ETTR — the return of the spotmeter?

From the mailbag:

With a hint and some assistance from George Jardine, I finally figured out how to optimize exposure (ETTR).

The key was George’s statement that he spot metered for the highest significant tone, and placed it just under clipping.

As you have found, the histogram lies and matrix, evaluative, center weighted metering is not reliable to meter and add an offset…even with white balance manipulations.

You are correct….LR 4 automatically applies recovery.  If you test against RawDigger, you will find that any LR highlight above 95-96 is clipped in at least one channel, usually the green.

With testing, I have found that adding +3 EC to the spot metered highlight will create an LR image with the highest (significant) highlight at the 95-96 point.

Try it, I think you will agree.  The beauty is it is absolutely consistent.

Metering his way also is a good way to do HDR bracketing.  ETTR, this way, will maximize dynamic range capture.  If the entire low end of the range is not included in the histogram, bracket steps of higher EC until the low end has a significant gap away from the left edge.

Hope this helps….and that I am not preaching to the choir…..

Shades of the old days!  I see no reason why this won’t work, but there are some caveats.

• You need to be able to make sure you can find the key highlight.
• The key highlight needs to subtend a visual angle greater than or equal to one degree.
• Your spotmeter and the sensor need to be calibrated to each other, and that calibration needs to track over temperature.
• The highlight can’t have high chromaticity, since the spotmeter at best responds to luminance, and, at worst responds to some spectral curve peculiar to its photon detector.

I will dust off my Minolta Spotmeter F and give it a try.