SD cards losing memory?

[sanclemente]

I'm using a Nikon D5000 and aperture on an iMac. For some reason, the memory on my SD cards is disappearing. I have two 8GB cards that both have all the pictures deleted from them, but still say roughly 7GB of the 8GB are in use. What is the cause of this and what is the solution?

 

[FrankieTDouglas]

Have you formatted them in the camera?

 

[jackerin]

If you are copying them from the card in the Finder and then moving the images to the trash, don't forget to also empty the trash.