Shooting to the histogram

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andyturk

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After a recent workshop I've been trying to get away from relying on the meter and instead use the in-camera histogram to determine the best exposure. I spent two days out shooting with the technique.

I'd take a shot and then bring up the histogram. I tuned the exposure until the curve barely kissed the right edge. All my shots were in RAW format, so I'd bring them home and use ACR in Photoshop to process the images. Imagine my surprise when shots that looked perfectly exposed with the in-camera histogram came out about 1.5 stops under according to Photoshop.

After much gnashing of teeth I did figure out what the problem was. The Epson, like most digital cameras, calculates a histogram based on the image that's displayed on the LCD. Raw data is processed using whatever film settings were chosen and then a histogram is derived from the resulting image. The point is that the histogram doesn't necessarily represent the raw image data.

In my case, I was using the Epson's B&W mode with a yellow filter applied. I also had the contrast and saturation punched up in the film setting. Big mistake. The contrast and saturation enhancements brightened the in-camera .jpgs significantly.

Now I use a film setting that minimizes all the parameters except for tint. Shots look very washed out an uninteresting on the LCD screen, but the histograms match what ACR sees in the raw image, which to me is most important.

82846120-M.jpg
 
I've observed the same thing using the histogram to fine tune exposure. However, I have noticed that ACR rarely shows correct exposure of the file. I think this is due to the settings it uses to balance exposure and brightness. I don't believe this is an issue related to the R-D1.

My Canon DSLR used to show perfect exposure settings (compared to in-camera exposure settings) with older versions of ACR. Now, I find with no setting changes related to the camer, I get funky exposure readouts with ACR in CS. Just my observation.
 
Dale Cook said:
I've observed the same thing using the histogram to fine tune exposure. However, I have noticed that ACR rarely shows correct exposure of the file. I think this is due to the settings it uses to balance exposure and brightness.
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Does ACR show incorrect histograms when you turn off all the Auto adjustments?
 
When I turn the default off, the values/sliders remain in the same position. Generally, I find the defualt values to illustrate a good exposure / brightness mix. However, I don't judge my shooting exposure as having been off by what I see for values in ACR.
 
In other words, I trust using the histogram to shoot correct exposure and worry less about what the "value" shows for exposure in ACR. When you turn on "blown highlights and lost shadow detail", I find my in-camera tuned exposure to be correct desipite what the ACR exposure reading is.
 
Dale Cook said:
Generally, I find the defualt values to illustrate a good exposure / brightness mix. However, I don't judge my shooting exposure as having been off by what I see for values in ACR.
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ACR does a nice job at auto adjustment, but I've set up mine to show exactly what came out of the camera. If I used exposure bracketing, for instance, I *want* to see three different exposures.

Looking back at some of my older images I realized that the camera was underexposing but ACR hid the mistake. The images were usable, but essentially had more noise than necessary. I'm hoping that taking complete control over exposure will (eventually) yield higher quality images. With lots of practice, of course.
 
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