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Author Topic: Exposing To The Right  (Read 17718 times)
cwood
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« on: August 09, 2011, 09:19:05 AM »
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I've read and understand Michael's argument for exposing to the right. I can't disagree in general but there are some counterarguments including the matter of color shift that can occur when overexposing. I certainly noticed some of that when I owned a 5D2 and I attempted to push exposure a half or full EV. 

There are also some sensors available, including the new 16 meg manufactured by SONY, used in various SONY, Nikon and Pentax models, that are extremely clean in shadow and dark areas, that invite the opposite. Based on my experience with a Pentax K-5 at ISO 80, I can underexpose a full stop and using LR, can bring up fill light, adjust levels, brightness and contrast, and wind up with a far more pleasing image than going the other direction by overexposing.  Although I can't push the underexposure quite as far, I've found I can go - half an EV with my 645D and get a better result than by overexposing a half EV.

I would be interested in learning what others here have found in this regard.
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Scott O.
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« Reply #1 on: August 09, 2011, 01:58:10 PM »
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I always expose to the right and have not noticed any image/color degredation doing this, using Lightroom.  Normally, a little bump of the blacks causes the colors to 'pop'.
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Guillermo Luijk
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« Reply #2 on: August 09, 2011, 03:43:32 PM »
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there are some counterarguments including the matter of color shift that can occur when overexposing. I certainly noticed some of that when I owned a 5D2 and I attempted to push exposure a half or full EV

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Wayne Fox
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« Reply #3 on: August 10, 2011, 07:55:27 PM »
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I've read and understand Michael's argument for exposing to the right. I can't disagree in general but there are some counterarguments including the matter of color shift that can occur when overexposing. I certainly noticed some of that when I owned a 5D2 and I attempted to push exposure a half or full EV. 


By over exposing I assume you mean exposing more than your camera suggests, which is providing you information as though film were in the camera?

EttR is not overexposing.  It is using a different method to determine exposure and then a different method to develop the image.  I have seen no color shift that is do due increasing exposure except in cases where one or more channels were clipped.  I've seen this mentioned a few times, so I assume someone out there is making this claim, but as was pointed out, I haven't seen any actual examples of this happening.

Certainly if there were color shifts, it would most likely something in post processing, not from using EttR to base the exposure on.
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Martin Kristiansen
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« Reply #4 on: August 11, 2011, 12:10:43 AM »
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I have not noticed a colour shift on my camera (Aptus 12). What I do notice is much better colour in the shadows. The less noise is a no brainer but the improvements in colour are a great bonus. In the past I was always bothered by the way digital seemed to get monochromatic in the shadows.
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stamper
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« Reply #5 on: August 11, 2011, 03:17:25 AM »
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If someone is using ACR then they should ZERO out all of the sliders before making a judgement on the colour shifts. Even having a WB setting Daylight can influence colour. Changing as shot to daylight can produce a clipping warning. I have used Auto WB in my Nikon d700 camera which came up as as shot in ACR and when I changed it to WB daylight a highlight red warning appeared in ACR. A lot is happening in the background after importation to ACR, or Lightroom for that matter.
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NigelC
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« Reply #6 on: August 11, 2011, 06:30:09 AM »
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Generally use ETTR in the same way I used to use the zone system, as a guide rather than religious observance, but one problem is I don't entirely trust the accuracy of the histogram on DSLRs. I understand that it's based on the embedded jpeg and I can never be sure if I've clipped the highlights or not.
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theguywitha645d
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« Reply #7 on: August 11, 2011, 10:37:11 AM »
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ETTR increases contrast and saturation.
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stamper
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« Reply #8 on: August 11, 2011, 10:41:51 AM »
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The lighter an image gets then the opposite - imo - happens. Whether it changes hue is open for debate?
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Guillermo Luijk
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« Reply #9 on: August 11, 2011, 11:30:52 AM »
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ETTR increases contrast and saturation.

Wrong. ETTR just modifies visible noise. Any other image parameter remains unaltered thanks to sensor linearity.



« Last Edit: August 11, 2011, 12:11:05 PM by Guillermo Luijk » Logged

jeremypayne
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« Reply #10 on: August 11, 2011, 12:53:58 PM »
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I certainly noticed some of that when I owned a 5D2 and I attempted to push exposure a half or full EV. 

Color shifts when you alter exposure by 1/2 stop?  I would very much like to see an example of this.
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digitaldog
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« Reply #11 on: August 11, 2011, 01:14:30 PM »
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Color shifts when you alter exposure by 1/2 stop?  I would very much like to see an example of this.

I seen none in Guillermo‘s examples. And even if there were, seems easy to adjust.

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Andrew Rodney
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PeterAit
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« Reply #12 on: August 11, 2011, 07:22:20 PM »
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I think that ETTR is one of those techniques that has a valid theoretical basis but no benefit in the real world. This of course excludes pixel-peeping!
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Peter
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« Reply #13 on: August 11, 2011, 07:24:25 PM »
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I think that ETTR is one of those techniques that has a valid theoretical basis but no benefit in the real world. This of course excludes pixel-peeping!

The same thing could be said for incorrectly exposing film, running a snip test then fixing the issue by push processing.
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Andrew Rodney
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« Reply #14 on: August 11, 2011, 09:02:00 PM »
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I think that ETTR is one of those techniques that has a valid theoretical basis but no benefit in the real world. This of course excludes pixel-peeping!

Hum...ok.

I guess there's a range of opinions about the importance of image quality. Personally, I leave no stone unturned. If there's something I can do that's not really difficult (and ETTR is pretty easy) I'm happy to do it to get a better quality image.

It's a shame to leave image quality on the table when just a little bit of effort can improve it...so, do you use 8-bit, sRGB as a PS working space?

Just trying to gauge your level of, uh, commitment :~)
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Wayne Fox
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« Reply #15 on: August 12, 2011, 01:03:20 AM »
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I think that ETTR is one of those techniques that has a valid theoretical basis but no benefit in the real world. This of course excludes pixel-peeping!
Curious what you are basing that on.  Did you actually try it? Because if you do and do it right, you will see a clear difference with cleaner shadows and better detail in your shadows in prints, especially larger ones where noise becomes much more obvious.

Certainly this only applies some of the time in the right circumstances and probably doesn't help much if you only print 4x6's and put 500px images on the web, but using it really isn't difficult or challenging. 
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Eric Myrvaagnes
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« Reply #16 on: August 12, 2011, 08:37:02 AM »
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I think that ETTR is one of those techniques that has a valid theoretical basis but no benefit in the real world. This of course excludes pixel-peeping!
Back in the Dark Ages (i.e., Before Digital) I recall that many photographers said similar things about the Zone System, mainly because you had to do a little work testing your equipment and materials in order to be able to use it effectively. IMHO, the same applies to ETTR.

Eric M.
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Wayne Fox
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« Reply #17 on: August 13, 2011, 01:26:52 AM »
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Thought I would add one personal IMHO that I haven't noticed in any of the EttR discussions so far.

In my mind EttR isn't just about moving the data to the right to reduce noise and increase quality.  Personally I think it's the correct way to determine almost all exposures regardless of the contrast range of the scene vs. the dynamic range of the sensor.

Certainly if the scenes contrast range is less the the sensors DR, you maximize the benefits of EttR.

However, if you base your exposure on the highlights just short of clipping, you get the maximum information in your shadows, even if they clip.  Often by opening up the exposure a little, you get enough shadow information to not require HDR, especially with some of today current cameras (with my IQ180, I really haven't found a time where I had to use HDR).  If you let the camera choose a setting that will render a pleasing Jpeg (the goal of the camera makers) you in may block up your shadows too far.

Exposures based on the highlight clipping point is just the logical way of determine a digital exposure because the goal in digital capture is maximizing the data, not creating a pleasing on camera image.
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ErikKaffehr
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« Reply #18 on: August 13, 2011, 01:50:06 AM »
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Hi,

Absolutely agree with Wayne.

There are three additional points in the discussion.

1) Never clip important highlights in any channel!

2) The histogram is conservative, as it is not calculated from raw data. So it's possible to push exposure a bit longer, but we don't actually now how far.

3) At least on some sensors, nonlinearity close to saturation may cause color shift according to some very knowledgeable people.

The final question may be how white balance messes up the exposure of each channel?

Best regards
Erik
Thought I would add one personal IMHO that I haven't noticed in any of the EttR discussions so far.

In my mind EttR isn't just about moving the data to the right to reduce noise and increase quality.  Personally I think it's the correct way to determine almost all exposures regardless of the contrast range of the scene vs. the dynamic range of the sensor.

Certainly if the scenes contrast range is less the the sensors DR, you maximize the benefits of EttR.

However, if you base your exposure on the highlights just short of clipping, you get the maximum information in your shadows, even if they clip.  Often by opening up the exposure a little, you get enough shadow information to not require HDR, especially with some of today current cameras (with my IQ180, I really haven't found a time where I had to use HDR).  If you let the camera choose a setting that will render a pleasing Jpeg (the goal of the camera makers) you in may block up your shadows too far.

Exposures based on the highlight clipping point is just the logical way of determine a digital exposure because the goal in digital capture is maximizing the data, not creating a pleasing on camera image.

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Guillermo Luijk
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« Reply #19 on: August 13, 2011, 05:05:23 AM »
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if you base your exposure on the highlights just short of clipping, you get the maximum information in your shadows, even if they clip.  Often by opening up the exposure a little, you get enough shadow information to not require HDR, especially with some of today current cameras (with my IQ180, I really haven't found a time where I had to use HDR).  If you let the camera choose a setting that will render a pleasing Jpeg (the goal of the camera makers) you in may block up your shadows too far.

Exposures based on the highlight clipping point is just the logical way of determine a digital exposure because the goal in digital capture is maximizing the data, not creating a pleasing on camera image.

What you are saying here is correct, but I wouldn't use the terms 'clip' or 'block' for the shadows. If the dynamic range of the scene is not a problem (i.e. camera's DR is greater than the scene's), optimal digital exposure is the consequence of the following asymmetry in digital sensors:
- Highlights information is boolean: if they clip you loose everything, if they don't clip you have everything, and you have it with maximum quality
- Shadows information is progressive: they don't clip, they just have a higher or lower SNR (i.e. visible noise once processed)

So the logical reference for digital exposure should be the highlights.


3) At least on some sensors, nonlinearity close to saturation may cause color shift according to some very knowledgeable people.

The final question may be how white balance messes up the exposure of each channel?

I'm still looking for a demonstration of that colour shift.

I reverse engineered a white balance setting in ACR, and although its implementation can be somewhat more sophisticated (matrix operations are involved), it is basically an individual exposure correction for each channel prior to the demosaicing process:


ACR Daylight to Tungsten WB comparision

Regards
« Last Edit: August 13, 2011, 05:08:08 AM by Guillermo Luijk » Logged

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