document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=173661>Question 173661</A>: <I><SPAN STYLE=\"word-break: break-all;\"> What is the f number of a 15cm diameter, .9 focal length lens? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #128532 by </B><A HREF=/tutors/aboutme.mpl?userid=Mathtut><B>Mathtut(3670)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Mathtut><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=128532\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> f stop or focal ration would be equal to focal length divided by the diameter of the lens<BR>\n" );
document.write( ":f=fstop<BR>\n" );
document.write( " F=focal length<BR>\n" );
document.write( " D=diameter of lens<BR>\n" );
document.write( "f=F/D<BR>\n" );
document.write( ":<BR>\n" );
document.write( "<IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight%28f=.9%2F15=.06%29 ALIGN=MIDDLE  ALT=\"highlight%28f=.9%2F15=.06%29\"   DISABLED_style= \"max-width:90%; height:auto;\" > usually diameters of lens are in mm so this is a very large aperature\r<BR>\n" );
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document.write( "this of course was assuming the the focal length was in centimeters also </SPAN>\n" );
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