OM-D LV blinkies fail with low DR scenes

Started Jun 24, 2012 | Discussions thread
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gollywop
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OM-D LV blinkies fail with low DR scenes
Jun 24, 2012

While participating in several recents mFT threads dealing with histograms and DR, I was led to delve more deeply into the behavior of the blinkies (and histograms) of the OM-D. And I discovered a rather unnerving fact: The Live View blinkies do not work properly (if at all) and the Live View histogram lies terribly when assessing a scene with very low dynamic range. [As a matter of interest, I should make clear that this issue has nothing to do with the histogram threshold or WB setting. Those issues are not of concern here.]

So take your OM-D and fill the FOV with a scene with very low DR: this can be a reasonably uniformly bright scene, or a reasonably uniformly dark scene, or a reasonably uniformly mid-range scene -- just be sure the tonal range is limited -- no areas that are way brighter than the rest of the scene. I did this, for example on a bunch of things on a bed in a darkish room, on a section of my deck that was in the shade, on a section of the deck that was in the sun, on a door in a lighted room, on some green ground cover that was all in the shade. All these were scenes with very little DR. They don't have to be tonally completely flat, just nothing relaltively strongly reflecting any nearby light.

Now, set the aperture in A mode and, using highlight preview, start bringing EC up. Keep going until you see the blinkies, although you may not (probably will not) see any at all even when you reach the limit of +3EV. Switch now and note the Live View histogram; it probably looks fine, showing no clipping, humped in the middle with gaps to either side. Take the shot. Now assess the shot with after-shot blinkies and with after-shot histograms. Depending on the nature of the shot, you may now see either no after-shot blinkies, or some after-shot blinkies, or a whole bunch of after-shot blinkies (this can happen with a darkish scene having some moderate DR with lighter and darker objects). But the after-shot histograms will almost certainly be pushed way to the right and showing substantial clipping.

You can do this using S mode, adjusting EC, or you can do it using M mode, adjusting S and A as you will to gain a +3EV reading. The same thing happens.

This appears to be an issue only with the Live View exposure aids: blinkies and histograms. The after-shot histograms appear to tell something close to the truth. The after-shot blinkies may or may not tell a proper story.

This is not an issue with the camera's metering system. Once you've set a proper exposure (albeit without the aid of the Live View blinkies or histograms), the camera has no trouble taking a correct shot, and it will be reasonably accurately reflected in the after-shot histograms.

How, then, do you set exposure in such low-DR situations? Maybe someone will come up with better methods, but the best I've found are the old dSLR techniques: take the shot with EC at 0 (let the camera's metering do its regular thing), examine the after-shot histograms, and adjust EC as needed. Or, spot meter the brightest part of the scene with +2.0EV EC, hit AEL, recompose, and shoot. This is actually very effective. Both of these are painful methods once one has gotten used to using Live View blinkies, but it's what we used to do before they were available.

The Live View blinkies seem to work just fine when there is fair DR to the scene and, indeed, under those circumstances they can often be more accurate indicators of clipping than the histograms. But, for low-DR scenes, it appears you've got to rely on the after-shot assessment.
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gollywop

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