What is a deepscape you might ask?
Most of us are aware of nightscape / Milky Way landscape photography. Those are forms of astrophotography that use super wide-to-wide angle lenses capturing usually the Milky Way — but sometimes the winter sky as well — with the landscape as foreground features. Often these are single exposures in dark locations with iconic or recognizable landscapes, buildings, etc. to ground the image. Instead of single exposures, you can also use a star tracker* to shoot the Milky Way in order to gather more detail and reduce the noise and then blend that image with the landscape shot that was taken prior to or after the Milky Way session. Deep sky object (DSO) astrophotography, often involves telescopes or super long telephoto lenses. The object being photographed can be quite beautiful isolated in a field of stars or the inkiness of space. Deepscape astrophotography marries these two types of nighttime photography. One uses a medium to long telephoto lens to photograph a DSO, typically as it rises or sets over the landscape. The DSOs are often quite faint necessitating a star tracker in order to gather as much detail as possible and have relatively clean images for further processing. Normally one would take the landscape photograph during blue hour before the sky session or after, before the sun rises. The idea is to show true-to-life the scale of a deep sky object is relative to the landscape below it. In order to stay true to the concept, the DSO image must be taken with the same focal length as the landscape image. This is different than so-called dreamscape images which are usually composites of some space object with some beautiful (and often improbable) landscape which thereby renders the image as looking not quite right, fake. Deepscape images reveal, however, the true size of an object relative to our world. In other words, if our eyes were as sensitive as our camera sensors are, then you really would see that particular space object hovering above the horizon, the way it is presented in a deepscape photograph. The whole point of deepscape astrophotography is to reveal not to confuse (and bamboozle!).
The image you see here is comprised of 180, 30 second exposures of a nebulous cloud structure called the Rho Ophiuchi Cloud Complex near the edge of Scorpio, the scorpion constellation. The landscape was a single capture just prior to dawn the next morning. Both were taken with the same Pentax K-1 astro-modified** DSLR with a Rokinon 135mm f/2.0 lens. The star tracker used is an iOptron Sky Guider Pro with counterweight. Each sky image reveals little initial detail (see example below). But stacking and processing will change that.
The 90 minutes worth of sky images were uploaded into a program called Astro Pixel Processor that I use to align and stack images for DSOs. I typically take calibration files***, but I did not do so for this particular session. APP outputs one file that I load into another program called PixInsight. This is the program that I use for virtually all of my astrophotography processing. It is a complex, function-driven application that allows me to maximize details such as the nebulous clouds you see here without blowing out the stars, increasing noise, etc. I won’t go into the details of this workflow here but suffice it to say, that once I am satisfied with the sky image I output one file. This is further processed in both Photoshop and Lightroom and the finalized sky image can be seen below. The processing of the landscape was relatively simple accomplished in Lightroom (see image below). I opened these two files in Photoshop and used the sky replacement tool to blend in the sky above the mountains. Final adjustments are done in both Photoshop and Lightroom.
A night’s worth of work, followed by several hours of processing, finally yields a true-to-scale image, wedding the ethereal wonders of the sky with the solidity of earth below, all in proper proportion and alignment to each other.
*Star tracker: Once properly aligned with the North Star, a star tracker will rotate in the same direction and at the same rate as the earth rotates. This permits long exposures and pin-point stars.
**Astro-modified cameras: This involves removing the UV/IR blocking filter that sits in front a DSLR or mirrorless camera’s sensor and replacing it with a filter that permits visible light, plus an increased amount of hydrogen-alpha light, which abound in the galaxy and is reddish in hue.
***Calibration files: There are three basic kinds and whilst they are essential for DSO astrophotography, they are less so for both nightscapes and deepscapes. Generally, they remove unwanted noise, hot pixels, vignetting and dust spots from your final outputted file.
Words and Images Jeff Clay