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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:[]=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.




"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[]=35&mm[]=100

4:3 ratio[]=35&mm[]=100

Larger size, 3:2 ratio[]=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.[]=35&mm[]=100

added reference also as "mm[]" parameter[]=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[]=35&mm[]=100

No selected focal length[]=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[]=28&mm[]=35&mm[]=50&mm[]=85&mm[]=135

Typical pro zoom lens min and max focal lengths, compared to 50mm "normal" lens[]=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[]=14&mm[]=54&mm[]=50&mm[]=200

Huuhaakuukausi 2nd, 2009