diff --git a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
index 7ef24e1..2cabf9c 100644
--- a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
+++ b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
@@ -225,4 +225,10 @@ On simple optical printers the only lateral adjustment is of the lens (rather th
 This is geometrically adequate.
 
 But the J-K adjustments are even too flimsy for a lens.
-It helps, after they are set, to gently tap the lens, so it finds a stable position, and then to readjust if necessary, etc., etc.
\ No newline at end of file
+It helps, after they are set, to gently tap the lens, so it finds a stable position, and then to readjust if necessary, etc., etc.
+
+## EXACT 1:1
+
+The lateral movements of the lens, the to-fro movements of the lens and camera, and a tilting of the camera (if necessary) allow the optical printer to be set for exact 1:1 reproduction.
+Then the printed image is the same size and in the same position as the original image.
+If the printer lacks a tilt adjustment the camera may be shimmed.