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Author Topic: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.  (Read 13347 times)

TonyW

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #100 on: December 23, 2018, 02:02:06 pm »


Most of the best magazine covers for Outdoor Photographer and other magazines of the era were shot with velvia or other chrome film.    Somehow they lived with the five to seven stops that chome film gave them. Another one or two stops isn't going to make the picture. Let's not get carried away with the power of ETTR.
It really is not a question of how many stops DR you have at your disposal it is really a matter of exposing correctly to get the best out of the medium taking into account its limitations - in this case digital. 

You shot transparency or negative stock and you must have tried to expose correctly e.g. exposure to make sure you did not loose highlight detail (IF highlight detail was the most important factor of a particular shot) in transparency and maybe you exposed for the shadows developed for the highlights with B&W stock. 

You are doing no more when trying for an optimal exposure with digital to make the most of the data you have available.  You can make it as complex as you want or make it very simple. 

Simple maybe to find out how many stops you have before sensor saturation - practical testing - meter an important highlight (not specular - that should be blown) and see how many stops you have before that particular highlight gone.  I suspect most systems will not allow you more than 3 stops before clipping equating to your system being calibrated to expect 12.5% grey under the metered ROI.  It may be more or less but needs testing, again either very simple or in more detail with something like Rawdigger

DR is only part of the story and will not really change clipping limits of around 3 stops for highlights (a generalization for most systems!) so 6 stops or 14 stops DR does not change.   
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Guillermo Luijk

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #101 on: December 23, 2018, 02:12:01 pm »

I suspect most systems will not allow you more than 3 stops before clipping equating to your system being calibrated to expect 12.5% grey under the metered ROI.  It may be more or less but needs testing, again either very simple or in more detail with something like Rawdigger

Spot metering against a flat surface under tungsten lighting:

Canon 350D:


Canon 5D:


Regards

Alan Klein

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #102 on: December 23, 2018, 03:07:29 pm »

Now, come on Alan! Technical and artistic issues are different. The OP brought up a technical issue, so let's stick with that. Whether or not this issue is important to you is for you to decide....

...

Fair enough,  Frans.  I suppose I'm trying to remind myself that my issue with taking better shots is not technical on the margins,  but rather in the area of content,  overall lighting and other aesthetic areas.

Aram Hăvărneanu

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #103 on: January 31, 2019, 06:16:49 am »

Most of the best magazine covers for Outdoor Photographer and other magazines of the era were shot with velvia or other chrome film.    Somehow they lived with the five to seven stops that chome film gave them. Another one or two stops isn't going to make the picture. Let's not get carried away with the power of ETTR.

Totally bad example, ETTR is far more critical with slide film (and other low dynamic range mediums) than it is with digital. All those Outdoor Photographer shots were properly exposed (ETTR).
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Dave Rosser

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #104 on: January 31, 2019, 08:20:38 am »

To repeat what has already been said some people do like to make things difficult (and this is someone who has those green NEFs from experimenting with UniWB speaking  :( ). I just went back to square one and took a shot using the device shown in the first picture to estimate required exposure (its a simple calculator to make using B.S.935/1957 exposure tables a bit easier).
The second picture is the resulting shot of the road outside my house.  The only difficulty is deciding on weather conditions - I chose cloudy dull and the histogram in Capture One shows the exposure was spot on.  ;D

Dave




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Alan Klein

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #105 on: January 31, 2019, 08:37:11 am »

Totally bad example, ETTR is far more critical with slide film (and other low dynamic range mediums) than it is with digital. All those Outdoor Photographer shots were properly exposed (ETTR).

Actually when shooting chromes, pros often underexposed 1/3 of a stop to avoid clipping the highlights.  ETTR, even if one could make a film comparison to digital, would have caused more throwaways due to blown highlights. Underexposing also tends to saturate the colors adding even more "pop" to the already saturated Velvia. 

digitaldog

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #106 on: January 31, 2019, 09:25:11 am »

Actually when shooting chromes, pros often underexposed 1/3 of a stop to avoid clipping the highlights.  ETTR, even if one could make a film comparison to digital, would have caused more throwaways due to blown highlights. Underexposing also tends to saturate the colors adding even more "pop" to the already saturated Velvia.
No, we pros didn't because clipping highlights we didn't want to clip is over exposing!
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Alan Klein

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #107 on: January 31, 2019, 10:01:25 am »

Of course you want to get exposure exactly right.  But metering is not always an exact science.  If the photographer is concerned that he might blow the highlights and ruin the shot, he'd play it cautious and shoot 1/3 or 1/2 of a stop slower.  There were no histograms back then.  Certainly nothing where you could ETTR which has no point with film in any case.

Alan Klein

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #108 on: January 31, 2019, 10:01:58 am »

Sorry faster.

Aram Hăvărneanu

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #109 on: January 31, 2019, 10:10:57 am »

ETTR, even if one could make a film comparison to digital, would have caused more throwaways due to blown highlights.

ETTR by definition can't blow highlights. If you have (unintentional) blown highlights, you didn't do ETTR. Perhaps you attempted to do ETTR and failed.

Of course you want to get exposure exactly right.  But metering is not always an exact science.  If the photographer is concerned that he might blow the highlights and ruin the shot, he'd play it cautious and shoot 1/3 or 1/2 of a stop slower. 

Yes, but that's the same for chromes and digital.

There were no histograms back then.  Certainly nothing where you could ETTR which has no point with film in any case.

You don't need histograms to do ETTR. You only need a reflective spot meter and the film characteristic curve.

When I shoot velvia I meter the important highlights and place them at +2, knowing that +2 will still retain detail. +2.5 is pure white. I get proper exposure every time. Other slide film might have different limits.

When I shoot negative film I put important shadows at -1.5. Ansel Adams used zone III, which is -2, but I think -1.5 or even -1 is better today. Modern film has plenty dynamic range even if you put shadows at zone IV, and it's easier to control contrast digitally (Ansel benefited from a contrast boost using the toe of the transfer curve, no such need today, using the linear part of the curve is better).
« Last Edit: January 31, 2019, 10:25:41 am by Aram Hăvărneanu »
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digitaldog

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #110 on: January 31, 2019, 10:58:24 am »

Of course you want to get exposure exactly right.  But metering is not always an exact science.  If the photographer is concerned that he might blow the highlights and ruin the shot, he'd play it cautious and shoot 1/3 or 1/2 of a stop slower.  There were no histograms back then.  Certainly nothing where you could ETTR which has no point with film in any case.
Alan, your comments indicate to me you are not familiar how we professional photographers exposed E6 film. In my case, shooting national ads, magazines, annual reports etc, on E6 film for a living.
IF you haven't experienced it, you've only imagined it. Or misunderstood it.  ;)


We professional photographers purchased very large quantities of the same film emulsion (bricks and bricks), stored them in dedicated refrigerators. We'd run exposure and processing tests on the first roll. Call out and thanks to the legendary Ish of A&I color for assisting in advising us on CC filters for color balance under our strobes when testing the film and processing for that task. Every time we started a new batch of film.
We understood how our tools worked, including light meters: incident, spot or otherwise and when the meters were fooled (the old white dog on snow/black cat on coal analogy AGAIN).
Old saying from actual pro's: Don't learn the tricks of the trade, learn the trade!

We pros cloud therefore more often than not, NAIL exposure within a 1/4 a stop. That wasn't good enough! Shooting Med format, we'd dedicate an A12 back as a test role for each setup, run (process at the same lab) that then again, show it to Ish and there's the ability to finely control push/pull processing FOR EACH subsequent labelled roll in a setup for dead nuts results for reproduction! Thats what we pro's did to make the bucks shooting on E6 film. Of run what's called a snip test again to nail the processed film that was exposed within 1/4 stop or less in the first place (indeed, Ish could process film 1/8 a stop +/- and do so, day in and day out).


We know where we wanted highlights to fall. NO! We didn't under expose 1/3 a stop. We exposed OPTIMALLY for those highlights. Despite what a pretty dumb device (a light meter) suggests.
That's at least how I was professionally trained to expose E6 film and how I exposed E6 film (among other kinds of film) professionally; my day job, how I fed my family.
History lesson over.  :o
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Alan Klein

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #111 on: January 31, 2019, 11:57:32 am »

Aram and Andrew: I bow to your experience. But I'm wondering if all that was mainly for studio control? How did you handle landscape photography with constantly changing lighting conditions?  That's when I was referring to shooting with caution when you were using the 35mm camera's meter to set exposure.  You were using center weighted or overall metering depending on the camera and era.  Spots weren't available.  And shooting a little faster not to blow the highlights.

digitaldog

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #112 on: January 31, 2019, 12:10:16 pm »

Aram and Andrew: I bow to your experience. But I'm wondering if all that was mainly for studio control? How did you handle landscape photography with constantly changing lighting conditions?  That's when I was referring to shooting with caution when you were using the 35mm camera's meter to set exposure.  You were using center weighted or overall metering depending on the camera and era.  Spots weren't available.  And shooting a little faster not to blow the highlights.
IF you can bracket (based on sound and fundamental understanding of exposure as a basis) DO SO.
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smthopr

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #113 on: January 31, 2019, 12:36:34 pm »

The first is 'pushed' as it isn't an ideal exposure for raw as 'recommended' by the meter. The 2nd appears far too bright until (using Michaels term from the original ETTR article) normalized. Had the first been optimally exposed, it too would need to be normalized and wouldn't be as noisy. But the main take away is the incorrect concept that higher ISO always produces more noise as the OP implied.

Maybe. But, since the exposures here are the same, the difference must be in the gain applied to the Sensor capture, before the recording of the data, plus any image processing also applied by the camera software.  And so this is the result.

I work mostly with professional motion picture digital cameras.  Many of these do not process the image before the RAW capture and simply record an image exposed at higher ISO settings/exposure as "darker" or images with less amplitude.  It's only in post processing that the exposure is normalized.  So, in my case of movie work, the higher ISO image always has more noise. (The gain is applied in post processing).  I do wish that my Canon 5Ds would work the same way sometimes :), but it doesn't.

With the movie camera I always know that using a higher ISO will protect more highlights, at the expense of shadows.  And vice versa.

And as for exposure strategy, I aim for consistency, and not for "lowest noise".  So, generally, I know that if I'm working at ISO 800 (depending on the camera, this is the ISO that provides near equal dynamic range above and below the middle value), I have plenty of data to work with without clipping any wanted highlights.  And so, there is little reason for ETTR.  Once in a while, on a very high contrast image (typically a day exterior) I'll set the camera to show me the entire range of tones, as opposed to a "preview" that is like a jpg on a still camera.  And adjust the exposure accordingly.  Or, I'll just use my spot meter.  And sometimes, when shooting a very dark scene, I'll shoot at a lower ISO, so that the on set preview is good and dark, but I'lll know that my exposure now will allow me to lighten it a little in post production, without excessive noise, when necessary.

When shooting stills, because my Canon 5Ds adds gain before the RAW recording, when using higher ISO settings, I need to adjust the "exposure compensation" instead of the ISO setting to get the same results or protect the highlights.  It would be nice, therefore, if the 5D had a jpg setting for LOG gamma, or maybe "full dynamic range" in order to preview the clipping points.  And then, the histograms would be accurate for adjusting exposure in extreme conditions.  I think there might be some Sony cameras that allow this in still photography mode, but I'm not sure.  These images wouldn't be so good for color correction as the compressed jpgs would fall apart when adding in the missing contrast.  This is certainly the case when shooting movies on a Sony A7RII camera in LOG mode and recording the movie in the camera.  But if one records to an outboard recorder, this situation improves quite a bit, but is still limited to 8 bits which can cause some banding.  But for a purely "exposure preview" plus a RAW capture, for still photography,  I'd like to see this feature!
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bjanes

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #114 on: January 31, 2019, 06:47:45 pm »

No, we pros didn't because clipping highlights we didn't want to clip is over exposing!

Of course you want to get exposure exactly right.  But metering is not always an exact science.  If the photographer is concerned that he might blow the highlights and ruin the shot, he'd play it cautious and shoot 1/3 or 1/2 of a stop slower.  There were no histograms back then.  Certainly nothing where you could ETTR which has no point with film in any case.

Andrew,

Out of the many thousands of exposures of E6 film in your professional career, did you ever have a less than optimally exposed image? I would think that the answer would be yes, since metering is not an exact science as Alan points out in his post. In these cases, it is helpful to have tools to improve a less than optimally exposed image. Like Jim Kasson, I still use the term ETTR for shots at base ISO and use the histogram and blinkies in evaluating exposure and think the term ETTR is appropriate, since it denotes that the histogram was used in the evaluation. Proper exposure is a less than helpful term IMO.

Even when shooting with ISOs above base, the histogram is helpful in that a shot with a histogram to the left is leaving image quality on the table when one is shooting in raw. Raising ISO to move the histogram to the right will not improve the situation if one uses the same exposure (f/stop and shutter speed), but will only decrease highlight headroom.

As I recall from film days, many photographers would underexpose (if you forgive the term) by 1/3 EV with reversal film mainly to improve color and saturation more than to protect the highlights. One third EV under will provide minimal highlight protection.

Regards,

Bill
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digitaldog

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #115 on: January 31, 2019, 06:55:24 pm »

Andrew,
Out of the many thousands of exposures of E6 film in your professional career, did you ever have a less than optimally exposed image?
I'm sure I did. When I shot the 1984 Olympic games, about 100 rolls a day, in so many different venues, pretty sure I didn't nail them all. But those brain cells are long gone.
Metering isn't an exact science but I know how my tools behave and when they are dead wrong; examples provided.

Quote
As I recall from film days, many photographers would underexpose (if you forgive the term) by 1/3 EV with reversal film mainly to improve color and saturation more than to protect the highlights. One third EV under will provide minimal highlight protection.
I can only speak for the professionals I've shot with and myself. We might COMPENSATE 1/3 over or under what a dumb meter suggested because we understood how our tools worked. What Alan stated was simply wrong: we didn't UNDER EXPOSE to avoid clipping highlights. We exposed FOR the highlights. We understood based on our tools when and how to do so. That's absolutely NOT under exposing. That's simply a misstatement based on misunderstanding. If you or anyone else here thinks the meter knows what we want and should blindly follow it, otherwise an adjustment based on a through understanding of the tools is over or under exposing, doesn't understand what exposure is. I can assure you, it's not what the meter demands. It is what the knowledgeable photographer sets.
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Alan Klein

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Re: Optimize In Camera Jpeg White Balance RGB Histogram For Better ETTR.
« Reply #116 on: January 31, 2019, 10:28:51 pm »

Andrew, We actually agree.  It's just that we're using different words to say the same thing. 
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