Next I took 10 of the brightest images and Stacked them (additive).Photographing star trails can be challenging but also rewarding. But I wasn’t happy with the result – the foreground still wasn’t bright enough. And I made the same adjustment to the result in Picasa as I showed in Screen Shot 1. But if you specify a divisor of, say 5, then you are averaging AND effectively increasing the brightness by about 1 stop. If you have 10 images and specify a divisor of 10 then you are simply averaging. Fortunately Image Stacker has an option to stack and average. The brightest pixels may also be noise! Using averaging reduces the noise significantly – but it will not remove “hot” pixels we will address those later. Remember that “brighten mode” (Lighten in Photoshop) does not brighten anything – what it actually does is select the brightest pixels at each location from each of the images in the stack. when the trucks were lighting them), and combined them using additive stacking to brighten them and averaging to reduce the noise. I found all the brightest shots of the cliff face (e.g. I want the cliff to pop a bit better, so my next course of action was to work on improving the foreground. There really was no reason to include the first shot. One obvious problem with the result is that the combination of the early short exposure with the sequence of shots left a gap. (Note: StarStax is a program that supports Mac, Unix and Windows and works well, too!) The stacking action takes about the same amount of time, but is more versatile and can even use raw images. I could have used the Star Circle Academy Stacking Action in Photoshop instead and the result would have been identical. My option for Image Stacker was “Brighten” mode. I then dragged and dropped all the exported (JPG) images onto Image Stacker which took about 3 seconds per image – less than two minutes to create a result. In this case I didn’t have to do any white balance adjustments because I had preset the camera to approximately 4100K. I could have done all these things with ACR (Adobe Camera Raw) or Lightroom. I cloned the recipe to all the photos and exported them into a “RedRockEast” folder in a temporary directory. I exported in Landscape style which adds a slight saturation increase (Photoshop Saturation and Vividness) and modest sharpening. I used Digital Photo Professional to pull up the images, applied a bit of contrast enhancement, a slight exposure increase (1/3 of an f-stop), and a very slight noise control over the entire image. I downloaded all the images from my card to my Incoming folder which is organized by date. Photo 3: Collage of some of the photos used in the stack.
I did not include that last shot in the stack. The last shot was taken as twilight approached is too bright to use because the sky is losing contrast and the light on the cliff is looking flat. Note how the light changes from passing trucks! You can also see the counter-clockwise rotation of the Milky Way. I pulled out my reclining beach chair, a sleeping bag and slept while the camera clicked.
I set my camera to record in RAW and my interval timer to take 5 minute, 59 second exposures every 6 minutes. Changing the aperture from f/2.8 to f/3.5 drops the light by about 33%, so I increased the exposure from 4 to 6 minutes. Starting with an exposure at 1 minute, 2000 ISO f/2.8 as a starting point I calculated an ISO 500, 6 minute exposures at f/3.5. Here is how: A 1 minute exposure at ISO 2000 is equivalent to a 4 minute exposure at ISO 500 (500 is 1/4 of 2000). It is no different from changing a daylight exposure from 1/200 of a second to 1/100 of a second. Those of you who don’t do much night photography are thinking “Whoa from 30 seconds to 1 minute is a huge difference.” But no, it’s not. I needed to at least double the exposure to 1 minute. The other is that the exposure (ISO 2000, f/2.8, 30 seconds) was under exposed. Photo 2: First, image: ISO 2000, f/2.8, 30 seconds.Īfter taking the first image, I realized two things: one is that the trucks passing were providing helpful light on my foreground – but not always illuminating the entire thing.
0 kommentar(er)
