I’ve written a long article about radioactive lenses, explaining everything in detail. This placement of the radioactive component makes it safer for both the user and the camera because the radiation level at the rear of the lens is barely noticeable above the background level. Radioactivity is mild, and very ‘favourably’ placed – radiating mainly from the front of the lens towards the subject, and not from the rear element towards the user. Geiger counter registering 1.19 uSv/h for front of Mamiya Sekor 58mm f1.7 M42 Is it dangerous? Exakta and Argus versions don’t contain thoriated glass – suggesting that there are different optical specifications between radioactive M42 and the non-radioactive versions. Mamiya Sekor 58mm f1.7 M42 is mildly radioactive – indicating that lens includes thorium-containing glass. Mamiya Sekor 58mm f1.7 M42 Lens radioactivity This camera had a unique mount, not used on any other camera system, therefore adapting is difficult without lens modification. The third version is in the form of Argus-Sekor 58mm f1.7, which Mamiya made for Argus between 1962-1966.

M42 version is also the rarest because Mamiya only made it for two years. It came with the M42 version of the Mamiya Sekor 58mm f1.7, containing radioactive lens elements – meaning a change in the optical design had occurred between the first and second versions. In 1964 Mamiya launched a successor to the Prismat – Mamiya/Sekor CP, also known as the CWP in the USA. This camera used an Exakta mount therefore, the first version of the Sekor 58mm f1.7 can easily be adapted to modern cameras using the widely available Exakta adapters.

Mamiya Sekor 58mm f1.7 F.C., released in 1961, alongside the Mamiya’s first production SLR camera – the Mamiya Prismat NP. History and versions Mamiya Sekor 58mm f1.7 F.C. Mamiya Sekor 58mm f1.7 is another vintage lens from the 1960s – having a somewhat rare focal length and aperture combination, producing soft bokeh and strong object separation.

Mamiya 7 ii sample images