Differences

This shows you the differences between two versions of the page.

--- doc:appunti:hardware:canon_s120 [2019/03/22 10:19] – [Manual Focus] niccolo
+++ doc:appunti:hardware:canon_s120 [2020/10/31 08:33] (current) – [Exif Tags] niccolo
@@ Line 18: / Line 18: @@
 ^ Exif.CanonCs.AFPoint  | Auto-Focus frame setting. Exiv2 library is incomplete or misleading, here it is the true meaning of values:\\ ''(0)'' => **None** (Manual Focus)\\ ''(16390)'' => **Face AiAF**\\ ''Manual AF point selection'' => **1-point**  |
 ^ Exif.CanonSi.SubjectDistance  | Subject distance, as per manual focus or Auto-Focus. The number seems to be the **distance in cm**, where **infinity** is reported as **6553**.   |
+^ Exif.CanonSi.0x0014  | According to Exiftool source code, this should be **FocusDistanceLower**, where the //SubjectDistance// is actually the **FocusDistanceUpper**. It is supposed that the camera knowns not the actual subject distance, but just two distances where the focus point is in between.  |
 ^ Exif.Canon.0x0027  | This multi-byte tag contains, among others, **Dynamic Range Correction** and **Shadow Correct** settings. Byte 4 (counting from zero) is a bitwise representation, under investigation.\\ Byte 16 is the Dynamic Range Correction:\\ 0 => **Off**\\ 1 => **Auto**\\ 200 => **200%**\\ 400 => **400%**  |
 ^  ISO Speed  ^^
@@ Line 84: / Line 85: @@
   * If the **Safety MF** option is **On** (see the [MENU], camera tab):
     * Move the **focusing frame** (orange rectangle) tapping the touch screen.
-    * Press **halfway the shutter button** to **refine the focus**. Warning! The instruction manual talks about //fine-tune//, but it is not clear how much can be this fine tuning. Some users reported that a manual set of one meter, was corrected by fine-tune to infinite, beacuse no objects to be focused were in that range.
+    * Press **halfway the shutter button** to **refine the focus**. Warning! The instruction manual talks about //fine-tune//, but it is not clear how much can be this fine tuning. Some users reported that a manual set of one meter, was corrected by fine-tune to infinite, beacuse no objects to be focused were in the one meter range.
 ===== Safety Shift =====
+**Safety Shift** is an option that interferes with manual settings in **Tv** and **Av** modes.
+Pressing the **shutter button halfway** will show the aperture value or the shutter speed **selected automatically to obtain a standard exposure**, if such exposure cannot be obtained, the value is displayed in **orange color**. But if **Safety Shift** is enabled, the manually selected value (aperture or speed) will be corrected and displayed on the screen. To enable this option, press the **%%[MENU]%%** button and search the **%%[Safety Shift]%%** into the //camera tab//.
+===== Neutral Density Filter =====
+In photography, a **neutral-density filter** is a filter that **reduces the intensity of all colors of light** equally. The purpose of a neutral-density filter is to **reduce the amount of light** entering the lens, **allowing combinations** of aperture and exposure time that would otherwise produce overexposed pictures.
+For example you can use it to allow an **high aperture value** and get a **lower depth of field**.
+====== Python Script Download ======
+Here it is a Python script to decode Exif metadata from photos taken by the Canon PowerShow S120: **{{.:canon_s120:canon-metadata.txt|canon-metadata}}**.
+====== Web References ======
+  * **[[https://www.exiv2.org/tags-canon.html|Exiv2 - Canon MakerNote Tags]]**
+  * **[[https://www.dpreview.com/forums/post/35260903|Wow.... focus distance reported in EXIF???]]**
+  * **[[https://photo.stackexchange.com/questions/105977/what-is-focus-distance-lower-upper-and-how-is-it-different-from-depth-of-field|What is “focus distance lower/upper” and how is it different from depth of field?]]**
+  * **[[https://www.dpreview.com/forums/post/51962463|Distance in EXIF]]**