The Zeiss Ikon Tenax I (570/27) is a 35mm viewfinder camera that produces 24×24mm square negatives on standard 35mm film. It was a compact, fixed-lens model positioned in the lower-to-middle tier of Zeiss Ikon's pre- and post-war 35mm range.

Sales data for the Tenax I is extremely thin: a single recorded UK auction hammer result from 2003 saw an example sell for £178. With only one historic data point and no recent comparables, today's value is difficult to estimate reliably, and any current price would depend heavily on cosmetic condition, shutter function and completeness.