Of all the reference books about Leica, I give three thumbs up to Erwin Puts’s Leica Compendium. This is so far the best reference about Leica. As the subtitle of this book suggests, it is truly a book about the company, the cameras and the lenses. This is also a massive and comprehensive attempt to give a full account of everything about Leica in totally 610 pages, thicker than the Yellow Pages. The one I currently own is the second expanded edition, published in August 2011. The book was sold out fast. It seems several months ago there was a latest edition available for pre-order, but I am not quite sure whether it is the third edition (with minor updates) or only a re-print.
Leica is a legendary name in 35mm photography and there must have been numerous books about it. However, I have not read too many. This is how to learn about these reference books about Leica: do a search on Amazon and find what relevant titles are. Of the current titles, you must not miss Leica M, Advanced Photo School written by Gunter Osterloh. According to the book cover Osterloch has been the product manager at E. Leitz Wetzler and Leica Camera AG. From 1993 to 2002 Osterloch also directed “The Leica Academy” which conducts activities with Leica equipment. You can also read Osterloch’s blogs on Pixiq as he is one of the contributors. Leica M, Advanced Photo School is in its second edition. It contains many valuable technical information about the M system although all the digital models are not dealt with. One interesting section in this book is about proper handling of Leica M cameras. Even this is entirely related to Leica M film cameras, you can apply the skills to the current digital Ms which are built in similar form factor. All in all, I agree this is one of the excellent books written by a Leica insider.
This is why I give great full credits to Erwin’s Leica Compendium because it covers all Leica M models. I particular like his comments on lenses. I bought the book directly from LFI at the price of €78 plus €20 shipping in August 2011. It was soon sold out and greeted by great applause, but you may find this edition is now available by some resellers on eBay asking for double or triple of the original price. This is insanely high but you know this limited edition is now value-added.
I would like to support Erwin Puts directly instead of supporting a profit maker.
Here is the deal. If you want to know more about not only the technical aspects (such as studying the optic quality from the MTF graphs) of Leica, read Leica Compendium. This hugh book is now available again for order from LFI at the same price as that of a year ago. This edition is called new extended edition, probably with some minor amendments (as seen from the book screenshots).