How Was This Picture Made #10?

This is the tenth post in our “How Was This Picture Taken” series, and this one features a photograph I took at Great Sand Dunes National Park in Colorado. Since this is the tenth installment in our series, and because we have a number of exciting projects coming up, we’d like to do something a bit special this time:

The reader with the closest answer will receive a free copy of the eBook that Nasim and I are writing: “Creative Landscape Photography: Light, Vision, and Composition.” 

The answer has been posted here.

Before getting to the questions, here is a bit of background information:

I took this image at sunrise. Strong winds had erased every footprint from the dunes, which left a pristine canvas for landscape photography. There weren’t any clouds, so I focused on abstract images of shadows and lines in the sand. This image was taken with my Nikon D800e and 70-200mm lens. I needed a tripod because the sun was still low in the sky, so the dunes were not yet particularly bright. I took the photo at ISO 100.

Here are the questions:

1. This image is a blend of multiple photographs. Is it a focus stack, a luminosity/HDR blend, or a panorama?
2. What focal length did I use for this photograph? (If you believe that it is a panorama, use the focal length of the individual images within the blend.)
3. What were my shutter speed and aperture? (Name all exposures if you believe that it is an HDR/luminosity blend.)
4. Tiebreaker: Why did I convert this photograph to black and white?

The winning response will be judged as follows:

1. The questions are in order of importance — in other words, you must get the first question correct in order to win.
2. I used a focal length somewhere from 70mm to 200mm. To remain in the running, you simply need to guess within 30mm of the correct focal length, either above or below. Beyond that, it doesn’t matter how close you are (except for the tiebreaker); I will treat a perfect answer and an answer that is wrong by 30mm exactly the same.
3. For question three, you want to be as correct as possible on both the shutter speed and the aperture. If you are two stops over on the shutter speed and two stops under on aperture, they don’t cancel out!
4. In the event of a tie, the first tiebreaker is the millimeter value you guessed in question two. It doesn’t matter whether your answer is over or under — all that matters is the total number of millimeters between your guess and the correct answer. If that still results in a tie, the winner will be decided by question four: the reason I converted this image to black and white (an intentionally subjective question).
5. None of these are trick questions, but the nature of these questions means that the winner may be decided subjectively.
6. You must provide a response to all four questions in order to remain in the running, and you may only answer once. Feel free to ask questions to clarify any of the rules.

To have a shot at winning “Creative Landscape Photography,” or if you are simply interested in sharing your guess, leave an answer in the comments section below.