From Gray Mouse to Hubble Star Photographer
The authors are no strangers to astrophotography. Already in 1995 Bernd Koch published the "Handbook of Astrophotography" (Springer); In 2002, Axel Martin followed suit with his "Astrophotography in Five Steps" (Oculum). The remarkable level of these works already showed that the difference between amateur and professional astronomers is becoming increasingly blurred – the latter, too, only cook with water.
In fact, the technical means are almost identical in both camps: CCD cameras and digital image processing. The difference lies more in the quantity: the pixel numbers of the CCD arrays on large telescopes are probably not reached so quickly on home telescopes. Interestingly enough, today's "amateur pictures" are hardly seen. There is also a new class of device that promises everyone fascinating success: the digital single-lens reflex camera (DSLR). This allows you to take high-quality color photos of celestial objects with one shot – without the annoying superimposition of luminance and color channels (keyword L, R, G, B). It was this new, relatively inexpensive technology that persuaded many to start astrophotography.
So the authors had to cover a wide field – and they did it with care and great expertise. You can feel the many years of experience. Both apparently actively experienced the change from analogue to digital astrophotography: from the tedious beginnings with hypersensitized film to the first CCD cameras (e.g. the legendary ST-4) to the modern DSLR. Many things are certainly simpler today – but also more varied. A good example is editing the recordings on the computer. Here, too, the authors, like many others, went to the classic "Photoshop school". Whereas galaxies used to appear in amateur images only as inconspicuous "grey mice", today they shine in impressive colors and high resolution - the Hubble Space Telescope (HST) sends its greetings. A modern CCD recording, made with an 8-inch, for example, and processed digitally with standard software, is a whole lot better than an analog one with the Mt. Palomar 200-inch from the 1960s (nostalgics may see it differently). What progress! Amateur astrophotographers are now at the forefront - the days of tinkering are finally over. However, in order to produce "beautiful pictures", they need the latest technical information.
The book by Martin and Koch offers exactly that. It's a treasure trove full of tips and tricks, data and use cases. To say it straight away: The large-format, 368-page work, enriched with many tables and graphics, is a must for anyone who is seriously involved with digital astrophotography or wants to deal with it. So is it also suitable for beginners? Let's take a closer look at the content.
The first chapter covers the camera and the basics of digital photography. The reader learns everything about "binning", "blooming" or "CMOS chips" - unfortunately many terms are from English, which can hardly be avoided due to international use (the German versions would sound strange, such as "blooming semiconductor wafers"). In general, a certain basic knowledge of physics can certainly not hurt to understand things such as "quantum efficiency" (the glossary in the appendix is useful). The second chapter is about the optics. In addition to the camera, telescopes are discussed above all; their properties and errors, as well as the necessary accessories (filters, adapters). It continues with the mount: from the simple photo tripod to the installation of telescopes and protective structures. These instrumental chapters show that the book is far more than a mere presentation of astrophotography.
The main chapters on the operation and use of the camera (CCD, DSLR) follow. Anyone who has not yet been able to distinguish between "dark image" and "flatfield" - and in particular the order in which they are used - will be given comprehensive information here. Important topics such as focusing, tracking and exposure time are also de alt with. My impression: nothing is missing. The last factual chapter is about digital image processing - ultimately the key to the "pretty picture". The computer with its software is like the modern witch's kitchen. All tricks are used here, after all you want to present something decent after all the effort. The authors reveal all their "secret knowledge"!
What can come out of this is shown under "Image examples". It contains an impressive collection of astrophotographs, although - with one exception - standard objects are presented. This also makes sense, because the reader should compare his own pictures with it. The only exception is the famous "Hubble Deep Field". The comparison between HST and a C-14 is quite interesting. If this material is not enough for you, please refer to the attached CD-ROM. It also contains a collection of image editing programs (freeware/shareware).
Conclusion: The work is a well-written textbook that you certainly won't read through in one go, but will refer to it again and again on individual topics. Unfortunately, an index is missing. Nevertheless, it is suitable for both beginners and advanced users. However, one problem might be the rapid development in the field of digital astrophotography. This has already made some books "look old" quickly. However, I think that due to the abundance of material, and above all the thorough presentation of the timeless physical basics, a longer half-life is to be expected.
Admittedly, the international competition among astrophotographers is fierce. Most of them don't hoard their pictures in photo albums, but proudly present themselves on the Internet. However, the representations are sometimes heavily manipulated when the digital "sorcerer" runs away with his imagination again. It used to be thought that images were "objective", but in the age of image processing this is questionable. Here, too, a look at the textbook helps - and if necessary the honor of the astrophotographer.
Interestingly, there is also increasing competition between amateurs and specialist astronomers. While the latter tended to stay away from the production of "pretty pictures" for a long time - with the exception of HST pictures - the professionals are now discovering a new field. Almost decommissioned large telescopes such as the 3.6-meter CFHT in Hawaii are equipped with oversized CCD cameras in order to shoot pictures that attract the public - after all, tribute must be paid to the taxpayer. Whatever the case, competition stimulates business – and the "amateurs" get involved.
