Acknowledgements: The DELTA project wouldn’t have been possible with the naysaying of experienced lens collectors; the death of film; the opposition of my wife; the embezzlement of shady eBay sellers and Japanese auction agents; the re-branders; the same 50/3.5 seen in a thousand guises; the unhelpful attitide of extant manufacturers who jettisoned their history without a backward glance (Schneider, Rodenstock et al); the corporations who swallow the legacies of decades without concern for their preservation; the disregard of librarians and archivists who no longer value photographic publications; the copyright laws prohibiting reproduction of adverts advertising things no longer made, once made by people and companies that no longer exist; the museums failing to digitise their collections and refusing to grant access to material rotting unseen in their basements; the sheer bloody-mindedness of Agfa serial numbers; the arrogance of those who have previously written about alt.lenses and imagine their sayings to be unalterably definitive, despite being patently erroneous;  widespread dementia and death befalling a generation of those with inside knowledge of the industry; widespread withering of the information internet and the rise of regurgitated AI gobbledygook; the majority of used camera dealers who regard these lenses as pointless relics and have no interest in deploying them as taking lenses and regard their slow-moving stock as an irritation; clueless marketing people devoid of specific product knowledge; an overwhelming majority of photographers apathetic about the benefits and possibilities of alt.lenses; the publishers who failed to express an interest in a book deal; the army of DIY botchers who took their lenses apart and didn’t know how to put them back together again; a postal system that loses packages as a normal happenstance;  and all the fungus. Against this tide stand we few. You know who you are. Thank you.