I’ve been imaging the sky for almost thirty years. First, I tried with photographic film for a few years. This experience was frustrating. You guided (manually) for a long time at sub-zero temperatures on the countryside to get two or three images per night. The next morning, you had to develop the film and many times, at home, you discovered that the guiding was not perfect and then you had star trails instead of pinpoint stars or any other problem on the image ruining the negative. It was really difficult to obtain good results with film.
A few years later, in the early 90s, with the CCD advent, the high sensitivity of the sensors and the quick feedback displaying the image just after acquisition changed the sky imaging forever. Yes, you had to take a computer with you to the field but it was exciting to exposure your sensor for only a few seconds and get really faint objects.
At the beginning, the CCD sensors were tiny and center a faint object on the chip was really challenging. Those primitive cameras had high noise and required a lot of seconds to download the image to the computer. However, thanks to that technology the amateur astrophotographer had access to objects that were photographed before only by the professionals. The Stephan quintet, IFN, faint extensions of planetary nebulas, galaxies arms were now fully available for the amateur. The new limit was beyond the Messier catalog. With a CCD, practically the whole NGC catalog were at your fingertips and other exotic catalogs such as the Van der Bergh entered onto the scene.
The two primitive images below are M104 and M51 galaxies. They were taken when we were starting to take images with a CCD. The camera was a Cookbook CCD with a small TC245 sensor from Texas Instruments. We were surprised by the amazing sensitivity of the sensor.
Today, they are vintage images. However, in the 90s, it was a revolution to see faint structures of galaxies with just a few seconds exposure.
At the beginning, the CCD sensors were tiny and center a faint object on the chip was really challenging. Those primitive cameras had high noise and required a lot of seconds to download the image to the computer. However, thanks to that technology the amateur astrophotographer had access to objects that were photographed before only by the professionals. The Stephan quintet, IFN, faint extensions of planetary nebulas, galaxies arms were now fully available for the amateur. The new limit was beyond the Messier catalog. With a CCD, practically the whole NGC catalog were at your fingertips and other exotic catalogs such as the Van der Bergh entered onto the scene.
At that time, we didn’t know anything about image processing and the first programs were simple and unfriendly. However, in a few years, processing software became very powerful and the amateurs learnt to use it. Soon, we learnt how to calibrate effectively our images and how to apply complex algorithms over them.
When I look back, I feel that each step on the learning curve of astrophotography has been painful. It takes years to master your equipment and to understand the digital processing techniques to extract as much as possible from your images. Many times, things do not work and you feel you are blocked and wasting your time.
However, with perseverance and many sleepless hours, tests, changes and asking for help to friends you always find the way to advance. Once you have learnt the basic concepts and got a stable equipment, you realize of the possibilities of the modern technology and start to obtain interesting images.
Fortunately, the CCD revolution has occurred at the same time that amateurs were connecting our computers to Internet. This fact has played a critical role on the development of the amateur astrophotography on the last thirty-five years. Now, we are interconnected and you can share images and tips, issues and solutions.
Below are two images: a chemical photo of M13 I took with my first telescope, a venerable Vixen 130R reflector when I was a teenager and a recent (2019) CCD image of the same object obtained with a 6303 Kodak sensor and modern amateur gear.
Current image processing techniques, advanced CCD sensors and tracking and pointing accuracy on mounts have made possible to reach this level of deep space astrophotography today. And… this level is available to the amateur.
Today, telescopes are also more affordable, but optics are (more or less) the same than years ago. The actual disrupting change has been the introduction of electronics and the internet
The image on the left below (credits POSS-II/STScI and Lars Karlsson) is a digitalization of the photographic plates obtained with the Samuel Oschin Telescope, a 48-inch (1.2 meter) Schmidt camera placed in the Palomar Observatory. This telescope performed its second photographic survey between 1985 and 2000. This image corresponds to the M13 object area of this survey. The image on the right is a zoom over my M13 image.
Currently, amateurs have access to magnitudes and structures close to those found on the POSS-II survey and can obtain images close to the ones that the professionals obtained with film using 1-2 meter class telescopes.
It is a remarkable fact that amateur astrophotographers have access to this technology to scrutinize the Universe. We should congratulate ourselves for the means available today for us.