allyn_saroyan

<p>Andrew,</p> <p> I do not use JPEG. Everything I reported is from RAW data. The light meter exposure puts the highlight on the high end of the raw data. JPEGs play no part in my work.</p> <p>ETTR is in general not using the entire range of the camera because the JPEG histogram is not indicating how much more room is available in the raw data, it only indicates how much room you have in a JPEG image processed the way the camera did. </p> <p>I am not sure why you think the external meter is underexposing. It does what all meters do, it gives the exposure for middle gray, the standard scene. When you measure with a spot meter the indicated value will always give you the exposure to render what you metered as middle grey. The camera's meter system is the same (see the CIPA specification for calibrating them). What camera manufacturers do is add intelligence to the meter reading by guessing what you are photographing and biasing the exposure accordingly. In the Zone System, the photographer supplies the intelligence.</p> <p>ETTR is not bad, it is just not optimal. Most folks simply do not want to use a hand held meter and have no problem taking multiple exposures to get what they need. I am not advocating the use of the Zone System, only trying to reply to the original poster who appears to want to use it.</p> <p> I suspect that the original poster's low values were created by his camera exposure system and if he had an independent light meter, he would get the expected values of 118 or 98, depending upon the ACR color space setting.</p> <p>To repeat, the external meter is not under exposing. It is giving the exposure for the standard scene. All light meters do this including the ones in digital cameras. A Zone System Photographer adjusts a handheld meter to the desired zone. Doing so moves the exposure so that the raw file contains all the data it can. It is automatic expose to the right, far right, just as John Shaw says you should.</p> <p>Allyn</p>

<p>Andrew,<br> The point I was trying to get across with the experiment was that camera manufactures have built in biases on how the standard scene is rendered. Some decrease exposure (Sony) and some increase it (Nikon). The hand held meter removes this bias and produces the expected result for the gray card and the Zone System.</p> <p>Expose to the right was created to make sure that the shadows have minimum noise and that you are getting the full benefit of the sensor. This works only in the case where the highlights are not already at the top of the camera's recording ability. Since in the example I gave I am already placing the scene highlight on the highest zone my camera can record, in post processing I will not change the exposure to drop the highlights. And I will have already gotten as much noise free shadow detail as the camera can provide. I might still adjust the exposure since it is a mid tone adjustment but I will constrain the highlights. </p> <p>I am not quite sure if I have answered your question. ETTR practitioners do what you described. In general they are not getting the full benefit of the sensor. John Shaw wrote an article for Visionary Wild in which he discusses the pitfalls of using the histogram for ETTR. https://visionarywild.com/2012/12/24/exposing-to-the-right-the-far-right/</p> <p>A Zone System exposure as I described may appear blown out in the camera but Lightroom automatically brings the exposure down as described in the Jardine video. I definitely post process, dropping highlights to taste, raising shadows, adding contrast, etc.</p> <p>The fundamental value of the Zone system for me is that I can make a single exposure to get the data I want. With modern cameras, it is rare that I need HDR or worry about noise.</p> <p>Allyn</p>

<p>I found George Jardine's video to be very well done. He made one point I would like to make in a slightly different manner. There are three Zone Spaces of interest to the Zone System Photographer: The Scene Zones (unlimited), the Camera Texture Zones (found by testing), and the Print Zones (Ansel Adams 10 zones which have so far not changed in the digital world). A digital photographer is either mapping the Scene Zones to a screen image (for the Web) or to a print via Lightroom or its equivalent.</p> <p>With regard to the values obtained by photographing a gray card, I performed an experiment with two of my cameras (Nikon D800, Sony A7R). In both cases I photographed two ways: First I let the camera pick the exposure in Aperture Priority, ISO 100. Then I used a Sekonic L-758 meter to determine the exposure and photographed in manual mode. The target was a Sekonic 18% gray card produced by Musell Color. Adobe ACR was used to measure the 8-bit gray scale values in ProPhoto color space. The results were interesting: D800 autoexposure 163; Manual exposure 98. A7R autoexposure 67; manual exposure 109. The expected value is 98.</p> <p>This experiment confirms my belief that only a hand held light meter reading combined with manual exposure mode will yield predictable results when using the Zone System.</p> <p>With regard to using gray cards for exposure setting, the card is a reasonable substitute for an incident meter only if the card is in the same light as the subject. This is true in a studio but not in general for a landscape.</p> <p>For my photography, knowing the texture range of my cameras, I meter something whose zone I know or desire and adjust the exposure given by the meter to match that zone. For example, I might meter a highlight such as a cloud and increase the Zone V exposure indicated by the meter by an amount to reach the highest texture zone my camera can record. Thus if my camera's highest texture zone is 7, I would add two stops to the meter reading.</p> <p>At its most trivial level, the Zone System can be seen as the scientific way to expose to the right. Scientific because you are relying on the measured response of your camera rather than an 8-bit histogram produce by the camera from a JPEG image.</p> <p>In post processing, knowing that I have captured all the data my camera is capable of, I manipulate the image in Lightroom to obtain the print I desire. This is no different than the original Zone System in which film processing was altered in order to capture the scene range and dodging and burning was used during printing to reproduce the original scene or vision.</p> <p>I hope these notes help. Absolute numbers are not the goal. Producing a good image is.</p> <p>Allyn</p>

<p>The expected 8-bit value for a gray card is 118 for Adobe RGB 1998 or sRGB and 98 for ProPhoto color spaces. Digital cameras are calibrated to a specific 18% gray target and adjusted to obtain the 118 value in the sRGB color space. See the CIPA DC-004 Sensitivity PDF which can be found on the Web. <br> The reason that 128 is not the expected value is that all color spaces contain a gamma correction. That value is 2.2 for sRGB and Adobe RGB 1998 and 1.8 for ProPhoto.<br> The CIPA document shows the calculation used to get the desired 18% gray value. To get the ProPhoto value, you substitute 1.8 for the value of gamma. The standard uses a gamma of 2.2.<br> P.S. I am a digital camera Zone System practitioner.<br> Allyn</p>