Linhof fresnel - what side is the groove side ?

[lphong]

Greetings, I have received a Linhof 4x5 fresnel screen for my MT 2000. The groove side of the fresnel is to be interfaced with the photographer side of the groundglass. The two sides of the fresnel look similar so it's difficult to tell which side is the groove side. The perimeter area around the border on one side is larger than the one on the other side though. Is the side with the larger border the groove side ? Many thanks.

lphong (new to large format)

[mpirie]

The smooth side of the fresnel should face out to the photographer. The lens side (rough with concentric rings) should be next to the ground glass.

Mike

[lphong]

Thanks Mike. My problem is that with the Linhof fresnel it is not visually obvious that one side is smooth and the other is rough. I can see concentric rings on both sides. The sole difference between the two sides that is discernible is the width of the border area.

[E. von Hoegh]

One side will have raised concentric rings. They are very fine, use your focussing loupe to find them.

[lphong]

Thank you. Now I can identify the groove side with the loupe.