diff --git a/focus.md b/focus.md
index 2c84b1e..b4c96f7 100644
--- a/focus.md
+++ b/focus.md
@@ -12,6 +12,17 @@ f01600017904 00001983000066000000410000 d70155
 | 11 | 09 when in DMF and manually focusing, 01 normally, 41 autofocus active |
 | ... | ??? |
 
+## Autofocus
+sample message:
+```
+f02700018004 000019830000660000804100002f090a1f 020283 848345f2 3e7f53030000 a80655
+```
+| Byte | meaning |
+| ---- | ------- |
+| 18 | controls if focusing in or out |
+| 21 | focus speed range 81-88 |
+
+
 ## Info (from Lens to Body)
 Sample message:
 ```