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Tutorial: Welcome to Raw Exposure
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Mar 25, 2016 16:56:13   #
Uuglypher Loc: South Dakota (East River)
 
Rich1939 wrote:
Dave, I believe that a light has come on in my “comprehender”. I’ve been doing my best to confuse myself by thinking old school while trying to understand new school. I am ready to proceed.:) And, I also still carry a Pentax digital spot.
BTW For those new to the world of photography, with regards to your procedures for establishing camera characteristics, working in the north side shadows of a building on a bright day obviates the need to wait for an overcast one.

thank you for your response
Rich
Dave, I believe that a light has come on in my “co... (show quote)


You are absolutely right..."open shade" works quite as well as an overcast day.

And I can easily relate to your feeling of a light coming on...I felt that when reading Bruce Fraser's Adobe white paper on Raw Exposure and Michael Ricmann's article on "Expose to the Right", and Jeff Schewe's further observations on the matter.

Reply
Sep 21, 2016 20:47:57   #
Uuglypher Loc: South Dakota (East River)
 
I received some questions from Gary Minor, re-read the tutorial, and changed some wording that could easily have been confusing.

This:

"or,
what about being able to cut your already fast shutter speed in half to permit hand-holding with a longer lens, or using a monopod instead of a tripod?"

...has been replaced with this:

with this;
"or,
what about being able to cut your already short shutter duration in half (reduce it by one full stop) to permit hand-holding with a longer lens, or using a monopod instead of a tripod?"

I have long been used to speaking of "shutter duration" rather than shutter speed, but occasionally lapse into the more common ( and occasionally confusing) phrase "shutter speed". My apologies to any who found the original sentence understandably confusing.

The text of the tutorial is being changed.

Best regards,

Dave

Reply
Sep 22, 2016 22:22:16   #
Uuglypher Loc: South Dakota (East River)
 
Gary, you wrote:
Dave, Thanks for the response.

I knew that you meant shutter duration. This was clear from the rest of the sentence.
However I think that the complete opposite is true.

You say:
EBTR allows cutting the shutter duration in half to permit hand-holding with a longer lens, or using a monopod instead of a tripod.

I say:
EBTR requires increasing the shutter duration by double, preventing hand-holding with a longer lens, or requiring using a tripod instead of a monopod"

You say:
The advantage to EBTR is that it maximizes ALL exposure options beyond those available for raw capture with a lesser dynamic range.

I say:
The disadvantage to EBTR is that it reduces ALL exposure options below those available for raw capture with a lesser dynamic range.

Thanks for the listening,
Gary

xxxxxxxxxxx

Gary,
The assertions you make are unaccompanied by the rationale upon which you base them.
In essence, you are stating that a camera with a sensor of lesser dynamic range is to be preferred to a camera with a sensor of greater dynamic range. Why not support that promise for starters..???

And be sure to relate your comments and justifications to raw capture, NOT JPEG files. It is in that connection with raw capture that EBTR becomes essential.

Dave

Reply
 
 
Sep 23, 2016 11:04:56   #
Garyminor Loc: Raleigh, NC
 
Uuglypher wrote:

Gary,
The assertions you make are unaccompanied by the rationale upon which you base them.
In essence, you are stating that a camera with a sensor of lesser dynamic range is to be preferred to a camera with a sensor of greater dynamic range. Why not support that promise for starters..???

And be sure to relate your comments and justifications to raw capture, NOT JPEG files. It is in that connection with raw capture that EBTR becomes essential.

Dave


Dave,

Without a doubt, the best quality comes from exposing as far to the right as you can, without exceeding the capabilities of the sensor.
Certainly, I would prefer a camera with a sensor of large dynamic range.
I'm simply pointing out that it is not always best to use all of that dynamic range, depending on the scene and the objectives.
It may be more important to have larger depth of focus, or shorter shutter duration, rather than a higher quality image.

I also understand that if the brightest highlights fall one stop less than the highest available from the sensor, then 50% of the possible sensor values are going unused.

My assertion is that when you expose beyond the right, you incur the cost of longer shutter duration or larger aperture.

Here is my rationale.

Start with a normally exposed, sunny day scene, ISO 100, 1/100 sec shutter, f/16 aperture, using a 200mm lens.
In this case, it would be difficult to hand-hold the 200 mm lens, but a monopod would probably be OK.

If instead, you expose beyond the right, then according to the tutorial, the shutter duration would become 1/200 and you would be able to hand-hold a 200mm lens.
It seems to me that this is incorrect.

What actually happens is that the shutter duration becomes 1/50 sec, and a tripod is required. This is exactly opposite of what is stated in the tutorial.

Note 1: My comments and justifications are related to raw capture.

Note2: This is not an expression of my opinion of when to use EBTR. Each user must evaluate the benefits and cost, depending on the objectives.

Thanks,
Gary

Reply
Sep 23, 2016 12:24:54   #
Uuglypher Loc: South Dakota (East River)
 
Garyminor wrote:
Dave,

Without a doubt, the best quality comes from exposing as far to the right as you can, without exceeding the capabilities of the sensor.
Certainly, I would prefer a camera with a sensor of large dynamic range.
I'm simply pointing out that it is not always best to use all of that dynamic range, depending on the scene and the objectives.
It may be more important to have larger depth of focus, or shorter shutter duration, rather than a higher quality image.

I also understand that if the brightest highlights fall one stop less than the highest available from the sensor, then 50% of the possible sensor values are going unused.

My assertion is that when you expose beyond the right, you incur the cost of longer shutter duration or larger aperture.

Here is my rationale.

Start with a normally exposed, sunny day scene, ISO 100, 1/100 sec shutter, f/16 aperture, using a 200mm lens.
In this case, it would be difficult to hand-hold the 200 mm lens, but a monopod would probably be OK.

If instead, you expose beyond the right, then according to the tutorial, the shutter duration would become 1/200 and you would be able to hand-hold a 200mm lens.
It seems to me that this is incorrect.

What actually happens is that the shutter duration becomes 1/50 sec, and a tripod is required. This is exactly opposite of what is stated in the tutorial.

Note 1: My comments and justifications are related to raw capture.

Note2: This is not an expression of my opinion of when to use EBTR. Each user must evaluate the benefits and cost, depending on the objectives.

Thanks,
Gary
Dave, br br Without a doubt, the best quality com... (show quote)


Gary,
Your premise is incorrect.
When you use the "Sunny-F/16" rule you are using the accepted and very useful rule for exposing film and JPEG files.....
NOT for exposing for optimal raw image data capture.

Raw capture is a totally different imaging medium from film and JPEG files.

There is no "down side" to an appropriately exposed raw capture. If you need to stop motion, use an ultra-short shutter duration; if you need a shallow DOF , use a large aperture, if you need....well...you get the idea. The image seen in your camera's display will be washed-out with blown highlights...which is what you WOULD have captured IF you had shot a JPEG file. But when you download that SOOC raw file into your raw converter and tonally normalize it by sliding the Exposure slider to the left, you'll find the image you visualized capturing.

You really have to give it an honest try, Gary, before you can begin to understand its merits. And having captured an appropriately exposed raw capture, you'll find that image file has amazing creative versatility from high-to low-key approaches and imaginative manipulations of tonal and color range and spectra.

And finally, the decision as to whether or not to use EBTR is, of course, up to the photographer. From my perspective, if capturing raw image data, EBTR is always the exposure tactic of choice; however, if JPEG capture is to be used ... for example when it it must be under some circumstances...such as some burst exposure modes for B.I.F.s ...then the traditional film/JPEG exposure strategies that I've used since the late 1940s become the comfortable recourse.


It's all based upon and derived from what I consider to be the basic Canon of Digital Exposure Knowledge:

Reichmann, Michael, essay in Luminous Landscape, 2003
"Expose Right"
http://www.luminous-landscape.com/tutorials/expose-right.shtml
...and a follow-up in 2011:"Optimizing Exposure"
http://www.luminous-landscape.com/tutorials/optimizing_exposure.shtml

Fraser, Bruce,
"RAW Capture, Linear Gamma, and Exposure"Adobe White Paper, 2004,
http://www.adobe.com/digitalimag/pdfs/linear_gamma.pdf

Fraser, Bruce, and Jeff Schewe, "Real World Camera RAW.
Peachpit Press, 20O9,

Schewe, Jeff, "The Digital Negative", Peachpit Press, 2013

Schewe, Jeff, "The Digital Print" , Peachpit Press, 2014


I can't remember if I've posted these graphics in our discussions, but if I have...redundancy has its merits.

Best regards,

Dave


(Download)


(Download)

Reply
Sep 23, 2016 13:29:43   #
rmalarz Loc: Tempe, Arizona
 
Just to add a couple of examples, inspired by Dave's posts of a while back, here is one I did when starting to use the ETTR/EBTR approach. I view this technique as a reverse of The Zone System, wherein I set my exposure for the highlights of the scene and process for the shadows.

Dave, I hope you don't mind my posting a photo illustrating the premise of your post.
--Bob



Uuglypher wrote:
A Tutorial for Newcomers to Raw Capture

Now That You've Decided to Capture Raw Image Data Rather than JPEG Files
You will learn:
That Your camera has more dynamic range available for improved image quality with
Raw image data capture with less noise than was available for JPEG file capture.

How to determine how much extra dynamic range your camera has for Raw exposure.

How to use that extra dynamic range

xxxxxxxxxxxxxxccccc

If you have just begun to capture raw image files it will be to your advantage to realize that if you are still using your camera's "highlight clipping warning" ...the "blinkies"... you are letting your camera lie like a used car dealer! Those so-called "clipping" warnings are accurate only for an 8-Bit JPEG image file extracted from the 12-bit or 14-bit raw image data you are now capturing as Raw image files.The JPEG-adjusted thumbnail image and histogram do not reflect the
Extra Raw-accessible Dynamic Range (ERADR) your camera possesses.

Your Camera Has Extra Dynamic Range For Use with RAW
(but not with JPEG files)
Every one of the 30-plus digital cameras I've tested so far (by examination of properly prepared ERADR Evaluation Exposure Series) has had at least 1/3 stop to over three stops of Exposure Value (E.V.s) beyond the clipping exposure indicated by the on-board histogram! That's a lot of available exposure to leave "sitting on the table" ignored and unused! So experiment (as described below) and find out how much extra raw-accessible dynamic range (ERADR) your camera actually has!

And if you really need another reason to use that extra dynamic range it is that you can capture your image data considerably farther "to the Right"...actually "Beyond the Right" (of the histogram frame) than before. "So what?" I hear you cry! Well, in so doing, you avoid the capture of most of the noise you used to capture in the darker, shadowy left end of the histogram frame...also known as the home of the "Mother Lode of Noise"

How much Extra Dynamic Range
Does Your Camera Have for Raw Exposure?

Here's the easiest way to get a handle on how much extra raw-accessible dynamic range (ERADR) your particular camera has at base ISO. On a somewhat overcast day (soft-edged shadows) find a scene with a dynamic range less than that of your sensor. In other words, a scene that produces a histogram that falls completely within your camera's histogram frame with no clipped shadows at the left (dark) end or clipped highlights at the right (bright) end.. Set the camera to its native ISO (usually ISO 100...or ISO 200 if you usually use that as the low end) Attach your camera to a sturdy tripod or other solid support. Then increase the exposure with progressively larger apertures (smaller F-Numbers) until the extreme right end of the "light pile" just barely "kisses" the right side of the histogram frame without triggering the highlight clipping warning "blinkies". Now, by increasing each subsequent exposure by 1/3 stop of shutter speed, add four full stops of exposure (that's twelve exposures, each 1/3 stop longer in shutter duration than the previous one).

Download the image files into your raw converter. Open each exposure and tonally normalize it by left-sliding the "Exposure" slider. As each "washed out, too bright" image is tonally normalized, you'll see the histogram slide left and fully into the histogram frame. Do this in sequence until you find the histogram that contains a "spike" at the right end of the light pile that indicates blown highlight detail. Just a caution here... if the scene contained some specular highlights, then a very thin, one-pixel wide spike is permissible. If you see such a "specular highlight spike", go ahead and open the next frame, which will have a substantial spike of blown/clipped highlights at the right end of the light pile.

The first three images below are from a series made to determine the amount of ERADR at ISO 200.

First is the ETTR exposure. (1/200 sec) It is SOOC. Note that it has not been tonally normalized; its exposure has not been changed from default settings and the right end of the histogram comes as close as possible to the right side of the histogram frame without tripping highlight clipping warning.

The next image shown (1/80 sec) is, counting the ETTR Image, the fifth in the series. It has been tonally normalized and is the last exposure in the series that did NOT reveal highlight clipping after normalization.
.
The third, (1/60 sec) also tonally normalized, is the next in the test sequence and demonstrates the sharp "spike" of clipped highlights at the right end of its "light pile", even though tonally normalized as well as possible!

1/200 (ETTR)
1/ 170
1/130
1/100
1:80 (last EBTR exposure without highlight clipping)
1/60 (first EBTR exposure showing blown / clipped highlights)

ERADR = Four exposures = one and 1/3 stops !


The number of exposures between your brightest possible JPEG exposure (the ETTR exposure) and the first exposure with actual blown highlights( not just specular highlights) constitutes your camera's ERADR (Extra Raw-Accessible Dynamic Range).
1 exposure? 1/3 stop
2 exposures? 2/3 stop
3 exposures? one full stop.
4 exposures? one and 1/3 stops (as illustrated in the case discussed above)
5 exposures? one and 2/3 stops
6 exposures? two full stops
7 exposures? two and 1/3 stops
8 exposures? two and 2/3 stops
9 exposures? three full stops
10 exposures? three and 1/3 stops
11 exposures? three and 2/3 stops (not seen one of these yet...!!!!)
12 exposures? four full stops (not seen one of these yet ...!!!!!)


Caveat:
You should test your camera's ERADR
at the ISOs you most commonly Use

As ISO increases, the camera's amount of ERADR gradually and irregularly decreases. As an example, I've a camera that, at ISO 100 has one and 1/3 Stops of ERADR. At ISO 400 it drops to one full stop, and at ISO 3200 the ERADR is 2/3 stop.

Why don't I just compile a list of camera brands and models and state the tested ERADR of each? Because three camera's of the same make and model can have three different amounts of ERADR at a given ISO! So, I'm sorry...but you just gotta test each individual camera!


How to Use that Extra Dynamic Range

So, how do you actually use that ERADR once determined? Set your exposure as for a JPEG file using your camera's meter, a hand-held reflective, spot-reading, or incident light meter. Enter the exposure into your camera, and, adjust that exposure so that the right end of the "light pile" of the histogram moves right to barely kiss the right side of the histogram frame juuuuuust before clipping the highlights clipping warning/the "blinkies". It doesn't matter if the the right end of the light pile is a sizeable "lump" or a just a slender white line extending along the frame's base. When it just barely touches the right side of the frame. THAT is the ETTR exposure -your starting point. THEN.... add your known stops of ERADR using either slower shutter speeds or larger apertures (or a combination) and make your exposure. Note: Most who regularly use EBTR normally use 1/3 stop less than their established ERADR ,just to " play it safe" as regards possibly clipping highlights. Why "play it safe"? Because in many camera's there is often some inaccuracy in tripping the "blinkies".

REMEMBER:
When you start using that extra dynamic range, realize that your camera's LCD display of the viewed thumbnail will, with most scenes, likely appear "washed out" with "blown highlights" (because it "thinks" it is displaying an "overexposed" JPEG file instead of a correctly exposed raw image file. So... DO NOT INTERPRET SUCH WASHED-OUT IMAGES AS "OVEREXPOSED"!!! THEY ARE CORRECTLY EXPOSED RAW IMAGE DATA FILES !!!
Download the files into your computer's raw converter (Adobe Camera Raw is fine), move the "Exposure" slider to the left, and you'll see the image become tonally normalized with its full, expected tonal range and tonal spectrum! When you are new to EBTR, every time you tonally normalize a washed-out image, it's like a miracle to watch that tonally perfect image appear right before your eyes! It sort of reminds me of watching an image appear in a print in the developing tray under the dim green safelight in my dad's darkroom in the late 1940s.

"So what's the big deal about a measly Stop?

It is at about this point in a class or workshop that some back-row sitter pipes up with:
"C'mon, Dave, are you really telling me that just one measly stop is really worth all this trouble?"
So I ask him, "What's your best, fastest lens?

"Er...100mm., f/1.4, why?"

"we'll, would you mind if I took your lens and superglued it so it it couldn't open up beyond f/2 ?"

or....

"What if you couldn't, simply by increasing raw exposure by one stop, significantly reduce the amount of noise you routinely capture?"

or

"Think of the times that limited illumination have made you wish for "just one more "measly" stop?"

or,

what about being able to cut your already short shutter duration in half ( reduce it by one full stop) to permit hand-holding with a longer lens, or using a monopod instead of a tripod?

Yeah, I'd say there's considerable advantage to getting every bit of extra dynamic range as you can out of that sensor that amounted to 2/3 of the cost of that new camera body you just bought!

Here we're talking about pulling out, at the very least, 2/3 stop of exposure up to possibly more than three stops of exposure beyond what your camera's lying JPEG-adjusted histogram suggests you can actually use!
'Tain't chicken feed, McGee!
"One measly stop of exposure? I wouldn't give that up, as we said back in college, "...for love nor money"'

Below (lower than the three exposures from the ERADR test series) are some examples of SOOC (straight out of camera) and post-tonal normalization images. The abbreviation "EBTR" used in the images refers to "Expose Beyond the Right" - the technique of utilizing that extra dynamic range your camera has when you are exposing for and capturing Raw image data files.

Welcome to the wonderful world of Raw image data capture. Learn to use all of your your camera's dynamic range. It's obviously well worth the effort.

Dave Graham
Windswaard
East River, SD
davidleegraham.biz
A Tutorial for Newcomers to Raw Capture br br Now... (show quote)

SOOC
SOOC...
(Download)

Processed
Processed...
(Download)

Reply
Sep 23, 2016 14:31:16   #
Uuglypher Loc: South Dakota (East River)
 
rmalarz wrote:
Just to add a couple of examples, inspired by Dave's posts of a while back, here is one I did when starting to use the ETTR/EBTR approach. I view this technique as a reverse of The Zone System, wherein I set my exposure for the highlights of the scene and process for the shadows.

Dave, I hope you don't mind my posting a photo illustrating the premise of your post.
--Bob


Not at all, Bob.
your SOOC and post-tonal normalization images are good additional examples of result of proper raw exposure, the typical appearance of the washed-out image in the thumbnail of the camera's display, and the definitive evidence of the tonally replete, final, post-processed image.

Gary's questions stimulate valuable discussion because they are of the sort commonly heard from those inexperienced with proper raw exposure, pointing out what a different medium raw image data is from both film and the JPEG image file.

Nice examples, Bob; thanks.

Dave

Reply
 
 
Sep 23, 2016 18:12:05   #
Garyminor Loc: Raleigh, NC
 
Dave,

Thanks for the links. I have read, understood, and agree with all of them. I also agree with most of your tutorial where you describe the benefits of EBTR.

The primary concern is your assertion that EBTR allows cutting the shutter duration in half to permit hand-holding with a longer lens, or using a monopod instead of a tripod.
Can you give me an example of that, using numerical values for shutter duration and lens focal length?

Gary

Reply
Sep 24, 2016 06:03:38   #
Uuglypher Loc: South Dakota (East River)
 
Garyminor wrote:
Dave,

Thanks for the links. I have read, understood, and agree with all of them. I also agree with most of your tutorial where you describe the benefits of EBTR.

The primary concern is your assertion that EBTR allows cutting the shutter duration in half to permit hand-holding with a longer lens, or using a monopod instead of a tripod.
Can you give me an example of that, using numerical values for shutter duration and lens focal length?

Gary


Well Hi there, Gary,
I was just settling in to read your latest installment and see that you've put a rubric tint on reference to the passage that seems to bothe....Oh...My...Gawd! ...that passage I wrote makes NO ... SENSE ...AT ...ALL!

FUDGE!

Sheesh...!!!

At this very moment I envision the "...big brown truck..." pulling into my driveway to deliver what could only be my trophy for having exceeded all previously known records for, and examples of a ridiculously extended duration of blyth obliviousness to such a weird and non-sensical, illogical gaffe! I have to wonder if an entry, in my name, has been submitted for next year's contest. (My wife says it's likely!)

And I suspect that a brown truck is also on its way to you, Gary, bearing a richly deserved award for polite consideration in abjuring use of such terms as " stupid idjit" and "ignorant dolt" in the course of trying to draw my attention, politely, to the ludicrousitude* of my lapse of logic.

Thank you, Gary; you are, indeed, a gentleman and a credit to those who raised you! I can think of a few who would delight in pilloring someone for such a blatant error.

So let's keep this just among the two of us....O.K.?

Best regards to a patient gentleman,

Dave

*A neologism a day keeps the riff-raff away!

Reply
Sep 24, 2016 10:39:59   #
Garyminor Loc: Raleigh, NC
 
Uuglypher wrote:
Well Hi there, Gary,
I was just settling in to read your latest installment and see that you've put a rubric tint on reference to the passage that seems to bothe....Oh...My...Gawd! ...that passage I wrote makes NO ... SENSE ...AT ...ALL!

FUDGE!

Sheesh...!!!

At this very moment I envision the "...big brown truck..." pulling into my driveway to deliver what could only be my trophy for having exceeded all previously known records for, and examples of a ridiculously extended duration of blyth obliviousness to such a weird and non-sensical, illogical gaffe! I have to wonder if an entry, in my name, has been submitted for next year's contest. (My wife says it's likely!)

And I suspect that a brown truck is also on its way to you, Gary, bearing a richly deserved award for polite consideration in abjuring use of such terms as " stupid idjit" and "ignorant dolt" in the course of trying to draw my attention, politely, to the ludicrousitude* of my lapse of logic.

Thank you, Gary; you are, indeed, a gentleman and a credit to those who raised you! I can think of a few who would delight in pilloring someone for such a blatant error.

So let's keep this just among the two of us....O.K.?

Best regards to a patient gentleman,

Dave

*A neologism a day keeps the riff-raff away!
Well Hi there, Gary, br I was just settling in to ... (show quote)


Dave,

Thanks for your very gracious response. That makes it all worthwhile.

A new friend,
Gary

Reply
Oct 31, 2016 09:30:11   #
MtnMan Loc: ID
 
Uuglypher wrote:
A Tutorial for Newcomers to Raw Capture

Now That You've Decided to Capture Raw Image Data Rather than JPEG Files
You will learn:
That Your camera has more dynamic range available for improved image quality with
Raw image data capture with less noise than was available for JPEG file capture.

How to determine how much extra dynamic range your camera has for Raw exposure.

How to use that extra dynamic range

xxxxxxxxxxxxxxccccc

If you have just begun to capture raw image files it will be to your advantage to realize that if you are still using your camera's "highlight clipping warning" ...the "blinkies"... you are letting your camera lie like a used car dealer! Those so-called "clipping" warnings are accurate only for an 8-Bit JPEG image file extracted from the 12-bit or 14-bit raw image data you are now capturing as Raw image files.The JPEG-adjusted thumbnail image and histogram do not reflect the
Extra Raw-accessible Dynamic Range (ERADR) your camera possesses.

Your Camera Has Extra Dynamic Range For Use with RAW
(but not with JPEG files)
Every one of the 30-plus digital cameras I've tested so far (by examination of properly prepared ERADR Evaluation Exposure Series) has had at least 1/3 stop to over three stops of Exposure Value (E.V.s) beyond the clipping exposure indicated by the on-board histogram! That's a lot of available exposure to leave "sitting on the table" ignored and unused! So experiment (as described below) and find out how much extra raw-accessible dynamic range (ERADR) your camera actually has!

And if you really need another reason to use that extra dynamic range it is that you can capture your image data considerably farther "to the Right"...actually "Beyond the Right" (of the histogram frame) than before. "So what?" I hear you cry! Well, in so doing, you avoid the capture of most of the noise you used to capture in the darker, shadowy left end of the histogram frame...also known as the home of the "Mother Lode of Noise"

How much Extra Dynamic Range
Does Your Camera Have for Raw Exposure?

Here's the easiest way to get a handle on how much extra raw-accessible dynamic range (ERADR) your particular camera has at base ISO. On a somewhat overcast day (soft-edged shadows) find a scene with a dynamic range less than that of your sensor. In other words, a scene that produces a histogram that falls completely within your camera's histogram frame with no clipped shadows at the left (dark) end or clipped highlights at the right (bright) end.. Set the camera to its native ISO (usually ISO 100...or ISO 200 if you usually use that as the low end) Attach your camera to a sturdy tripod or other solid support. Then increase the exposure with progressively larger apertures (smaller F-Numbers) until the extreme right end of the "light pile" just barely "kisses" the right side of the histogram frame without triggering the highlight clipping warning "blinkies". Now, by increasing each subsequent exposure by 1/3 stop of shutter speed, add four full stops of exposure (that's twelve exposures, each 1/3 stop longer in shutter duration than the previous one).

Download the image files into your raw converter. Open each exposure and tonally normalize it by left-sliding the "Exposure" slider. As each "washed out, too bright" image is tonally normalized, you'll see the histogram slide left and fully into the histogram frame. Do this in sequence until you find the histogram that contains a "spike" at the right end of the light pile that indicates blown highlight detail. Just a caution here... if the scene contained some specular highlights, then a very thin, one-pixel wide spike is permissible. If you see such a "specular highlight spike", go ahead and open the next frame, which will have a substantial spike of blown/clipped highlights at the right end of the light pile.

The first three images below are from a series made to determine the amount of ERADR at ISO 200.

First is the ETTR exposure. (1/200 sec) It is SOOC. Note that it has not been tonally normalized; its exposure has not been changed from default settings and the right end of the histogram comes as close as possible to the right side of the histogram frame without tripping highlight clipping warning.

The next image shown (1/80 sec) is, counting the ETTR Image, the fifth in the series. It has been tonally normalized and is the last exposure in the series that did NOT reveal highlight clipping after normalization.
.
The third, (1/60 sec) also tonally normalized, is the next in the test sequence and demonstrates the sharp "spike" of clipped highlights at the right end of its "light pile", even though tonally normalized as well as possible!

1/200 (ETTR)
1/ 170
1/130
1/100
1:80 (last EBTR exposure without highlight clipping)
1/60 (first EBTR exposure showing blown / clipped highlights)

ERADR = Four exposures = one and 1/3 stops !


The number of exposures between your brightest possible JPEG exposure (the ETTR exposure) and the first exposure with actual blown highlights( not just specular highlights) constitutes your camera's ERADR (Extra Raw-Accessible Dynamic Range).
1 exposure? 1/3 stop
2 exposures? 2/3 stop
3 exposures? one full stop.
4 exposures? one and 1/3 stops (as illustrated in the case discussed above)
5 exposures? one and 2/3 stops
6 exposures? two full stops
7 exposures? two and 1/3 stops
8 exposures? two and 2/3 stops
9 exposures? three full stops
10 exposures? three and 1/3 stops
11 exposures? three and 2/3 stops (not seen one of these yet...!!!!)
12 exposures? four full stops (not seen one of these yet ...!!!!!)


Caveat:
You should test your camera's ERADR
at the ISOs you most commonly Use

As ISO increases, the camera's amount of ERADR gradually and irregularly decreases. As an example, I've a camera that, at ISO 100 has one and 1/3 Stops of ERADR. At ISO 400 it drops to one full stop, and at ISO 3200 the ERADR is 2/3 stop.

Why don't I just compile a list of camera brands and models and state the tested ERADR of each? Because three camera's of the same make and model can have three different amounts of ERADR at a given ISO! So, I'm sorry...but you just gotta test each individual camera!


How to Use that Extra Dynamic Range

So, how do you actually use that ERADR once determined? Set your exposure as for a JPEG file using your camera's meter, a hand-held reflective, spot-reading, or incident light meter. Enter the exposure into your camera, and, adjust that exposure so that the right end of the "light pile" of the histogram moves right to barely kiss the right side of the histogram frame juuuuuust before clipping the highlights clipping warning/the "blinkies". It doesn't matter if the the right end of the light pile is a sizeable "lump" or a just a slender white line extending along the frame's base. When it just barely touches the right side of the frame. THAT is the ETTR exposure -your starting point. THEN.... add your known stops of ERADR using either slower shutter speeds or larger apertures (or a combination) and make your exposure. Note: Most who regularly use EBTR normally use 1/3 stop less than their established ERADR ,just to " play it safe" as regards possibly clipping highlights. Why "play it safe"? Because in many camera's there is often some inaccuracy in tripping the "blinkies".

REMEMBER:
When you start using that extra dynamic range, realize that your camera's LCD display of the viewed thumbnail will, with most scenes, likely appear "washed out" with "blown highlights" (because it "thinks" it is displaying an "overexposed" JPEG file instead of a correctly exposed raw image file. So... DO NOT INTERPRET SUCH WASHED-OUT IMAGES AS "OVEREXPOSED"!!! THEY ARE CORRECTLY EXPOSED RAW IMAGE DATA FILES !!!
Download the files into your computer's raw converter (Adobe Camera Raw is fine), move the "Exposure" slider to the left, and you'll see the image become tonally normalized with its full, expected tonal range and tonal spectrum! When you are new to EBTR, every time you tonally normalize a washed-out image, it's like a miracle to watch that tonally perfect image appear right before your eyes! It sort of reminds me of watching an image appear in a print in the developing tray under the dim green safelight in my dad's darkroom in the late 1940s.

"So what's the big deal about a measly Stop?

It is at about this point in a class or workshop that some back-row sitter pipes up with:
"C'mon, Dave, are you really telling me that just one measly stop is really worth all this trouble?"
So I ask him, "What's your best, fastest lens?

"Er...100mm., f/1.4, why?"

"we'll, would you mind if I took your lens and superglued it so it it couldn't open up beyond f/2 ?"

or....

"What if you couldn't, simply by increasing raw exposure by one stop, significantly reduce the amount of noise you routinely capture?"

or

"Think of the times that limited illumination have made you wish for "just one more "measly" stop?"

Yeah, I'd say there's considerable advantage to getting every bit of extra dynamic range as you can out of that sensor that amounted to 2/3 of the cost of that new camera body you just bought!

Here we're talking about pulling out, at the very least, 2/3 stop of exposure up to possibly more than three stops of exposure beyond what your camera's lying JPEG-adjusted histogram suggests you can actually use!
'Tain't chicken feed, McGee!
"One measly stop of exposure? I wouldn't give that up, as we said back in college, "...for love nor money"'

Below (lower than the three exposures from the ERADR test series) are some examples of SOOC (straight out of camera) and post-tonal normalization images. The abbreviation "EBTR" used in the images refers to "Expose Beyond the Right" - the technique of utilizing that extra dynamic range your camera has when you are exposing for and capturing Raw image data files.

Welcome to the wonderful world of Raw image data capture. Learn to use all of your your camera's dynamic range. It's obviously well worth the effort.

Dave Graham
Windswaard
East River, SD
davidleegraham.biz
A Tutorial for Newcomers to Raw Capture br br Now... (show quote)


Thanks for a great tutorial I just found. A few questions:

1. Is your first image the one intended? The white looks more blown than the one just below at allegedly higher shutter speed (less exposure).

2. The text talked to changing aperture for the test but your examples change shutter speed. Please clarify.

3. The last exchange suggests you agree that decreasing shutter speed isn't going to create sharper images with longer lenses. Did I get that right?

Thanks

Reply
 
 
Oct 31, 2016 09:33:10   #
MtnMan Loc: ID
 
MtnMan wrote:
Thanks for a great tutorial I just found. A few questions:

1. Is your first image the one intended? The white looks more blown than the one just below at allegedly higher shutter speed (less exposure).

2. The text talked to changing aperture for the test but your examples change shutter speed. Please clarify.

3. The last exchange suggests you agree that decreasing shutter speed isn't going to create sharper images with longer lenses. Did I get that right?

Thanks


Ah. Rereading answered the first question. You increase aperture to get to the starting point for the test. Got it.

Reply
Nov 22, 2016 10:01:30   #
runakid Loc: Shelbyville, TN
 
What is a RAW converter? Sorry, but I don't know.

Reply
Nov 22, 2016 10:13:46   #
minniev Loc: MIssissippi
 
runakid wrote:
What is a RAW converter? Sorry, but I don't know.


Any software that converts the raw data you upload from your camera or card to an image you can see and edit. Lightroom, Adobe Camera Raw, the software that came packaged with your camera, and many others. Here's a link to an article about what these folks consider some of the better ones - http://www.whatdigitalcamera.com/roundup/accessory-roundup/best-raw-photo-editing-software-11150.

Feel free to ask more as you go, we are pretty friendly folks on this section!

Reply
Nov 23, 2016 11:56:15   #
Uuglypher Loc: South Dakota (East River)
 
MtnMan wrote:
Ah. Rereading answered the first question. You increase aperture to get to the starting point for the test. Got it.


Hi, runakid,
A raw converter is a software application that is necessary for decoding of the raw data captured by your particular camera model, and permits its processing in a linear and non-destructive manner. The software disc that came with your camera contains raw converter software specifically for the proprietary raw data captured by that brand and model camera. There are also raw converters that are updated as new camera models are released. Each update allows converting and processing of raw capture data by many (essentially all...) camera models available as of the date of issue of the latest version of the converter. If you are using Photoshop or PS Elements the raw converter is Adobe Camera Raw (A.C.R.), the best known and generally considered the most versatile of available raw converters. Photoshop Lightroom is based on ACR and thus also provides linear (non-destructive) processing.
Is that too much or not enough info.?
Was it adequately useful?

Dave

Reply
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