Reviewed by Carl Weese
For the pictures I make with digital capture, my concerns about sensor performance, on a scale of 1–10, have put exposure range at 9 or 10 and high ISO performance down about 5. Give me a choice of an extra 1.0 EV of exposure range or an extra 1.0 EV of acceptable high ISO, and I’ll take the exposure range without hesitation. This is mainly because exposure range still lags behind negative film, while high speed results surpassed film ages ago ("ages" digitally speaking). But I didn't know how much farther they had come recently.
When I'd caught up with comments on the first GX7 post after a weekend away in NYC with dicey Internet service, I found that commenter Steve Goldenberg had asked, "Have you tried a 6400 print from this yet? They're simply astoundingly good." I had not. So I made a series of snaps in the kitchen at night, 800, 1600, 3200, 6400. Of course they're noisy at 100% view, but the increase is quite moderate as the speed goes up, and even at 6400 the noise remains random, without the repeating patterns that scream "digital noise!" After adjusting the 6400 file in ACR and reducing it for letter-size paper in Photoshop CC, I applied a modest amount of Smart Sharpen and sent it to my Epson 3880. The print is surprising. There's noise, but you really have to look for it in the highlights and mid-tones, and even in smooth darker areas it doesn't hit you over the head. If you look close enough, there is some chroma noise in shadow areas that would detract from some pictures.
Rather than comparing the GX7 to other current cameras (to which I have no access anyway) what I can compare to is B&W film used at high speed (I never used color film faster than Kodachrome 200). I went back to the RAW file, converted it to monochrome in ACR, tweaked some of the adjustments, then prepared it for letter-size printing. The noise in that print is even less noticeable.
Here's an example of what I think of as "good grain." This is Tri-X from long ago, push-developed in Acufine for exposure at E.I. 1200 (to be fair, more recent Tri-X and other films would be less grainy even when pushed to this speed, and of course you can't evaluate anything based on the web JPEG—these illustrations are just to let you get an idea of the pictures/prints I'll describe).
The grain is obvious in a print, but, typical of Tri-X, it's really beautiful and I think makes a positive contribution to the moody, gritty sense of the picture.
Would real world pictures made at very high ISO with the GX7 do something similar? What I found was a complete surprise. Wednesday was a dark, stormy day. I decided to go out and look for subjects that would give me an excuse to use ISO 6400.
This is a really, really, dark passageway, through an old industrial complex, in a light rain under a heavy sky. I wanted a crisp picture of all this detail and texture, with lots of depth of field. Getting 200th @ ƒ/8 justified high ISO. I intended it for monochrome conversion.
This is in an even darker area beneath the elevated walkway near the stairs you see in the first shot. I thought this would make a good color test, and the 6400 exposure has fallen to 100th @ ƒ/5. At this fairly close distance, keeping the railing and the bricks in focus wouldn't happen at a wide aperture like ƒ/2.
After working up the two files in ACR, then slightly downsizing to about 11x14 and applying a fairly small amount of Smart Sharpen in Photoshop CC, I printed the pair with my HP Z3200. The prints are, to quote Steve, "astounding." The noise in the mono print seems to me only the slightest bit more noticeable than the grain in a print this size from normally exposed and developed 35mm Tri-X. The color print doesn't show obvious noise unless I bury my nose in the smooth-toned bricks on the left. It's much less obvious than the grain in a Kodachrome 200 35mm transparency printed or reproduced at this size. While typing up these notes on my MacBook at the kitchen table, I've gotten up half a dozen times to walk back to the printer room and look at the pair of test prints again, to make sure I'm not imagining things. I've been aware of people's rave reviews of high ISO performance on "full frame" sensors but I had no idea things were moving to this level with smaller sensor cameras. I'm suddenly much more interested in high ISO capture than I was last week.
Now, there's a bit of a cheat going on here because these pictures have tight texture and detail everywhere, which does a good job of hiding grain or noise. Pictures with lots of smooth non-detailed areas of tone wouldn't fare so well. But I'm going to raise the upper limit on the camera's auto-ISO control.
Next time, we will get to features and camera-handling.
©2013 by Carl Weese, all rights reserved
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