On any photographic forum, it doesn’t take much effort to find old or new discussions on how to set the “proper” exposure while shooting, and even what exactly “proper exposure” is. The question of setting exposure was and is one of the most commonly-discussed topics on forums and blogs. Newbies (and not) bring it up again and again and receive all sorts of explanations – long and short, deeply “scientific” and completely “practical”, starting with advice to use the in-camera histogram, “zebras”, manual exposure mode, corrections and compensation, special camera modes to increase the dynamic range and increase the reliability of the histogram and other overexposure indicators, a separate exposure meter, Adams’s exposure formula, metering the incident light, spot measurement, a grey card, the back of one’s hand, green grass, an ExpoDisk, the sunny 16 rule, Magic Cube, etc., etc.
DIY projects are always popular, so we’ve decided to throw another one into the mix. This particular little idea comes from a problem that many photographers have – where do you get a good, small, white/gray surface to use for white balancing your RAW shots in conversion?
Suppose you have read somewhere that the dynamic range of your camera at a certain ISO setting is 11 stops. And here comes the immediate question – how can one use such a treasure to its full potential? Optimal exposure for RAW is the answer. But now we need to explain what we mean when we say, “optimal exposure for RAW”. Let’s start with one of the problems, which arises as a result of non-optimal exposure for RAW. Here is a typical wide dynamic range low-light scene. According to Sekonic spot-meter, it is wider than 11 stops:
As we already mentioned in the previous article “Where are my Mid-tones?“, most raw converters apply some hidden adjustments to a raw shot, often resulting in a bumped mid-tone, clipped highlights, and compressed shadows. This is done to make the shot look good, but can also lead to all sorts of confusion. If you are using or planning to use some raw converter, you may want to know what “beautifiers” it applies, and their price.
We’ve gotten several emails, the most recent and the best phrased one from a reader of Photography Life, with questions along the following lines:
What happened to my mid-tones? I set the exposure using exposure meter, opened the shot in Adobe Lr (or Adobe Camera Raw, or some other converter) … and the shot looks overexposed and everything from mid-tone and up looks very flat. If I shoot in RAW+JPEG, the JPEG looks OK, while the RAW is not. Should I expose lower?
We’ve decided that the reply to this question belongs here.
You may find this article to be useful in a practical way, not just as an isolated case of RAW data damage. Often, just a casual look into raw data provides arguments allowing one to persuade technical support that there is a problem with your camera body that needs to be addressed. The case started with this post at DPReview:
What do you think is the possibility, when you are choosing and sorting images based on the JPEG previews, that you are going to discard the better-quality image, and keep the lesser-quality one? Let’s take a look at a typical “training” shot for a holiday – noon of a sunny day, blue Ionian sea, bright white limestone pebbles, bushes with dark-green, high-detail leaves (which lose all detail if the shot is underexposed), deep shadows under the bushes. These types of scenes typically have a very wide dynamic range. We will see later, however, that the real range of the shot we are examining is pretty much only 8 EV, if the exposure is technically correct.
It reminds me of Goldoni’s “Servant of Two Masters“; only masters are now more than two and quite often they are not only capricious but they do not know what they want. First, any comparison is open to critics because even in a well-equipped lab it is impossible to repeat the shooting conditions from a year ago, or even from a day before while shooting to compare a newer model to an older one; the criteria for necessary accuracy is not set, or not made public, or not recognized by the community. Second, one single body in the testing opens the door for sample variation questions; and once again tolerances are not brought to the light. Third, using different lenses for different mounts does not help leveling the field. Using lens adapters to shoot with the same lens is often suggested, but it opens another can of worms: adapter alignment problems and different amounts of internal flare added by different adapters skew the results.
When using Lightroom, you might be wondering why the highlight recovery between different camera models allows for different room. Given the “color of light” (light source color temperature and tint) is the same, the highlight recovery difference depends primarily on baseline exposure compensation applied to a raw file when it is opened in Adobe raw converters (Adobe Camera Raw, ACR; or Lightroom, LR). This baseline exposure compensation is applied behind the scenes, the exposure compensation slider after the file is opened stays at zero. This is Adobe’s way to equalize cameras.
I guess today is a “blow your mind” Friday, because we have a guest post here by Iliah Borg, the person behind the RawDigger software that is used to analyze RAW images. I had a chance to engage in a conversation with Iliah when discussing the noise performance of the Nikon Df, where he not only proved me wrong on my assumption that the Df had exactly the same sensor as the D4 (turns out that they are similar, but not exactly the same), but also shared some incredible information about testing procedures, data analysis and other crazy, mind-boggling stuff! The learning curve with photography never ends, especially when you get into the whole sensor and image processing pipeline side of it. I must warn our readers though – the below article is very technical and is not intended for beginners! Hope you enjoy it! Nasim.