Differences

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--- doc:appunti:hardware:olympus-e-m10:manual_lens [2022/11/15 12:58] – [EXIF data] niccolo
+++ doc:appunti:hardware:olympus-e-m10:manual_lens [2025/11/10 17:38] (current) – [Meike 25mm f1.8 Specs] niccolo
@@ Line 15: / Line 15: @@
 The body of the lens is build from **metal**, so it feels sturdy and solid. The aperture ring does not have mechanical feedback over the stops: it turns smoothly from **f/1.8** to **f/16** with a little friction, so it should not move inadvertently.
 The focus ring also has a little friction that should prevent unwanted moves, the external element does not rotate on focusing, so you can mount e.g. a **49 mm polarizer filter** and it will **not rotate** on focusing. A depth of field scale is printed on the lens body (but it is **totally wrong**, see below).
+===== Meike 25mm f1.8 Specs =====
+Lens specification as reported on the [[https://meikeglobal.com/en-it/collections/meike-lens-1/products/2518m43|vendor page]]:
+^ Focal Length            | 25 mm  |
+^ Maximum Aperture        | f/1.8  |
+^ Minimun Aperture        | f/16  |
+^ Diaphragm Blades        | 9  |
+^ Filter Size             | 49 mm  |
+^ APS-C Visual angle      | diagonal 61° horizontal 50° vertical 35°  |
+^ Lens construction       | 7 elements in 5 groups, multi-layer coatings  |
+^ Minimun Focus Distance  | 0.25 m  |
+^ Diameter                | 60.5 mm  |
+^ Length                  | 40.9 mm  |
+^ Product Weight          | 190 g  |
 ===== Modes M, S, A and P =====
@@ Line 163: / Line 179: @@
 ===== Depth of field =====
-The **[[wp>Hyperfocal distance|hyperfocal distance]]** is the distance to focus to have the max depth of field at the given aperture. All objects in the DoF range are into an "acceptable" focus. The DoF far limit is inifinity and the near limit is HD/2.
+The **[[wp>Hyperfocal distance|hyperfocal distance]]** is the distance to focus to have the max depth of field at the given aperture and focal length. All objects in the DoF range are into an "acceptable" focus. The DoF near limit is half the hyperfocal distance, the  far limit is inifinity.
+^  Using a 25 mm lens on a Micro Four Thirds sensor  ^^
 ^ f/value  ^ Hyperfocal Distance  ^
 | f/1.8  |  23.41 m |
@@ Line 174: / Line 191: @@
 | f/11   |   3.71 m |
 | f/16   |   2.63 m |
+==== Depth of field in portraits ====
+Here is an handy table to know the depth of field when shoting portraits. I think that the wider apertures of the Meike (f/numbers below 4.7) are extremely effective starting from medium or more distant shots. With close-ups, care must be taken that not all parts of the head may be in focus.
+^  Framing with a 25 mm lens, MFT sensor (50 mm eq.)  ^^^  Depth of field  ^^^
+^ Shot type  ^ Height dim.  ^ Focal length  ^  f/1.8  ^  f/5.6  ^  f/16  ^
+| Choker  (from eyebrows to mouth)  |   20 cm |   42 cm |    1 cm |    5 cm |   13 cm |
+| Close-up  (shoulder and head)     |   40 cm |   84 cm |    6 cm |   19 cm |   58 cm |
+| Medium shot (from the waist up)   |   70 cm |  146 cm |   18 cm |   59 cm |  231 cm |
+| American shot  (mid thigh)        |  120 cm |  250 cm |   54 cm |  189 cm |    49 m |
+| Full shot (head to toes)          |  200 cm |  417 cm |  153 cm |  687 cm |       ∞ |
 ===== EXIF data =====
@@ Line 194: / Line 223: @@
 There are several vendors of manual lenses that can be mounted on cameras of well known manufacturers, such as Olympus, Canon, Nikon, etc. They offer good quality for a fraction of the cost of the original lenses. Almost all are Chinese manufacturer, which have reached very high standards of quality. Here a partial list of some of them, please follow the link to **sponsor my affiliate programs**.
-  * **[[https://www.amazon.it//review/R37KAL7C2ON8XB/ref=cm_rv_eml_rv0_rv|My review of the Meike 25mm f/1.8 on the Amazon site]]**
   * **[[https://meikeglobal.com/|Meike]]**
+  * **[[https://www.pergear.com/?ref=2BPZm|Pergear]]**
   * **[[https://7artisans.store/?ref=FRFtTFVb|7Artisans]]**
-  * **[[https://7artisans.store/products/25mm-f1-8?ref=FRFtTFVb|Manual lens 25mm f/1.8 by 7Artisans]]**
-  * **Risespray**
   * **[[https://ttartisan.com/|TTArtisan]]**
+  * **[[https://www.amazon.it//review/R37KAL7C2ON8XB/ref=cm_rv_eml_rv0_rv|My review of the Meike 25mm f/1.8 on the Amazon site]]**
+  * **[[https://www.pergear.com/products/pergear-7-5mm-f2-8-fish-eye-manual-focus-fixed-lens?ref=2BPZm|Pergear 7.5mm F2.8 fish eye]]**
+  * **[[https://7artisans.store/products/25mm-f1-8?ref=FRFtTFVb|Manual lens 25mm f/1.8 by 7Artisans]]**