mm.php4 instructions
This page explains how "mm.php4" should be used. "mm.php4" is tool developed by
Samuli Vahonen and it's purpose is to demonstrate graphically different focal length
relations to each another. I will not offer any support in addition to this web page
for the usage of this tool.
Usage of this tool is free. However notice that usage of this
tool is logged to database, but information in database is strictly confidental and is
only used for statistical and security purposes.
Explanation of parameters
Parameters are put after mm.php4 into the URL. Start parameters with question mark ("?")
and then add parameters in any order you prefer. Between parameters use character ambersand
("&") to separate parameters. All parameters except "sel" (selected focal length, drawn
with blue instead of black) are mandatory.
If you use this graphic in some forum or wikipedia which requires to have ".jpg" or other
string to be included into URL, for example add new "parameter" in the end of the URL:
http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100&name=mm.gif
This additional parameter can have any name what you wish as long as it's not any of the
parameters defined below.
"format" - File format
Three image formats are supported: GIF, PNG and JPEG. Parameter name is "format" and
image format is given after that in capilal letters.
GIF http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=GIF&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
PNG http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
JPEG http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=JPEG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
"x" and "y" - Image size
Image size is set at pixels. Depending of ratio of pixels the image ratio can be adjusted
to match your camera's image ratio, for example 600 by 400 pixels to match 3:2 ratio or
400 by 300 pixels to match 4:3 ratio.
3:2 ratio http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
4:3 ratio http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=200&y=150&ref=24&sel=50&mm[]=35&mm[]=100
Larger size, 3:2 ratio http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=500&y=333&ref=24&sel=50&mm[]=35&mm[]=100
"ref" - Reference
Reference focal length which needs to be shortest focal length show in picture. Reference
focal length is drawn with gray color. If you prefer to have all focal lengths drawn with
black color then give same focal length also in the "mm[]" parameter.
http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
added reference also as "mm[]" parameter http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=24&mm[]=35&mm[]=100
"sel" - Selected focal length
Selected focal length is special focal length illustrated with blue color. This parameter is
optional, if not given then all focal lengths are drawn black/gray.
50mm as "selected" focal length http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
No selected focal length http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=225&y=150&ref=24&sel=50&mm[]=35&mm[]=100
"mm[]" - List of focal lenghts
This tool can present multiple focal lengths. There is no limit how many focal limits are
drawn, however in practice in order to avoid overlap you don't want draw 100 different focal
lengths to one graph...
Classic prime focal lengths http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=500&y=333&ref=28&mm[]=28&mm[]=35&mm[]=50&mm[]=85&mm[]=135
Typical pro zoom lens min and max focal lengths, compared to 50mm "normal" lens http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=500&y=333&ref=16&sel=50&mm[]=16&mm[]=35&mm[]=24&mm[]=70&mm[]=200
Four thirds (14-54 & 50-200) example demonstrating problem if shown focal lengths are too
close to each other and 4:3 ratio
http://www.vahonen.com/photo/equipment/lenses/mm.php4?format=PNG&x=500&y=375&ref=14&mm[]=14&mm[]=54&mm[]=50&mm[]=200
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