Photo Tip on Exposures: Of Elephants and Hamsters (actually HAMSTTR)

September 11, 2009
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Photography on safari is very challenging.  Some animals are very white and one can easily blow the histogram to the right and lose information.  An example would be egrets and the yellow billed storks.  These are not the feature of this particular articles’ debate.

Other animals are quite dark, such as a hippo or an elephant.  Since the flats near the rivers are flat (duh), and the African sun is harsh, if you merely shoot scenes with no exposure compensation, you will often have two “humps”.  One way left with the dark animal, and one way right with the bright, dry grasses and sky.  Since I most value detail on the animal (this is why I brought my camera), I prefer to be able to recover good detail on the darker animal.  Due to this, I shoot in RAW mode and I often try to “expose right” to gather as much detail data is possible for later digital darkroom recovery.

This practice can create some debate, but my logic is supported by the following excellent review and references:

Traditional Histogram with lots of data left

Traditional Histogram with lots of data left

Exposure of same image shifted right to allow more data on right half of histogram

Exposure of same image shifted right to allow more data on right half of histogram

The following was posted by “CybeDyneSystems” on the Photography-on-the.net website at this link: http://photography-on-the.net/forum/showthread.php?t=744235

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What is “HAMSTTR”**© ?
“HAMSTTR”© ( Histogram And Meter Settings To The Right )

…Is a more accurate term to describe what we really mean when we say we “Expose To The Right” or ETTR. (from this point on I will use only the term HAMSTTR. Suffice it to say, that the term is new, and prior to August 2009 the universally used term to describe HAMSTTR was “ETTR” )

A brief History of “HAMSTTR”©.

  • In 2003 Michael Reichmann of Luminous Landscape fame, and early Digital Photography Pioneer, was conducting a workshop in Iceland attended by none other than Thomas Knoll ( Creator of Photoshop! )Thomas advised Michael to maximize the signal to noise ratio in Digital photography by adding what we call + EC (plus exposure compensation) while shooting RAW, and then if need be, using – EC during the RAW conversion to bring brightness levels back down to match the lighting at the time.
    Complete Article here;
    Expose to the Right – Maximizing S/N Ratio in Digital Photography
  • Others had been seeing similar results, and very quickly word spread around that this was in fact a very effective technique.
    Further Reading:
    Roger Cavanagh, and early POTN Contributor on Expose to the right

The advantages are several.

  • Total image information is increased as more of the histogram falls under that right most section.
    A 12 bit image is capable of recording 4,096 tonal values.
    The right most “stop” of the histogram (brightest) data contains 2048 of these steps — fully half of those available. Now we use 14 bit in modern DSLRs, but the effect of “HAMSTTR”© is the same.
  • Noise is reduced as more of the image falls to the right side of the histogram.
    HAMSTTR will minimize the noise that potentially occurs in the darker regions of the image.

So far so good, now fast forward to August 2009 and a simple question regarding ISO settings posted on POTN results in a 20 page long debate re: use of the word “exposure”

In nutshell, some old school purists would have it that we can not include the sensitivity of our cameras digital sensors in the “exposure” equation, because the current dictionary definition refers only to three components, ( luminance, Aperture, and shutter duration) …not four.
By this definition, even if your cameras meter and histogram say otherwise, a shot taken @
1/100, f/4, ISO 100 is in fact the exact same “exposure” as a shot taken
1/100, f/4, ISO 1600

By this definition the added sensitivity of the boosted ISO to 1600 does not alter the “exposure” but rather increases the brightness after the fact.

The trouble with this? Two fold:

1. It’s true!
2. We simply do not use the word “exposure” that way! Call it “incorrect” but the all the terms we use, EV, EC ETTR etc.. where E stands for Exposure, in our camera metering system, all of these are effected by ISO, when in fact, but this standard, ISO has no impact on the “true exposure” as defined by Luminance, Shutter duration and aperture.

In practice however, with digital (and even in film) we always include the sensitivity of the media or (ISO setting) in our calculations to make the image,. just as our equipment does this. In fact, the two tools we rely on most, absolutely include the ISO setting , in fact can not be asked to ignore it. The Histogram and Meter are effected by the ISO setting.

All of this may seem self evident however the use of the word “exposure” in these terms seems to create a semantic paradigm.

Use vs. Definition

It was then suggested that a new term need be applied for the “other half” of our ETTR adjustments, the ISO settings. This term proffered is ITTR for “Iso To The Right”

This is fine to a point, however it draws a line that in practice the vast majority of us do not differentiate, or even recognize when shooting. It forces the use of Two Terms to do the same action, as that one action uses both techniques together, the ETTR and ITTR to push the Histogram and Meter to the right.

“HAMSTTR”© is a solution to remedy this cumbersome dichotomy.

HAMSTTR refers directly to the real world tools and setting we use to push “ETTR” and “ITTR”
We use the Cameras built in Meter and Histogram Settings to give us the “To The Right” adjustments.

For the vast majority, of ETTR shooters, HAMSTTR is what we’ve been doing all along. Combining both ETTR and the ISO push seamlessly in one set of adjustments to achieve one goal. An image pushed + EC to give us the most from our digital cameras and RAW files.

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One Response to Photo Tip on Exposures: Of Elephants and Hamsters (actually HAMSTTR)

  1. [...] While I was forced to push the ISO, I tried to keep the histogram as far right as possible.  In the past, we’ve noted the importance of this in keeping noise under control.  Even when the ISO was shoved left, the images actually printed quite nicely.  That’s the [...]

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