Because I don’t want my camera making any decisions for me, I’ve always metered in manual mode. For most of my photography life, my manual metering approach was to start with the best f-stop for my composition, spot-meter on the brightest part of the scene, and dial my shutter speed until the meter indicated the proper tone. In my film days I sometimes hedged my bets by bracketing high dynamic range scenes; with a digital camera, rather than bracket, I check my histogram and re-shoot only if I missed the exposure on the first try. While this approach has served me well, my metering life became much easier with the advent of live-view (pre-capture) histograms, and easier still since my switch to mirrorless.
Trust your histogram
The histogram is a graph of the tones in an image (you can read more about it here). Instead of clicking and hoping as we did in the film days, the addition of a histogram on virtually every digital camera gave photographers instant feedback on the exposure of every image. Better still, live-view histograms give us that exposure feedback before clicking the shutter.
Each camera manufacturer uses its own metering mode terminology. Whatever your camera, instead of spot metering, choose a metering mode that uses the entire frame. With my Sony mirrorless bodies, I set my metering mode to Entire Screen Average.
Using the pre-capture histogram, I start the metering process as I always have, using my camera’s best ISO (1oo for the Sony a7RIII), and the best f-stop for my composition (unless motion, such as wind or star motion, forces me to compromise my ISO and/or f-stop). With ISO and f-stop set, I slowly adjust my shutter speed with my eye on the histogram in my viewfinder* (or LCD) until I’m satisfied with the histogram. Ideally I’ll have a little room on both sides of the histogram, but in a high dynamic range scene my histogram might not fit the boundaries, and I’ll add exposure until the histogram bumps against the right side.
Most mirrorless bodies offer highlight warnings in their pre-capture view (called “zebras” on my Sonys). While these alerts aren’t nearly as reliable as the histogram and should never be relied on for exposure decisions, I use them as a signal to check my histogram. The first time I meter a scene, my current exposure settings can be far off from where I’ll end up—in this case, I push my shutter speed fast until the zebras appear, then refine the exposure using the histogram.
Because I trust the post-capture histogram a little more than the pre-capture histogram, when there’s little margin for error in my exposure, I verify it by checking the review (post-capture) histogram. While the luminosity (white) histogram gives you the detail you captured, it doesn’t tell you if you lost color. Washed out color is always a risk when you push the histogram all the way to the right, so it’s best to check the RGB (red, green, blue) histogram to ensure that none of the image’s color channels are clipped.
An often overlooked aspect of mastering in-camera metering is learning your camera. Not only does every camera interpret and report its exposure information a little differently, the histogram returns is a jpeg histogram—raw shooters almost always have more information than their camera reports and it’s important to know how much more. For example, with my Sony a7R bodies, I know I’m usually safe pushing my histogram’s exposure graph a full stop beyond the boundary, and I have no problem using every available photon.
A few years ago I was photographing a sunrise at Trillium Lake just south of the Columbia River Gorge. Finding the open sky on Mt. Hood’s east side much brighter than the lake and (especially) trees, after composing and focusing, I cranked my shutter speed until the zebras appeared (they usually show up before the histogram reaches the right side), then clicked more deliberately until the histogram hit the right side.
At that point the left side of the histogram was still clipped slightly, but because I knew I still had one more stop to play with on the highlights side, I clicked one more time with my eye on the left (shadows) side of the histogram and saw that the shadows were still slightly clipped. Since each click adds (or subtracts) 1/3 stop, I had two more clicks before I reached my 1-stop-over highlight threshold. The second shutter speed click moved the left side of the histogram just enough to eliminate the shadows clipping, and I was ready to shoot (with 1/3 stop to spare!).
After capture, I checked my review RGB histogram to ensure that I’d captured all the scene’s detail and color. In Lightroom I was able to easily recover the highlights that my camera told me were clipped, and pull all the detail I needed from the shadows.