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07-20-2016, 10:03 PM   #1
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Landscape: how to expose for the shadows

Hi folks.
I know how critical it is to expose correctly to avoid blown high lights. In single shot technique, I expose to the right with about +2ev above mid level, for the brightest part of the frame. In this way, the full range of the sensor is used.

That said, I now play with blending multiple exposures of a stack of images. While still having a reference exposure point for the highlight, I don't really know how to expose for the less bright part of this image since it could go down as low as total black at -14ev (considering raw) or -8ev (jpeg).

Is there such thing as the best level of exposure of shadows for exposure blending ? Thanks.

07-21-2016, 03:39 AM   #2
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This is really scene dependent - if I was unsure, i would bracket 5 shots at 1.5~2.5 stop exposure increments and figure things out in post. Hand held meters are really handy for these situations, I still use my pentax zone spot meter of situations where the in-camera spot meter isn't precise enough.

I do a lot of hand blended exposures, with a wacom graphics tablet. Pen input makes doing the required masking and blending less tedious than working with a mouse.
07-21-2016, 08:18 AM - 2 Likes   #3
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QuoteOriginally posted by biz-engineer Quote
Hi folks.
I know how critical it is to expose correctly to avoid blown high lights. In single shot technique, I expose to the right with about +2ev above mid level, for the brightest part of the frame. In this way, the full range of the sensor is used.

That said, I now play with blending multiple exposures of a stack of images. While still having a reference exposure point for the highlight, I don't really know how to expose for the less bright part of this image since it could go down as low as total black at -14ev (considering raw) or -8ev (jpeg).

Is there such thing as the best level of exposure of shadows for exposure blending ? Thanks.
The concept of ETTR is not to use the "full range" of the sensor, but to capture the greatest amount of information within the image file. A digital image file is not linear (in terms of data capture), the highlight arrays can store more data than the shadows arrays. The concept of ETTR is to save as much color information about the scene as possible, and to do that, you want to use the bigger "buckets" set aside.

(A way to test this is to look at the file size of the same scene underexposed versus overexposed. The overexposed file with be larger than the under exposed file.)

I've always understood that if you want to do exposure stacking, you would expose your darks at as close to 128,128,128 as possible, which obviously obliterates close to 50% of your image, but you don't care about that anyway since you will be layering masking those parts out.

But by pushing the shadows that high, you get a really good signal to noise ratio and a lot more color information. When you do drop the exposure levels, you are getting cleaner darks.

From Wikipedia:
"ETTR was initially espoused in 2003 by Michael Reichmann on his website, after purportedly having a discussion with software engineer Thomas Knoll, the original author of Adobe Photoshop and developer of the Camera Raw plug-in.[1] Their rationale was based on the linearity of CCD and CMOS sensors, whereby the electric charge accumulated by each subpixel is proportional to the amount of light it is exposed to (plus electronic noise). Although a camera may have a dynamic range of 5 or more stops, when image data is recorded digitally the highest (brightest) stop uses fully half of the discrete tonal values.

This is because a difference of 1 stop represents a doubling or halving of exposure. The next highest stop uses half of the remaining values, the next uses half of what is left and so on, such that the lowest stop uses only a small fraction of the tonal values available.[20][21] This may result in a loss of tonal detail in the dark areas of a photograph and posterization during post-production. By deliberately exposing to the right and then stopping down afterwards (during processing) the maximum amount of information is retained."


Disclaimer (if needed): I am a huge supporter of Luminous Landscape, and owe a lot of my knowledge base to articles from Michael Reichmann et al. It's that article referenced in 2003 that really brought into clarity for the me the difference between film and digital. Coupled with my degree in software design, it made too much sense. I have been an ETTR believer ever since.

Last edited by nomadkng; 07-21-2016 at 08:32 AM.
07-21-2016, 08:57 AM   #4
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QuoteOriginally posted by Digitalis Quote
This is really scene dependent - if I was unsure, i would bracket 5 shots at 1.5~2.5 stop exposure increments and figure things out in post.
After trying doing spot metering on both high light zone and shadows, it gets too complicated (because I need to move the camera for metering each spot), and I also don't have a standalone spot light meter. If I spot meter the high light point only and then bracket 5 shots based on a normal auto exposure , as you mention, I can play around in post... as it's more safe to have 5 shots and a comfortable display at home than trying to check for exposure on a small camera display in the field. So, yeah, that's a good advice.

07-21-2016, 09:04 AM   #5
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QuoteOriginally posted by biz-engineer Quote
After trying doing spot metering on both high light zone and shadows, it gets too complicated (because I need to move the camera for metering each spot), and I also don't have a standalone spot light meter. If I spot meter the high light point only and then bracket 5 shots based on a normal auto exposure , as you mention, I can play around in post... as it's more safe to have 5 shots and a comfortable display at home than trying to check for exposure on a small camera display in the field. So, yeah, that's a good advice.
When in doubt I just get a few more bracketed frames for a bigger DR. Usually works very well for a static subject.
07-21-2016, 09:06 AM   #6
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QuoteOriginally posted by nomadkng Quote
I've always understood that if you want to do exposure stacking, you would expose your darks at as close to 128,128,128 as possible, which obviously obliterates close to 50% of your image, but you don't care about that anyway since you will be layering masking those parts out. But by pushing the shadows that high, you get a really good signal to noise ratio and a lot more color information. When you do drop the exposure levels, you are getting cleaner darks.
Thanks, that makes sense. This mid level shot could also be bracketed , so when I blend the shots in post, I start with this as initial trial and then use a slightly different exposed shots as an option.

---------- Post added 21-07-16 at 18:16 ----------

QuoteOriginally posted by mattb123 Quote
When in doubt I just get a few more bracketed frames for a bigger DR. Usually works very well for a static subject.
Thanks. Yes, that's for landscape. I have a full gradual ND filter set but it is now too small to mount on the DFA24-70, and I did not want to buy a new set and try to use exposure fusion instead. Also, I don't like ND grad because the straight line of light attenuation seldom fit the shapes of landscapes. I found a video from B&H about exposure fusion. So, I started playing around with exposure fusion, but need to tune and get better at getting the right exposures for this workflow, I messed around a bit with trying to get systematic with exposures, so that's why I posted this thread. Thanks for sharing.
07-21-2016, 10:35 PM   #7
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QuoteOriginally posted by biz-engineer Quote
In single shot technique, I expose to the right with about +2ev above mid level, for the brightest part of the frame. In this way, the full range of the sensor is used.
A single RAW file is about all I ever use. I very rarely use bracketed shots but then I'm not shooting landscapes with a tripod.

A quick single handheld RAW snapshot before and after PP.


Last edited by wildman; 07-28-2016 at 07:17 AM.
07-22-2016, 12:20 PM   #8
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QuoteOriginally posted by wildman Quote
A single RAW file is about all I ever use. I very rarely use bracketed shots but then I'm not shooting landscapes with a tripod.

A quick single handheld RAW snapshot before and after PP.
That's typically what I do too. Expose for highlights and let DR and pp take care of the shadows unless the DR seems extreme.
07-22-2016, 02:08 PM   #9
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QuoteOriginally posted by mattb123 Quote
unless the DR seems extreme.
Which makes me wonder how much better the new FF would be for extreme DR if at all......
07-22-2016, 03:02 PM   #10
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QuoteOriginally posted by mattb123 Quote
That's typically what I do too. Expose for highlights and let DR and pp take care of the shadows unless the DR seems extreme.
I do something similar but drop half a stop down. Esp if there is a lot of sky in the shot. That, I've found, allows a lot of retention of detail in the clouds which is great when processing the RAW on the desktop. The K-5 II sensor provides a tonnn of data to push from shadows..
09-05-2016, 06:14 AM   #11
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I usually take a first shot with matrix metering, without any exposure compensation, in Av mode. Then I check the histogram and increase shutter speed until I make sure I'm not blowing up the highlights. Depends on the scene, though. Sometimes I decide I don't mind blowing up highlights if the details there are not important for the photo. Sometimes blown up highlights work well in B&W. Then in PP I push the shadows.
09-16-2016, 02:08 PM   #12
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I guess it's a bit late on this thread, but I don't worry too much about clipping highlights or the histogram. Not that it isn't important (it is), but I shoot raw and I've found in post that the histogram is for the JPEG file generated, which is generally a conservative representation of what is captured. Things that appeared clipped aren't really clipped or are easily recovered.

I do generally try to expose to the right, and I do bracket exposures when it appears I might have more dynamic range than a shot can capture, but I mostly find myself able to process one frame from the bracket to get a final result, 95% of the time.

Most of the time, when I do get highlights clipping out, they are in highly localized regions not of high importance to the image. For a good final image, I often let portions of the image clip to the high and low end to maximize contrast.
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