IQ180 diffraction at F16?

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Hi all, I am purchasing an IQ180 but have become aware of diffraction issues at F16 ? I often shoot table top -still lifes in the studio and require depth of field. How serious an issue is this diffraction ? What can be done about it?
I'll be using Mamiya 645 Af with Mamiya 80 mm Sekkor lens. I currently use the P45 back. Thanks for any comments. Max