Blurry print borders with diffusor head

[alex645]

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.

50126
50127

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 !

[tkamiya]

Yes, it is normal.

When film is sitting inside the neg holder, the cutout of the neg holders are much thicker and in a different plane than the images on the neg. The DOF at the film is really thin. It is impossible to focus both on the negative and the image. Sprocket holes and the imprinting on the negative should be sharp but the borders created by the hole on the neg holder won't be.

When I print with my D2, I have to be careful NOT to include the border created by the neg holder within the image area of the easel - or otherwise, I'll have a blurry border.

[alex645]

Thanks Tkamiya ! As a self-learner looks like a was missing something basic

[andrew.roos]

The masks on the negative holder are useful to eliminate stray light outside the print area so it doesn't bounce around and soften the print. The print border is created by the easel.

[silveror0]

Do I understand you correctly that you're not using an easel? If so, you need to be aware that many papers will tend to curl up some at the edges, which may cause the print edges to blur. There is also a depth of field involved at the plane of the paper and, if exceeded, will cause the image to blur (increasing toward the edge of the image). The blades of the easel will hold down the curl.