The dry weather and amazingly clear skies of early summer continue in northern Arizona. It won’t be too long before the rainy season begins and it will be cloudy more often than clear. Best to take advantage of the great conditions and grab a few more images of the night sky. An important aspect of a night sky image is getting a good foreground in the composition so we took an evening trip down to Sedona hoping to include some of the famous red rocks in the images.
There is no moon and it won’t rise until well after midnight. But there is enough stray light from the small city of Sedona, Arizona, to bring out a glow on the red rocks in this image.
In the past my only attempts at exposure bracketing were with a film camera and were limited to one or two additional images shot with minor variations in f-stop or shutter speed. Then, when developed, I would select the best image and put aside the others.
All that has changed with digital.
Recently I had a chance to explore a slot canyon in northern Arizona. Typical of many slot canyons is the significant variation in light from very deep shadows to brilliant sunlit canyon walls. My best images in these slot canyon have always been compositions that minimize this large variation. But with automatic exposure bracketing and the many available software packages to process the images it was time to give HDR a try.
With just a few images and using Photomatix HDR software I was able to bring out the subtle colors in the deep shadows of the lower canyon wall while capturing the more brilliant colors in the sunlit upper wall.
A second HDR image is able to capture both the well-lit areas and the shadows as twilight approaches over Lake Powell north of Page, Arizona.
The satellite flyby tables (mentioned in a previous post) indicated that there would be a favorable pass of the International Space Station this evening. The ISS would pass by Saturn, Mars, and Venus in the course of a minute or two in mid evening.
I wandered out to the Kachina Wetlands hoping to get good star and planet reflections in the water. It had been windy all day but by evening the wind had diminished and the water was smooth and glassy. Perfect for reflections.
It’s a tradeoff when it comes to shutter speed when imaging a transit of the ISS. A longer exposure will produce a longer track of the ISS while a shorter exposure will result in sharp points for the stars instead of blurred tracks. After a few test shots I decided that 20s was about right. Below are two images of the ISS. The first includes a very bright Venus near the horizon as well as its reflection with the ISS moving below the planet Mars (above and left of the track).
The second image was taken as the ISS was descending into the northern sky with the San Francisco Peaks in the background.
While setting up for the ISS transit I was saddened by the view of the Schultz Wildfire burning in the San Francisco Peaks. This fire has already burned over 14000 acres and is only partially contained. Many trails and forest service access roads have been destroyed by this fire. And, yet, the glow in the evening twilight and its reflection was fascinating.
I have been having a lot of fun taking sky images lately. The newer DSLR cameras (and especially the full-frame cameras) can really push the ISO settings making it easier to take astronomy images with short exposures. The short exposure limits the trails that the stars will make and gives an overall sharper appearance.
This image was shot at ISO 6400, 15s, f/4.0, 28mm focal length. At full zoom, there is only a hint of star trails.
The lights along the horizon add interesting texture to the image but even though they were fairly dim the 15s exposure resulted in far too much brightening. After experimenting a bit, I decided to place a credit card in front of the lens blocking the street lights for about 12-13s, then pull it away for the last few seconds. Overall, it did a pretty good job attenuating the street lights but there is also a dark area in the sky just above the lights.
What I should do is get a better neutral density gradient filter that I can slide up and down rather than the screw-on filter that I have now. Then I wouldn’t have to resort to credit card tricks!
Here is another example of what modern DSLR cameras can do. This was taken with the same settings as the image above. Even with a 28-mm wide angle lens, the camera is able to resolve the Andromeda Galaxy which is over 2.5 million light years distant.
My interests include photography, mountain biking, skiing, trail running, and weather. So that is what I will talk about.
For starters, here is a recent photograph taken mid-evening. Down low on the right is the planet Venus. High up near the top is Mars (reddish orange) next to the star Regulus (blue-white). The streak in the upper left is the still-classified USAF X-37B space plane. It looks a bit like a smaller version of NASA’s Shuttle.