Using coins for scale is discouraged as it will require people unfamiliar with them to look up the dimensions or guess, both of which defeat the purpose of the object in the first place. Coins can also reinforce a geographical bias, and some coins' designs are copyrighted.
Ideally, a photograph should include a ruler with the subject (example) or an added scale marking.
SI ("metric") units are the most commonly used worldwide (see meter and centimeter).
I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.
Captions
Droplets of blood
Items portrayed in this file
depicts
copyright status
copyrighted, dedicated to the public domain by copyright holder
copyright license
released into the public domain by the copyright holder
source of file
original creation by uploader
inception
29 November 2007
exposure time
0.125 second
f-number
2.8
focal length
6.1 millimetre
ISO speed
200
media type
image/jpeg
instance of
photograph
checksum
3f4705dc8badce3aa9411fc47377e388bde072be
determination method: SHA-1
data size
93,568 byte
height
480 pixel
width
640 pixel
File history
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