuates noise. And I say accentuate, because it's not introducing noise - it's just making stuff brighter, and with it the noise that was there before making the adjustment.

So in Raw processing, the best thing you can do to fight noise, is to stay away from bringing up the Exposure or Brightness, or pushing the shadows too far (since you're using an old version of Lightroom, or an old processing version, it's called Fill Light). Whatever noise that's already there, is accentuated by this action.

In contrast, taking the Exposure or Brightness sliders down quite a lot, does not accentuate noise. Therefore, if you want the deep shadows of a photo to be lighter than what the automatic exposure gives you, then use the exposure compensation feature and over-expose the shot, while keeping an eye on the highlights and making sure they are not burned. I find that the E-M5's blinkies by default are too sensitive and for me sometimes hard to see, so either tweak the settings or do as I do, and shoot with a live histogram instead.

That way, the Raw file (and out-of-camera JPEG) may look too bright when you bring it into Lightroom, but you will also notice that the histogram's right side does not touch the edge (if you over-exposed correctly). Then you can darken down the image if needed, while keeping the shadows at hand and controlling them as you'd like. It may feel very refreshing at first - when I started doing that, I completely stopped bracketing exposures and combining them in an HDR software. Now I do 99% of my work on a single Raw file, when previously it was somewhere between 80% and 90%.

Make sure that when you're using the exposure compensation to over-expose (or rather, expose to the right), the shutter speed is changed, and not the ISO or the aperture. As I explained previously, bumping up the ISO will do you no good, as it would be exactly like taking the dark, zeroed-out exposure into Lightroom, and using the sliders to brighten the image. And the risk at changing the aperture to alter the exposure should be obvious - the depth of field will be changed!

If you haven't understood by now, then no, the ETTR method does not by itself reduce the amount of noise. But if done correctly, it will definitely correlate to that.

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smithling
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Re: Noise and ETTR
In reply to roperc3, 6 months ago

Don't bother with ETTR unless you have an extremely tricky scene to contend with.

Other people have provided you good responses about what ETTR is, and what the benefits are. But ETTR was established when the dynamic range of digital camera sensors were terrible. It's still a valid technique, but today, the noise amount between pushing shadows in post, and ETTR and then pulling them down, is negligible. The sensors today are really good. Professionals don't bother, and most photographers (artists) I know don't bother either because the difference is simply not noticeable in prints.

IMHO, in general, it is a waste of time. Try it out, and then ask yourself honestly if the trouble is worth the time and mental effort.

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Anders W
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Re: Noise and ETTR
In reply to roperc3, 6 months ago

roperc3 wrote:

Dear fellow forumites,

I have a question regarding noise, and how best to avoid it. I'm aware of the usual preventative measures - using as low an ISO as possible, improving it in PP etc. - but I was wondering, having seen mention of noise and ETTR (exposing to the right) are there are any other ways of reducing noise at the time of shooting?

I might have got the wrong end of the stick, but I recall reading that noise is reduced if you expose to the right - is this correct?

Yes.

I don't normally change the EV in camera before taking a shot and rely on making exposure adjustments in PP, is this a bad thing? I've never had an image (yet) that couldn't be recovered in Lightroom using the appropriate sliders, but I've a sneaky suspicion that making these adjustments in PP might actually exacerbate noise.

Your sneaky suspicion is correct. Changing the "exposure" (or rather the brightness, the exposure remains what it was) in PP affects the visibility of the noise (although the noise itself, just as the exposure, remains what it was). If you push in PP (increase the brightness), you will make the noise more visible. If instead you pull in PP (decrease the brightness), you will make it less visible.

Should I be making sure the image is as perfectly exposed as possible before taking the shot rather than relying on my trusty OMD-EM5's assessment?

Yes you should try to make sure the image is as perfectly exposed as possible when out shooting. The E-M5 will help you do that if you use the tools it provides right. See below for further information.

And, what exactly does exposing to the right mean? Sorry for being such an ignoramus - I have hitherto assumed it would benefit my pictures, but I don't actually know what it means.

"Exposing to the right" refers to the histogram. It simply means that you should give the image enough exposure to bring those highlights that you care to preserve right up to the clipping point (in RAW) but not beyond. Depending on how contrasty the scene is, this may sometimes mean that you "overexpose" (expose such as to make the OOC jpeg look overly bright) and decrease the brightness in PP and sometimes that you "underexpose" (expose such as to make the OOC jpeg look overly dark) and then push the shadows in PP.

In addition to the link to the article you already got from GeorgianBay1939, you might want to have a look at this recipe for exposure with the E-M5 specifically:

http://www.dpreview.com/forums/post/51169217

What I should mention in addition to what is said in that post is that I have my highlight warning level set to 255.

Note that you can sometimes improve the image quality noticeably in scenes with high dynamic range by shooting multiple images at different exposure and then merging/aligning them in PP. An easy and inexpensive way to do it is by means of an LR-plugin called LR/Enfuse (which costs you a "donation" of two GBP). The two images below, were both produced by such means. Both have greater dynamic range than any current camera could give you in a single shot.

Some info about me:

- I always shoot RAW, but find the JPEG results from the EM5 sometimes surpass my ability to alter RAW images and manipulate noise/contrast etc.

This may mean that you have to improve your PP skills. Although the OOC jpegs of the E-M5 are certainly not bad, you should be able to get better results from LR across the board.

- I find that the histogram in LR during PP is almost always bunched up (and touching) in the left hand side, before I've made any adjustments - could this be chronic underexposure?

Yes, that may be a sign that you are systematically giving the camera less exposure than it can take (and you can give it). A histogram like the one you describe is not always wrong (if there are prominent highlights that are close to clipping at the other, right end) but as a rule it should look different.

- I use the exposure, recovery and fill light sliders in LR with blinkies for highlight/shadows to asses what I need to correct

Your mention of the "fill light slider" suggests that you are still on LR 3.x. I would strongly advice you to upgrade to a later version. For example, the effect of the highlight slider improved noticeably in LR 4.x as did the ability to deal with CA (chromatic aberration). There are significant improvements in version 5.x too.

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Anders W
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Re: Noise and ETTR
In reply to smithling, 6 months ago

smithling wrote:

Don't bother with ETTR unless you have an extremely tricky scene to contend with.

Other people have provided you good responses about what ETTR is, and what the benefits are. But ETTR was established when the dynamic range of digital camera sensors were terrible. It's still a valid technique, but today, the noise amount between pushing shadows in post, and ETTR and then pulling them down, is negligible. The sensors today are really good. Professionals don't bother, and most photographers (artists) I know don't bother either because the difference is simply not noticeable in prints.

IMHO, in general, it is a waste of time. Try it out, and then ask yourself honestly if the trouble is worth the time and mental effort.

Once you have figured out how to do it, it doesn't take any extra time or mental effort at all. And I would think there are many experienced and technically skilled photographers here that would disagree with your assessment (as I certainly do) of whether it is worth learning how to do it. Sensors have become better than they were, yes, but if you learn how to use them right, the results will be better still. Why wouldn't you want to take advantage of that fact?

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Rocky ID Olympian
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Re: Noise and ETTR
In reply to roperc3, 6 months ago

Dear fellow forumites,

I have a question regarding noise, and how best to avoid it.  I'm aware of the usual preventative measures - using as low an ISO as possible, improving it in PP etc. - but I was wondering, having seen mention of noise and ETTR (exposing to the right) are there are any other ways of reducing noise at the time of shooting?

I might have got the wrong end of the stick, but I recall reading that noise is reduced if you expose to the right - is this correct?  I don't normally change the EV in camera before taking a shot and rely on making exposure adjustments in PP, is this a bad thing?  I've never had an image (yet) that couldn't be recovered in Lightroom using the appropriate sliders, but I've a sneaky suspicion that making these adjustments in PP might actually exacerbate noise.

Should I be making sure the image is as perfectly exposed as possible before taking the shot rather than relying on my trusty OMD-EM5's assessment?

And, what exactly does exposing to the right mean?  Sorry for being such an ignoramus - I have hitherto assumed it would benefit my pictures, but I don't actually know what it means.

Some info about me:

-  I always shoot RAW, but find the JPEG results from the EM5 sometimes surpass my ability to alter RAW images and manipulate noise/contrast etc.

-  I find that the histogram in LR during PP is almost always bunched up (and touching) in the left hand side, before I've made any adjustments - could this be chronic underexposure?

-  I use the exposure, recovery and fill light sliders in LR with blinkies for highlight/shadows to asses what I need to correct

Any help greatly appreciated.

Chris

ETTR works only for RAW not JPEG

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yyr
yyr
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Re: Noise and ETTR
In reply to Anders W, 6 months ago

Note that you can sometimes improve the image quality noticeably in scenes with high dynamic range by shooting multiple images at different exposure and then merging/aligning them in PP. An easy and inexpensive way to do it is by means of an LR-plugin called LR/Enfuse (which costs you a "donation" of two GBP).

Anders, that looks interesting as a bit of software. It seems from your description that you're  simply merging the 2 images rather than relying on HDR algorithms and all the pain that can go with that?

Yaelle

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Anders W
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Re: Noise and ETTR
In reply to yyr, 6 months ago

yyr wrote:

Note that you can sometimes improve the image quality noticeably in scenes with high dynamic range by shooting multiple images at different exposure and then merging/aligning them in PP. An easy and inexpensive way to do it is by means of an LR-plugin called LR/Enfuse (which costs you a "donation" of two GBP).

Anders, that looks interesting as a bit of software. It seems from your description that you're simply merging the 2 images rather than relying on HDR algorithms and all the pain that can go with that?

Yes. It is technically known as "exposure-blending". The difference compared to "true" HDR based on multiple exposures is that the images are merged with a tone curve already applied. It is usually easy to get palatable results and the software itself as well as your own processing (via LR) of the input gives you some control of the outcome. The number of shots can be only two (as in the first of the two samples I show) but you can use more if you like. The second sample, where the scene has extremely high dynamic range, is based on nine shots, all with the 12/2 at f/4, and a shutter speed varying from 1/8 s to 30 s.

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yyr
yyr
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Re: Noise and ETTR
In reply to Anders W, 6 months ago

Anders W wrote:

yyr wrote:

Note that you can sometimes improve the image quality noticeably in scenes with high dynamic range by shooting multiple images at different exposure and then merging/aligning them in PP. An easy and inexpensive way to do it is by means of an LR-plugin called LR/Enfuse (which costs you a "donation" of two GBP).

Anders, that looks interesting as a bit of software. It seems from your description that you're simply merging the 2 images rather than relying on HDR algorithms and all the pain that can go with that?

Yes. It is technically known as "exposure-blending". The difference compared to "true" HDR based on multiple exposures is that the images are merged with a tone curve already applied. It is usually easy to get palatable results and the software itself as well as your own processing (via LR) of the input gives you some control of the outcome. The number of shots can be only two (as in the first of the two samples I show) but you can use more if you like. The second sample, where the scene has extremely high dynamic range, is based on nine shots, all with the 12/2 at f/4, and a shutter speed varying from 1/8 s to 30 s.

I'm off to make a donation. I was reading about exposure-blending in a thread a couple of days ago. The guy who was using it was a PS user though and I don't want to go down that route. This seems like an excellent alternative. HDR can be great fun but it's not always the 'look' that I want. This sounds great and ideal. Thanks so much for the reference.

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Yaelle

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Andy Crowe
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How ETTR and ETTL work mathematically
In reply to roperc3, 6 months ago

To help visualise, here's what's happening with noise mathematically.

Lets say you're photographing a completely plain grey wall, which when correctly exposed the grey pixels are 50 brightness. Noise adds +-5 to that.

Thus with noise a line of pixels might be

55, 46, 54, 55, 48, 49, 50, 45, 55, 48, 48, 52, 51, 50, 47, 55, 54, 48, 55, 51

With the noise ranging from 45-55.

-

If you underexpose (so the grey pixels are just 25 brightness) you still get +-5 noise, so you have

20, 25, 22, 30, 20, 26, 21, 21, 23, 28, 29, 20, 27, 30, 24, 23, 22, 30, 24, 22

You then double the exposure in post to make 50 and get

40, 50, 44, 60, 40, 52, 42, 42, 46, 56, 58, 40, 54, 60, 48, 46, 44, 60, 48, 44

which if you compare to the correctly exposed pixels is more noisy, ranging from 40-60.

-

If you overexpose so the grey pixels are 75 +- 5 noise you get

76, 80, 78, 79, 79, 73, 75, 70, 79, 73, 70, 76, 73, 79, 78, 77, 80, 80, 72, 78

Which if you bring it back down to 50 in post makes

50, 53, 52, 52, 52, 48, 50, 47, 52, 48, 47, 50, 48, 52, 52, 51, 53, 53, 48, 52

With less noise with a range of just 47 - 53

-

The only problem with ETTR is if your pixels go over 100% brightness you can't bring them back down in post anymore, so if you go too far to the right you may end up with white or off-coloured patches where the colour channels have clipped.

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Anders W
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Re: Noise and ETTR
In reply to yyr, 6 months ago

yyr wrote:

Anders W wrote:

yyr wrote:

Note that you can sometimes improve the image quality noticeably in scenes with high dynamic range by shooting multiple images at different exposure and then merging/aligning them in PP. An easy and inexpensive way to do it is by means of an LR-plugin called LR/Enfuse (which costs you a "donation" of two GBP).

Anders, that looks interesting as a bit of software. It seems from your description that you're simply merging the 2 images rather than relying on HDR algorithms and all the pain that can go with that?

Yes. It is technically known as "exposure-blending". The difference compared to "true" HDR based on multiple exposures is that the images are merged with a tone curve already applied. It is usually easy to get palatable results and the software itself as well as your own processing (via LR) of the input gives you some control of the outcome. The number of shots can be only two (as in the first of the two samples I show) but you can use more if you like. The second sample, where the scene has extremely high dynamic range, is based on nine shots, all with the 12/2 at f/4, and a shutter speed varying from 1/8 s to 30 s.

I'm off to make a donation. I was reading about exposure-blending in a thread a couple of days ago. The guy who was using it was a PS user though and I don't want to go down that route. This seems like an excellent alternative. HDR can be great fun but it's not always the 'look' that I want. This sounds great and ideal. Thanks so much for the reference.

I think I know what you mean when you say that HDR does not always give you the "look" you want. HDR can be a form of art that you may or not like. What I am usually after is something that looks more natural and Enfuse usually gives me that. That LR/Enfuse makes it all possible without leaving LR is an additional bonus. Glad to be of help. I hope and think you made the right decision.

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jkrumm
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Re: Noise and ETTR
In reply to Anders W, 6 months ago

Enfuse/enblend a neat program, I agree. I haven't used it recently because I subscribed to the CC Lightroom/Photoshop deal and Photoshop's HDR method gives surprisingly natural looking results too (you adjust a 32bit tiff in Lightroom after the HDR blend).

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Anders W
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Re: How ETTR and ETTL work mathematically
In reply to Andy Crowe, 6 months ago

Andy Crowe wrote:

To help visualise, here's what's happening with noise mathematically.

Lets say you're photographing a completely plain grey wall, which when correctly exposed the grey pixels are 50 brightness. Noise adds +-5 to that.

Thus with noise a line of pixels might be

55, 46, 54, 55, 48, 49, 50, 45, 55, 48, 48, 52, 51, 50, 47, 55, 54, 48, 55, 51

With the noise ranging from 45-55.

-

If you underexpose (so the grey pixels are just 25 brightness) you still get +-5 noise, so you have

20, 25, 22, 30, 20, 26, 21, 21, 23, 28, 29, 20, 27, 30, 24, 23, 22, 30, 24, 22

You then double the exposure in post to make 50 and get

40, 50, 44, 60, 40, 52, 42, 42, 46, 56, 58, 40, 54, 60, 48, 46, 44, 60, 48, 44

which if you compare to the correctly exposed pixels is more noisy, ranging from 40-60.

-

If you overexpose so the grey pixels are 75 +- 5 noise you get

76, 80, 78, 79, 79, 73, 75, 70, 79, 73, 70, 76, 73, 79, 78, 77, 80, 80, 72, 78

Which if you bring it back down to 50 in post makes

50, 53, 52, 52, 52, 48, 50, 47, 52, 48, 47, 50, 48, 52, 52, 51, 53, 53, 48, 52

With less noise with a range of just 47 - 53

Although you are basically on the right track, that's not quite how it works. The noise does not stay constant as you vary the exposure. If it's originally +-5, as in your example, it will be less than that if you underexpose (before pushing) and more than that if you overexpose (before pulling). After pushing, it would still be higher, and after pulling, it would still be lower, than it was with the exposure you first exemplify.

The only problem with ETTR is if your pixels go over 100% brightness you can't bring them back down in post anymore, so if you go too far to the right you may end up with white or off-coloured patches where the colour channels have clipped.

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Anders W
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Re: Noise and ETTR
In reply to jkrumm, 6 months ago

jkrumm wrote:

Enfuse/enblend a neat program, I agree. I haven't used it recently because I subscribed to the CC Lightroom/Photoshop deal and Photoshop's HDR method gives surprisingly natural looking results too (you adjust a 32bit tiff in Lightroom after the HDR blend).

I am sure you are right that you can get natural-looking results with "real" HDR software too. It's primarily a matter of knowing how to get there.

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David Kieltyka
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Re: Noise and ETTR
In reply to roperc3, 6 months ago

Can you actually see noise in your output media of choice (prints, monitor/TV display, etc.)? If so is it objectionable to you? If so, then you can take steps to mitigate it...ETTR, post-processing NR, etc. If not, don't worry about it! Real-world results are all that matter.

-Dave-

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smithling
Regular MemberPosts: 300
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Re: Noise and ETTR
In reply to Anders W, 6 months ago

Anders W wrote:

smithling wrote:

Don't bother with ETTR unless you have an extremely tricky scene to contend with.

Other people have provided you good responses about what ETTR is, and what the benefits are. But ETTR was established when the dynamic range of digital camera sensors were terrible. It's still a valid technique, but today, the noise amount between pushing shadows in post, and ETTR and then pulling them down, is negligible. The sensors today are really good. Professionals don't bother, and most photographers (artists) I know don't bother either because the difference is simply not noticeable in prints.

IMHO, in general, it is a waste of time. Try it out, and then ask yourself honestly if the trouble is worth the time and mental effort.

Once you have figured out how to do it, it doesn't take any extra time or mental effort at all. And I would think there are many experienced and technically skilled photographers here

Where? At the dpreview.com forums? No problem. There's a vast, vast photographic world outside of this forum.

that would disagree with your assessment (as I certainly do) of whether it is worth learning how to do it.

Never did I say that it was a waste of time to learn ETTR. Please note that I said, "try it out." Sorry for the miscommunication.

Sensors have become better than they were, yes, but if you learn how to use them right, the results will be better still. Why wouldn't you want to take advantage of that fact?

With respect Anders, "use them right" and "better results" are merely subjective. Here's an opinion from another real professional that disagrees with you.

http://theonlinephotographer.typepad.com/the_online_photographer/2011/10/expose-to-the-right-is-a-bunch-of-bull.html

Based on my prints and output, ETTR is simply way overrated.

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cmpatti
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Re: Noise and ETTR
In reply to Anders W, 6 months ago

Anders W wrote:

In addition to the link to the article you already got from GeorgianBay1939, you might want to have a look at this recipe for exposure with the E-M5 specifically:

http://www.dpreview.com/forums/post/51169217

I have a question about the procedure outlined in this post. It calls for setting the largest aperture and the slowest shutter speed that will get the image and then pushing the histogram to the right by raising ISO. It's been my impression that achieving ETTR by increasing ISO doesn't accomplish any meaningful noise reduction because the ISO increase offsets the benefits of ETTR. Therefore, I've thought that ETTR is only really useful in low contrast, well-lighted situations where you can increase exposure at base ISO by reducing shutter speed without blowing out highlights. Since those situations aren't all that common, and since noise isn't usually a major concern in those situations, I haven't really taken the trouble to incorporate ETTR in my metering routine. Instead, my practice has been "shoot at the lowest ISO at which you can get the shutter speed you need" (since I'm generally shooting aperture priority).

So my question: is there any testing available that shows that raising ISO to achieve ETTR reduces noise? In other words, that ISO 200, f/4, 1/100 (with highlights a stop from the right) will produce more noise than ISO 400, f/4, 1/100? This would be useful to know.

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