Friday, October 1, 2010

Photo of the Day: "Highway in the Sky"

Nikon D90, Nikkor 18-135, 18mm, f14, 1/200 sec., ISO 100 (Lo1). Matrix meter, -2/3EV exposure compensation, landscape scene mode, raw (.NEF). Manual flash at full power, Kelvin white balance (5,200K with 4-green tune).

Frequent readers will recall how I've often complained about the 18-135mm Nikkor, and here is an illustration of one of the reasons why. With some heavy work in post processing I'm able to save an image, but it isn't the one I wanted. I've had to crop in too close on the left, when I wanted to leave some breathing room. (See the original below.) Unfortunately, because of the complex and severe distortion of the 18-135, such a crop doesn't work. The vertical lines on the mile marker aren't even close to parallel — and this is after significant tweaking with Photoshop's lens correction module. Perhaps if I had DxO...

I took several versions of this shot, trying to bring a number of different things together. First off, there is the need for depth of field, which forced me to get close and shoot at 18mm. (The wider your shot, the greater the depth of field.) I tried shooting without flash, and the mile marker was flat. This was returning from vacation, so I didn't have my external flash, limiting me to 1/200 sec. sync speed, which forced me to drop to ISO-e 100, or "Lo1." f14 is one stop beyond max sharpness with the D90/18-135 combination, but I thought it was a fair compromise, and I needed the depth of field, anyway.

Post processing is pretty significant. I tweaked the white balance a hair, increased saturation and did some serious color correction. The green channel is hue-shifted from blue toward yellow (look at the sign in the original below), while I've shifted yellow toward orange. I've increased the yellow, orange, blue, green and cyan saturation levels, and played with the luminescence values on the yellow and orange channels to get the ground color right. (Lumi values are how bright a color is, saturation is how much color there is. I have increased the saturation and decreased the lumi of the blue sky from before to after.) I also cropped, rotated a hair and used some advanced sharpening, along with the crazy lens distortion correction attempt. (Note how the vertical line on the inside of the mile marker remains convex even after correction.)

Whining aside, this is one of my favorite photographs. I would like very much to return to this place with a wide lens possessive of more correctable distortion.

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