When Zeiss Ikon was founded they were faced with not only sorting out which models would be continued into the Zeiss Ikon catalog from the pre-Zeiss lines, they had to remainder out existing stock which had been made before the merger. Ernemann had a line of folding plate cameras that were marketed under the name Heag, which stood for Heinrich Ernemann Aktien Gesellschaft, although they were not always referred to as Heag in Englsih advertising.
The Heag line included basic cameras through the most full featured, as well as stereo and tropical models, some with leaf shutters, some with focal plane shutters, and even some with both. They stretched in size from small to large, and were offered over about a 20 year period with model numbers ranging from one to sixteen, usually expressed in Roman numerals.
It's not clear whether they were ever manufactured by Zeiss Ikon, or whether the remaining stock was just slow to sell under the competition from all of the other folding plate cameras in the catalog. But it appears that at least some of the models were listed as late as 1931.
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