Posted on May 10, 2015
In my previous blog I wrote about the flexibility of carrying three mirrorless (compact) bodies, each with its own strengths: the Sony a7R, a7S, and a6000. The a7S is my low-light body; it enables me to freeze motion and extract detail in conditions the were previously impossible. But more than that, I’ve discovered the a7S also makes photography that I’ve been doing for years, noticeably better.
Once upon a time
I got the a7S largely for its ability to pull light out of moonless night scenes, but the more I use it, the more I appreciate the way my a7S eliminates shortcomings I’ve wrestled with in my ten years of moonlight photography. As bright as a full moon is, the sun is nearly 500,000 times brighter (look it up), so achieving adequate moonlight exposure has always required pushing my camera’s light gathering settings to their quality threatening extremes, combining my lens’s widest, poorest quality aperture with star streaking 30-second exposures.
Mitigating these shortcomings meant increasing ISO, but with more sensitivity comes more noise. As high ISO and noise reduction software capabilities improve, so does the quality of my moonlight images, but the improvement has been slow and steady, only marginally perceptible. And it’s not been enough to push me out of the compromised exposure settings zone.
A new paradigm
Enter the a7S. With its spacious sensor and large photosites, the a7S offers ridiculous low light capabilities and I no longer think twice about shooting at 3200, 6400, or 12,800 ISO. And if I need to go higher than that, I know I have at least two more stops of ISO that usually cleans up quite nicely. Suddenly, I’m free to select an aperture I know will ensure the best quality, and a shutter speed that will freeze the stars, then just crank my ISO to a value that delivers the amount of light I want.
But wait, there’s more
Since I’m always on a tripod, most of my lenses are f4—I just can’t justify the bulk and expense of faster glass. But one downside of f4 glass is a less bright viewfinder, making composition and focus difficult in low light. Composition is often by trial and error, but it’s not too bad (and certainly easier than moonless scenes). My moonlight focus solution has always been to compose my shot on the tripod, detach the camera, turn and autofocus on the moon, then return my camera to the tripod—adequate, but a pain.
My a7S sucks so much light into my electronic viewfinder that composition and manual focus in moonlight are a fast, single-step process (I’m guessing moonlight autofocus works too, but I haven’t tried it). Whether I want to focus on the stars, or a particular foreground subject, I simply compose and dial in the sharpness.
I’ve learned that teaching people moonlight photography in the moonbow chaos on the bridge beneath Lower Yosemite Fall is a recipe for disaster, so I usually take my groups out to El Capitan Meadow the night before our moonbow shoot. This spot is easy to get to, it has lots of room, an iconic Yosemite subject, and not too much light pollution (we can just shoot over the headlights). But I go here so much with my groups, I rarely get my camera out anymore.
This month’s group seemed to be doing fine, and I couldn’t resist the sight of the Big Dipper hanging above El Capitan, so I set up my camera and tried a couple of frames with the a7S. Rather than using my standard moonlight recipe (that I’ve been teaching for years)—ISO 800, f4, 20 seconds—I went to a fast shutter speed and mid-range aperture I’ve always longed for (8 seconds, f8) , and compensated with ISO 6400. In my viewfinder El Capitan throbbed with moonlight, and the stars of the Big Dipper stood out like a glow-in-the-dark star chart, making composition and focus effortless.
On my computer back in the hotel I magnified the image to 100 percent in steps, scrutinizing each magnification for noise. I saw none until I got to 100 percent, when I could detect a fine texture in the void between the stars. This cleaned up easily with very low-level noise reduction (Topaz). Examining the image for sharpness and star motion was pure joy as I realized I’d just captured my sharpest, cleanest moonlight image ever.
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