Hi, I'm having an issue with my CLS 66 diffuser head on a Durst 601. When I focus on the negative, the borders of the print go blurred.
Is it normal that you can't have sharp borders without using an easel ?
The alignment is ok, there are no reflections, the lens and lensboard are fine. The Sivobox is the correct one. The only way to have sharp borders is to focus on the negative holder, leaving the negative out of focus.

apug1.jpg
apug2.jpg

I can use an easel as a shortcut but I'd like to know if it's a common problem or if I'm missing something basilar here.
Any help will be appreciated, thanks in advance guys !