r10526: improve print-magnification with crop function

[cl-photo.git] / fov.lisp

diff --git a/fov.lisp b/fov.lisp
index 211820af13e616d9d5b83818b908f84e47eb8a15..6fec649da285882846259180f3037c6fdaf74cd6 100644 (file)
--- a/fov.lisp
+++ b/fov.lisp
@@ -208,3 +208,14 @@ Returns: focal-length object-distance image-distance magnification bellows-facto
   "Returns the bellows factor, the ratio of effective aperature to actual aperture."
   (1+ (magnification :focal-length focal-length :object-distance object-distance)))
 
+(defun extension-tube (focal-length &key original-object-distance new-object-distance original-image-distance
+                                        new-object-distnace original-magnification new-magification
+                                        extension-length (units :feet))
+  "Computes the parameters for using extension tubes.
+Requires: 1. original-object-distance, original-image-distance, or original-magnification
+          2. new-object-distance, new-image-distance, new-magnification, or extension-length
+Returns: original-object-distance, original-image-distance, original-magnification,
+         new-object-distance, new-image-distance, new-magnification, extension-length."
+  )
+
+