In article ,
David Taylor wrote:

On 04/05/2017 17:24, Tony Cooper wrote:
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I download after every shoot and format the card in-camera.

After formatting the card, check it in h2testw:

https://www.heise.de/download/product/h2testw-50539

There is an English menu.

The re-format in camera.

I discovered a fake card with that one. Only happened me once but it was
annoying...
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teleportation kills