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--- playground:exposure_to_the_right_ettr [2014/01/25 10:10] – created mgrant
+++ playground:exposure_to_the_right_ettr [2014/01/25 12:20] – mgrant
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-====== Exposure to the right (ETTR) ======
+====== Auto Exposure to the right (ETTR) ======
-Exposure to the right (ETTR) is a technique of setting the exposure of a scene such that few or no pixels are are over exposed (blown out) thus maximizing the information captured without loosing information to over-exposure.  This may produce a darker image but this can be corrected later in post processing.  The exposure curve is thus as far to the right as possible without it being clipped.
+Automatic Exposure to the Right (ETTR or AETTR) is a technique of setting the exposure of a scene such that few or no pixels are are over exposed (blown out) thus maximizing the information captured without loosing information to over-exposure.  This may produce a darker image but this can be corrected later in post processing.  The exposure curve is thus as far to the right as possible without it being clipped.
 For more information on ETTR, see these articles on Luminous Landscape:
@@ Line 11: / Line 11: @@
 The first method involves taking 2 images.  A photo is taken then ETTR looks at it and it modifies the exposure for the next photo.  There are two ways to use this method: **Always on** and **Auto snap**.  The Always on setting sets the ETTR for the next photo on //every photo// you take for the next photo.  The Auto snap setting takes a photo, calculates the ETTR, and then if necessary takes the second photo immediately.
-The second method uses the live view momentarily to run through a series of exposures until the exposure is correct without taking a photo.  You then take the photo.
+The second method uses the live view momentarily without taking a photo.  You then take the photo.
 ETTR sets the shutter speed and ISO.  It does not change the aperture setting thus not altering the depth of field of the scene.
+====== The Settings ======
 In the Expo Tab (Exposure Menu of ML) you will find Auto ETTR:
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 Pressing the **Q** button brings you to the settings menu of the ETTR function
-==== The Settings ====
 {{:playground:aettr3.jpg|ETTR Info Screen}}
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 **Shadow SNR limit**: 2  Is defined in EV levels of noise form 1 to 4 EV.  The higher the SNR the less noise.  Typical settings from 2 to 4 EV.  For a Timelapse we recommend 2 or 3.
-==== The Advanced settings ====
+====== The Advanced settings ======
 {{:playground:aettr0.jpg|}}
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 **Show debug info**: ON OFF.  Will show some of the important calculation results of this module.
-==== Visual Feedback ====
+====== Visual Feedback ======
 If you want more visual feedback to see how the image is (and you will need it for **Always on** and **Auto snap**), enable histograms and raw zebras:
@@ Line 73: / Line 73: @@
 Also in the **Overlay Tab** you can scroll to **Zebras**, press **Q**, and make sure that **RAW zebras** are ON.   The **RAW zebras** will show on the image itself to mark the areas where a color channel may be overblown.
+{{:playground:aettr4.jpg|}}
+====== Step by step intructions ======
-===== Setting it up =====
 ETTR in RAW images  - HOW TO USE IT (step-by-step):
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 . Press trash button to exit ML menu.
-===== Usage =====
+====== Usage ======
 You are highly recommended to use a tri-pod or other support.  Multiple images or measurments of the scene will be taken and you do not want to change the scene much between measurements.  Also the shutter speed chosen may be quite low.
-==== Always On mode ====
+===== Always On mode =====
 . Frame you subject and set the aperture (for the DOF) and shoot a test photo.
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 . Shoot another a photo and repeat to step 2 until your photo is not over exposed (few or no zebra lines, and the exposure curve up to the right side of the graph).
-==== Auto snap mode ====
+===== Auto snap mode =====
 . Frame you subject and set the aperture (for the DOF).
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 . Now look at the display and you should see the second image with the histogram and the zebras in the over exposed areas (if you enabled them).  If your photo is over exposed, press the shutter again.  The camera will take at least one (and maybe a second photo) again.  Repeat until there are few or no zebra lines and the exposure curve is up to the right of the graph.
-==== Press Set and HalfS DblClick modes ====
+===== Press Set and HalfS DblClick modes =====
 . Frame you subject and set the aperture (for the DOF).
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 . Do not recompose your shot.  Shoot the scene.
-==== Using the histogram ====
+===== Using the histogram =====
 Inside this histogram you may see near the top-left of the graph, in white lettering, the letter E followed by a number which represents how far you can go, in EV numbers, to reach ETTR, i.e E1.2
@@ Line 150: / Line 150: @@
 If the camera beeps it means that the photo is out of specs and you should shoot again.  In the tests I ran I found that in extreme situations the adjustment was completed in three photos.  For most situations the adjustment is done in one shot.
-===== Convergence to results =====
+====== Convergence to results ======
 With the **Always on** and **Auto snap** setting which takes images, it may require at least two images (sometimes three or four) to come up with the proper exposure.  Alternatively you can set the Trigger mode to **Press Set** or **HalfS DblClick** in which case the camera will go to live view, analyze the scene, and return to photo mode with the correct settings.