diff --git a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
index 723f812..acb0961 100644
--- a/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
+++ b/NOTES_ON_OPTICAL_PRINTER_TECHNIQUE.md
@@ -106,4 +106,21 @@ But for each position of the camera (except the 1:1 position) there are two corr
 The printer gate may hold 8mm film and the printer camera 16mm, or vice versa.
 With a `M = 2` setup an 8mm original frame is photographed onto a whole 16mm frame.
 With an `M = 1/2` setup a whole 16mm original frame is photographed onto an 8mm frame.
-Conversion between any two film gauges is possible this way, provided the frames have the sane proportions, as 8mm, super 8mm, 16mm, and some 35mm do.
\ No newline at end of file
+Conversion between any two film gauges is possible this way, provided the frames have the sane proportions, as 8mm, super 8mm, 16mm, and some 35mm do.
+
+## BLOWUP SHARPNESS
+
+A 16mm picture of a flea can be just as sharp as a 16mm picture of an elephant.
+But a 16mm picture of an 8mm picture cannot be expected to be as sharp
+as a 16mm picture of a 16mm picture.
+Pictures differ from things in having very limited detail.
+The 16mm blowup, even if it preserves all the pictorial detail of the 8mm original, spreads it out, so the blowup is less sharp absolutely than the original.
+
+Under extreme magnification--a microscope objective could be the printer lens--pictorial detail is diffuse and the underlying natural thing, the emulsion, is all that could be photographed sharply.
+But the grains are too small to be sharply imaged with light. 
+Here even the natural thing has been photographically exhausted.
+
+An 8mm original blown up to 16mm and projected will appear sharper than the same 8mm original optically printed onto 8mm and projected.
+If the blowup optics are good this is even true when the 1:1 printing is by contact.
+Likewise for 16mm to 35mm. 
+(This is all due to the print film being in effect twice as sharp and half as grainy in a bigger frame.)